< draft-ietf-manet-dlep-17.txt		draft-ietf-manet-dlep-18.txt >
	Mobile Ad hoc Networks Working Group S. Ratliff		Mobile Ad hoc Networks Working Group S. Ratliff
	Internet-Draft VT iDirect		Internet-Draft VT iDirect
	Intended status: Standards Track B. Berry		Intended status: Standards Track S. Jury
	Expires: April 17, 2016		Expires: August 7, 2016 Cisco Systems
	S. Jury
	Cisco Systems
	D. Satterwhite		D. Satterwhite
	Broadcom		Broadcom
	R. Taylor		R. Taylor
	Airbus Defence & Space		Airbus Defence & Space
	October 16, 2015		B. Berry
			February 4, 2016
	Dynamic Link Exchange Protocol (DLEP)		Dynamic Link Exchange Protocol (DLEP)
	draft-ietf-manet-dlep-17		draft-ietf-manet-dlep-18
	Abstract		Abstract
	When routing devices rely on modems to effect communications over		When routing devices rely on modems to effect communications over
	wireless links, they need timely and accurate knowledge of the		wireless links, they need timely and accurate knowledge of the
	characteristics of the link (speed, state, etc.) in order to make		characteristics of the link (speed, state, etc.) in order to make
	routing decisions. In mobile or other environments where these		routing decisions. In mobile or other environments where these
	characteristics change frequently, manual configurations or the		characteristics change frequently, manual configurations or the
	inference of state through routing or transport protocols does not		inference of state through routing or transport protocols does not
	allow the router to make the best decisions. A bidirectional, event-		allow the router to make the best decisions. A bidirectional, event-
	skipping to change at page 1, line 44 ¶		skipping to change at page 1, line 43 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on April 17, 2016.		This Internet-Draft will expire on August 7, 2016.
	Copyright Notice		Copyright Notice
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	document authors. All rights reserved.		document authors. All rights reserved.
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	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
	1.1. Protocol Overview . . . . . . . . . . . . . . . . . . . . 7		1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 7
	1.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 8		2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7
	2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 8		2.1. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 9
	3. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 8		3. Destinations . . . . . . . . . . . . . . . . . . . . . . . . 9
	3.1. Mandatory Metrics . . . . . . . . . . . . . . . . . . . . 9		3.1. Router-requested Destinations . . . . . . . . . . . . . . 10
	4. DLEP Signal and Message Processing . . . . . . . . . . . . . 10		4. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
	4.1. Transaction Model . . . . . . . . . . . . . . . . . . . . 11		5. DLEP Session Flow . . . . . . . . . . . . . . . . . . . . . . 12
	5. DLEP Session Flow . . . . . . . . . . . . . . . . . . . . . . 11
	5.1. Peer Discovery State . . . . . . . . . . . . . . . . . . 12		5.1. Peer Discovery State . . . . . . . . . . . . . . . . . . 12
	5.2. Session Initialization State . . . . . . . . . . . . . . 13		5.2. Session Initialization State . . . . . . . . . . . . . . 14
	5.3. In-Session State . . . . . . . . . . . . . . . . . . . . 14		5.3. In-Session State . . . . . . . . . . . . . . . . . . . . 15
	5.3.1. Heartbeats . . . . . . . . . . . . . . . . . . . . . 15		5.3.1. Heartbeats . . . . . . . . . . . . . . . . . . . . . 16
	5.4. Session Termination State . . . . . . . . . . . . . . . . 15		5.4. Session Termination State . . . . . . . . . . . . . . . . 16
	6. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . 16		5.5. Session Reset state . . . . . . . . . . . . . . . . . . . 17
	6.1. Experiments . . . . . . . . . . . . . . . . . . . . . . . 17		5.5.1. Unexpected TCP connection termination . . . . . . . . 17
	7. Scalability . . . . . . . . . . . . . . . . . . . . . . . . . 17		6. Transaction Model . . . . . . . . . . . . . . . . . . . . . . 17
	8. DLEP Signal and Message Structure . . . . . . . . . . . . . . 17		7. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . 18
	8.1. DLEP Signal Header . . . . . . . . . . . . . . . . . . . 18		7.1. Experiments . . . . . . . . . . . . . . . . . . . . . . . 18
	8.2. DLEP Message Header . . . . . . . . . . . . . . . . . . . 19		8. Scalability . . . . . . . . . . . . . . . . . . . . . . . . . 19
	8.3. DLEP Generic Data Item . . . . . . . . . . . . . . . . . 19		9. DLEP Signal and Message Structure . . . . . . . . . . . . . . 19
	9. DLEP Signals and Messages . . . . . . . . . . . . . . . . . . 20		9.1. DLEP Signal Header . . . . . . . . . . . . . . . . . . . 20
	9.1. Peer Discovery Signal . . . . . . . . . . . . . . . . . . 21		9.2. DLEP Message Header . . . . . . . . . . . . . . . . . . . 20
	9.2. Peer Offer Signal . . . . . . . . . . . . . . . . . . . . 22		9.3. DLEP Generic Data Item . . . . . . . . . . . . . . . . . 21
	9.3. Session Initialization Message . . . . . . . . . . . . . 22		10. DLEP Signals and Messages . . . . . . . . . . . . . . . . . . 21
	9.4. Session Initialization Response Message . . . . . . . . . 23		10.1. Peer Discovery Signal . . . . . . . . . . . . . . . . . 22
	9.5. Session Update Message . . . . . . . . . . . . . . . . . 25		10.2. Peer Offer Signal . . . . . . . . . . . . . . . . . . . 23
	9.6. Session Update Response Message . . . . . . . . . . . . . 26		10.3. Session Initialization Message . . . . . . . . . . . . . 23
	9.7. Session Termination Message . . . . . . . . . . . . . . . 26		10.4. Session Initialization Response Message . . . . . . . . 24
	9.8. Session Termination Response Message . . . . . . . . . . 27		10.5. Session Update Message . . . . . . . . . . . . . . . . . 26
	9.9. Destination Up Message . . . . . . . . . . . . . . . . . 27		10.6. Session Update Response Message . . . . . . . . . . . . 27
	9.10. Destination Up Response Message . . . . . . . . . . . . . 28		10.7. Session Termination Message . . . . . . . . . . . . . . 28
	9.11. Destination Down Message . . . . . . . . . . . . . . . . 29		10.8. Session Termination Response Message . . . . . . . . . . 28
	9.12. Destination Down Response Message . . . . . . . . . . . . 29		10.9. Destination Up Message . . . . . . . . . . . . . . . . . 28
	9.13. Destination Update Message . . . . . . . . . . . . . . . 30		10.10. Destination Up Response Message . . . . . . . . . . . . 30
	9.14. Heartbeat Message . . . . . . . . . . . . . . . . . . . . 31		10.11. Destination Announce Message . . . . . . . . . . . . . . 30
	9.15. Link Characteristics Request Message . . . . . . . . . . 31		10.12. Destination Announce Response Message . . . . . . . . . 31
	9.16. Link Characteristics Response Message . . . . . . . . . . 32		10.13. Destination Down Message . . . . . . . . . . . . . . . . 32
	10. DLEP Data Items . . . . . . . . . . . . . . . . . . . . . . . 33		10.14. Destination Down Response Message . . . . . . . . . . . 32
	10.1. Status . . . . . . . . . . . . . . . . . . . . . . . . . 34		10.15. Destination Update Message . . . . . . . . . . . . . . . 33
	10.2. IPv4 Connection Point . . . . . . . . . . . . . . . . . 37		10.16. Heartbeat Message . . . . . . . . . . . . . . . . . . . 34
	10.3. IPv6 Connection Point . . . . . . . . . . . . . . . . . 38		10.17. Link Characteristics Request Message . . . . . . . . . . 35
	10.4. Peer Type . . . . . . . . . . . . . . . . . . . . . . . 39		10.18. Link Characteristics Response Message . . . . . . . . . 35
	10.5. Heartbeat Interval . . . . . . . . . . . . . . . . . . . 40		11. DLEP Data Items . . . . . . . . . . . . . . . . . . . . . . . 37
	10.6. Extensions Supported . . . . . . . . . . . . . . . . . . 40		11.1. Status . . . . . . . . . . . . . . . . . . . . . . . . . 38
	10.7. MAC Address . . . . . . . . . . . . . . . . . . . . . . 41		11.2. IPv4 Connection Point . . . . . . . . . . . . . . . . . 40
	10.8. IPv4 Address . . . . . . . . . . . . . . . . . . . . . . 42		11.3. IPv6 Connection Point . . . . . . . . . . . . . . . . . 41
	10.9. IPv6 Address . . . . . . . . . . . . . . . . . . . . . . 43		11.4. Peer Type . . . . . . . . . . . . . . . . . . . . . . . 42
	10.10. IPv4 Attached Subnet . . . . . . . . . . . . . . . . . . 44		11.5. Heartbeat Interval . . . . . . . . . . . . . . . . . . . 43
	10.11. IPv6 Attached Subnet . . . . . . . . . . . . . . . . . . 45		11.6. Extensions Supported . . . . . . . . . . . . . . . . . . 43
	10.12. Maximum Data Rate (Receive) . . . . . . . . . . . . . . 46		11.7. MAC Address . . . . . . . . . . . . . . . . . . . . . . 44
	10.13. Maximum Data Rate (Transmit) . . . . . . . . . . . . . . 46		11.8. IPv4 Address . . . . . . . . . . . . . . . . . . . . . . 45
	10.14. Current Data Rate (Receive) . . . . . . . . . . . . . . 47		11.9. IPv6 Address . . . . . . . . . . . . . . . . . . . . . . 46
	10.15. Current Data Rate (Transmit) . . . . . . . . . . . . . . 48		11.10. IPv4 Attached Subnet . . . . . . . . . . . . . . . . . . 47
	10.16. Latency . . . . . . . . . . . . . . . . . . . . . . . . 49		11.11. IPv6 Attached Subnet . . . . . . . . . . . . . . . . . . 48
	10.17. Resources (Receive) . . . . . . . . . . . . . . . . . . 50		11.12. Maximum Data Rate (Receive) . . . . . . . . . . . . . . 49
	10.18. Resources (Transmit) . . . . . . . . . . . . . . . . . . 50		11.13. Maximum Data Rate (Transmit) . . . . . . . . . . . . . . 49
	10.19. Relative Link Quality (Receive) . . . . . . . . . . . . 51		11.14. Current Data Rate (Receive) . . . . . . . . . . . . . . 50
	10.20. Relative Link Quality (Transmit) . . . . . . . . . . . . 52		11.15. Current Data Rate (Transmit) . . . . . . . . . . . . . . 51
	11. Security Considerations . . . . . . . . . . . . . . . . . . . 52		11.16. Latency . . . . . . . . . . . . . . . . . . . . . . . . 52
	12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 53		11.17. Resources (Receive) . . . . . . . . . . . . . . . . . . 52
	12.1. Registrations . . . . . . . . . . . . . . . . . . . . . 53		11.18. Resources (Transmit) . . . . . . . . . . . . . . . . . . 53
	12.2. Expert Review: Evaluation Guidelines . . . . . . . . . . 54		11.19. Relative Link Quality (Receive) . . . . . . . . . . . . 54
	12.3. Signal/Message Type Registration . . . . . . . . . . . . 54		11.20. Relative Link Quality (Transmit) . . . . . . . . . . . . 54
	12.4. DLEP Data Item Registrations . . . . . . . . . . . . . . 54		11.21. Maximum Transmission Unit (MTU) . . . . . . . . . . . . 55
	12.5. DLEP Status Code Registrations . . . . . . . . . . . . . 54		12. Security Considerations . . . . . . . . . . . . . . . . . . . 56
	12.6. DLEP Extensions Registrations . . . . . . . . . . . . . 54		13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 56
	12.7. DLEP Well-known Port . . . . . . . . . . . . . . . . . . 55		13.1. Registrations . . . . . . . . . . . . . . . . . . . . . 56
	12.8. DLEP IPv6 Link-local Multicast Address . . . . . . . . . 55		13.2. Signal/Message Type Registration . . . . . . . . . . . . 57
	13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 55		13.3. DLEP Data Item Registrations . . . . . . . . . . . . . . 57
	14. References . . . . . . . . . . . . . . . . . . . . . . . . . 55		13.4. DLEP Status Code Registrations . . . . . . . . . . . . . 57
	14.1. Normative References . . . . . . . . . . . . . . . . . . 55		13.5. DLEP Extensions Registrations . . . . . . . . . . . . . 58
	14.2. Informative References . . . . . . . . . . . . . . . . . 55		13.6. DLEP Well-known Port . . . . . . . . . . . . . . . . . . 58
	Appendix A. Discovery Signal Flows . . . . . . . . . . . . . . . 56		13.7. DLEP IPv4 Link-local Multicast Address . . . . . . . . . 58
	Appendix B. Peer Level Message Flows . . . . . . . . . . . . . . 56		13.8. DLEP IPv6 Link-local Multicast Address . . . . . . . . . 58
	B.1. Session Initialization . . . . . . . . . . . . . . . . . 56		14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 58
	B.2. Session Initialization - Refused . . . . . . . . . . . . 57		15. References . . . . . . . . . . . . . . . . . . . . . . . . . 59
	B.3. Router Changes IP Addresses . . . . . . . . . . . . . . . 57		15.1. Normative References . . . . . . . . . . . . . . . . . . 59
	B.4. Modem Changes Session-wide Metrics . . . . . . . . . . . 57		15.2. Informative References . . . . . . . . . . . . . . . . . 59
	B.5. Router Terminates Session . . . . . . . . . . . . . . . . 58		Appendix A. Discovery Signal Flows . . . . . . . . . . . . . . . 59
	B.6. Modem Terminates Session . . . . . . . . . . . . . . . . 58		Appendix B. Peer Level Message Flows . . . . . . . . . . . . . . 60
	B.7. Session Heartbeats . . . . . . . . . . . . . . . . . . . 59		B.1. Session Initialization . . . . . . . . . . . . . . . . . 60
	B.8. Router Detects a Heartbeat timeout . . . . . . . . . . . 60		B.2. Session Initialization - Refused . . . . . . . . . . . . 61
	B.9. Modem Detects a Heartbeat timeout . . . . . . . . . . . . 61		B.3. Router Changes IP Addresses . . . . . . . . . . . . . . . 61
	Appendix C. Destination Specific Signal Flows . . . . . . . . . 61		B.4. Modem Changes Session-wide Metrics . . . . . . . . . . . 61
	C.1. Common Destination Signaling . . . . . . . . . . . . . . 61		B.5. Router Terminates Session . . . . . . . . . . . . . . . . 62
	C.2. Multicast Destination Signaling . . . . . . . . . . . . . 62		B.6. Modem Terminates Session . . . . . . . . . . . . . . . . 62
	C.3. Link Characteristics Request . . . . . . . . . . . . . . 62		B.7. Session Heartbeats . . . . . . . . . . . . . . . . . . . 63
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 63		B.8. Router Detects a Heartbeat timeout . . . . . . . . . . . 64
			B.9. Modem Detects a Heartbeat timeout . . . . . . . . . . . . 65
			Appendix C. Destination Specific Message Flows . . . . . . . . . 65
			C.1. Common Destination Notification . . . . . . . . . . . . . 65
			C.2. Multicast Destination Notification . . . . . . . . . . . 66
			C.3. Link Characteristics Request . . . . . . . . . . . . . . 67
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 68
	1. Introduction		1. Introduction
	There exist today a collection of modem devices that control links of		There exist today a collection of modem devices that control links of
	variable datarate and quality. Examples of these types of links		variable datarate and quality. Examples of these types of links
	include line-of-sight (LOS) terrestrial radios, satellite terminals,		include line-of-sight (LOS) terrestrial radios, satellite terminals,
	and broadband modems. Fluctuations in speed and quality of these		and broadband modems. Fluctuations in speed and quality of these
	links can occur due to configuration, or on a moment-to-moment basis,		links can occur due to configuration, or on a moment-to-moment basis,
	due to physical phenomena like multipath interference, obstructions,		due to physical phenomena like multipath interference, obstructions,
	rain fade, etc. It is also quite possible that link quality and		rain fade, etc. It is also quite possible that link quality and
	skipping to change at page 4, line 48 ¶		skipping to change at page 5, line 5 ¶
	In addition to utilizing variable datarate links, mobile networks are		In addition to utilizing variable datarate links, mobile networks are
	challenged by the notion that link connectivity will come and go over		challenged by the notion that link connectivity will come and go over
	time, without an effect on a router's interface state (Up or Down).		time, without an effect on a router's interface state (Up or Down).
	Effectively utilizing a relatively short-lived connection is		Effectively utilizing a relatively short-lived connection is
	problematic in IP routed networks, as routing protocols tend to rely		problematic in IP routed networks, as routing protocols tend to rely
	on interface state and independent timers at OSI Layer 3 to maintain		on interface state and independent timers at OSI Layer 3 to maintain
	network convergence (e.g., HELLO messages and/or recognition of DEAD		network convergence (e.g., HELLO messages and/or recognition of DEAD
	routing adjacencies). These dynamic connections can be better		routing adjacencies). These dynamic connections can be better
	utilized with an event-driven paradigm, where acquisition of a new		utilized with an event-driven paradigm, where acquisition of a new
	neighbor (or loss of an existing one) is signaled, as opposed to a		neighbor (or loss of an existing one) is signaled, as opposed to a
	paradigm driven by timers and/or interface state.		paradigm driven by timers and/or interface state. DLEP not only
			implements such an event-driven paradigm, but does so over a local (1
			hop) TCP session, which guarantees delivery of the event messages.
	Another complicating factor for mobile networks are the different		Another complicating factor for mobile networks are the different
	methods of physically connecting the modem devices to the router.		methods of physically connecting the modem devices to the router.
	Modems can be deployed as an interface card in a router's chassis, or		Modems can be deployed as an interface card in a router's chassis, or
	as a standalone device connected to the router via Ethernet or serial		as a standalone device connected to the router via Ethernet or serial
	link. In the case of Ethernet attachment, with existing protocols		link. In the case of Ethernet attachment, with existing protocols
	and techniques, routing software cannot be aware of convergence		and techniques, routing software cannot be aware of convergence
	events occurring on the radio link (e.g., acquisition or loss of a		events occurring on the radio link (e.g., acquisition or loss of a
	potential routing neighbor), nor can the router be aware of the		potential routing neighbor), nor can the router be aware of the
	actual capacity of the link. This lack of awareness, along with the		actual capacity of the link. This lack of awareness, along with the
	variability in datarate, leads to a situation where finding the		variability in datarate, leads to a situation where finding the
	(current) best route through the network to a given destination is		(current) best route through the network to a given destination is
	difficult to establish and properly maintain. This is especially		difficult to establish and properly maintain. This is especially
	skipping to change at page 6, line 23 ¶		skipping to change at page 7, line 6 ¶
	Figure 2 shows how DLEP can support a configuration where routers are		Figure 2 shows how DLEP can support a configuration where routers are
	connected with different link types. In this example, Modem A		connected with different link types. In this example, Modem A
	implements a point-to-point link, and Modem B is connected via a		implements a point-to-point link, and Modem B is connected via a
	shared medium. In both cases, the DLEP protocol is used to report		shared medium. In both cases, the DLEP protocol is used to report
	the characteristics of the link (datarate, latency, etc.) to routers.		the characteristics of the link (datarate, latency, etc.) to routers.
	The modem is also able to use the DLEP session to notify the router		The modem is also able to use the DLEP session to notify the router
	when the remote node is lost, shortening the time required to re-		when the remote node is lost, shortening the time required to re-
	converge the network.		converge the network.
	+--------+ +--------+		+--------+ +--------+
	+----+ Modem A| | Modem A+---+		+----+ Modem | | Modem +---+
	| | Device | <===== // ======> | Device | |		| | Device | | Device |
			| | Type A | <===== // ======> | Type A | |
	| +--------+ P-2-P Link +--------+ |		| +--------+ P-2-P Link +--------+ |
	+---+----+ +---+----+		+---+----+ +---+----+
	| Router | | Router |		| Router | | Router |
	| | | |		| | | |
	+---+----+ +---+----+		+---+----+ +---+----+
	| +--------+ +--------+ |		| +--------+ +--------+ |
	+-----+ Modem B| | Modem B| |		+-----+ Modem | | Modem | |
	| Device | o o o o o o o o | Device +--+		| Device | o o o o o o o o | Device +--+
	+--------+ o Shared o +--------+		| Type B | o Shared o | Type B |
	o Medium o		+--------+ o Medium o +--------+
	o o		o o
	o o		o o
	o o		o o
	o		o
	+--------+		+--------+
	| Modem B|		| Modem |
	| Device |		| Device |
			| Type B |
	+---+----+		+---+----+
	|		|
	|		|
	+---+----+		+---+----+
	| Router |		| Router |
	| |		| |
	+--------+		+--------+
	Figure 2: DLEP Network with Multiple Modem Devices		Figure 2: DLEP Network with Multiple Modem Devices
	1.1. Protocol Overview		1.1. Requirements
	As mentioned earlier, DLEP defines a set of messages used by modems		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	and their attached routers. The messages are used to communicate		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	events that occur on the physical link(s) managed by the modem: for		"OPTIONAL" in this document are to be interpreted as described in BCP
	example, a remote node entering or leaving the network, or that the		14, RFC 2119 [RFC2119].
	link has changed. Associated with these messages are a set of data
	items - information that describes the remote node (e.g., address		2. Protocol Overview
	information), and/or the characteristics of the link to the remote
	node.		DLEP defines a set of messages used by modems and their attached
			routers to communicate events that occur on the physical link(s)
			managed by the modem: for example, a remote node entering or leaving
			the network, or that the link has changed. Associated with these
			messages are a set of Data Items - information that describes the
			remote node (e.g., address information), and/or the characteristics
			of the link to the remote node. Throughout this document, we refer
			to a modems/routers participating in a DLEP session as 'DLEP Peers',
			unless a specific distinction (e.g. modem or router) is required.
	DLEP uses a session-oriented paradigm between the modem device and		DLEP uses a session-oriented paradigm between the modem device and
	its associated router. If multiple modem devices are attached to a		its associated router. If multiple modem devices are attached to a
	router (as in Figure 2), or the modem supports multiple connections		router (as in Figure 2), or the modem supports multiple connections
	(via multiple logical or physical interfaces), then separate DLEP		(via multiple logical or physical interfaces), then separate DLEP
	sessions exist for each modem or connection. A router and modem form		sessions exist for each modem or connection. A router and modem form
	a session by completing the discovery and initialization process.		a session by completing the discovery and initialization process.
	This router-modem session persists unless or until it either (1)		This router-modem session persists unless or until it either (1)
	times out, based on a heartbeat, or (2) is explicitly torn down by		times out, based on the absence of traffic (including heartbeats), or
	one of the participants.		(2) is explicitly torn down by one of the participants.
	The router/modem session provides a carrier for information exchange		The router/modem session provides a carrier for information exchange
	concerning 'destinations' that are available via the modem device.		concerning 'destinations' that are available via the modem device.
	Destinations can be identified by either the router or the modem, and		Destinations can be identified by either the router or the modem, and
	represent a specific, addressable location (e.g., an address) that		represent a specific, addressable location that can be reached via
	can be reached via the link(s) managed by the modem. A destination		the link(s) managed by the modem. A destination can be either
	can be either physical or logical.		physical or logical.
	The example of a physical destination would be that of a remote, far-		The example of a physical destination would be that of a remote, far-
	end router attached via the variable-quality network. As for a		end router attached via the variable-quality network.
	logical destination, the best example is that of Multicast.
	Multicast traffic destined for the variable-quality network (the		The example of a logical destination is Multicast. Multicast traffic
	network accessed via the DLEP modem) is handled in IP networks by		destined for the variable-quality network (the network accessed via
	deriving a Layer 2 MAC address based on the Layer 3 address.		the modem) is handled in IP networks by deriving a Layer 2 MAC
	Leveraging on this scheme, multicast traffic is supported in DLEP		address based on the Layer 3 address. Leveraging on this scheme,
	simply by treating the derived MAC address as any other destination		multicast traffic is supported in DLEP simply by treating the derived
	(albeit a logical one) in the network. To support these logical		MAC address as any other destination in the network. To support
	destinations, one of the DLEP participants (typically, the router)		these logical destinations, one of the DLEP participants (typically,
	informs the other as to the existence of the logical destination.		the router) informs the other as to the existence of the logical
	The modem, once it is aware of the existence of this logical		destination. The modem, once it is aware of the existence of this
	destination, reports link characteristics just as it would for any		logical destination, reports link characteristics just as it would
	other destination in the network. The specific algorithms a modem		for any other destination in the network. The specific algorithms a
	would use to derive metrics on multicast (or logical) destinations		modem would use to derive metrics on logical destinations are outside
	are outside the scope of this specification, and is left to specific		the scope of this specification, and is left to specific
	implementations to decide.		implementations to decide.
	The DLEP messages concerning destinations thus become the way for		The DLEP messages concerning destinations thus become the way for
	routers and modems to maintain, and notify each other about, an		routers and modems to maintain, and notify each other about, an
	information base representing the physical and logical (e.g.,		information base representing the physical and logical destinations
	multicast) destinations accessible via the modem device, as well as		accessible via the modem device, as well as the link characteristics
	the link characteristics to those destinations.		to those destinations.
	1.2. Requirements
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		While this document represents the best efforts of the working group
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		to be functionally complete, it is recognized that extensions to DLEP
	"OPTIONAL" in this document are to be interpreted as described in BCP		will in all likelihood be necessary as more link types are used.
	14, RFC 2119 [RFC2119].		Such extensions are defined as additional rules of behavior,
			messages, data items and/or status codes that are not defined in this
			document. DLEP contains a standard mechanism for router and modem
			implementations to negotiate the available extensions to use on a
			per-session basis.
	2. Assumptions		2.1. Assumptions
	DLEP specifies UDP multicast for single-hop discovery signalling, and		DLEP specifies UDP multicast for single-hop discovery signaling, and
	TCP for transport of the control messages. Therefore, DLEP assumes		TCP for transport of the control messages. Therefore, DLEP assumes
	that the modem and router have topologically consistent IP addresses		that the modem and router have topologically consistent IP addresses
	assigned. It is RECOMMENDED that DLEP implementations utilize IPv6		assigned. It is RECOMMENDED that DLEP implementations utilize IPv6
	link-local addresses to reduce the administrative burden of address		link-local addresses to reduce the administrative burden of address
	assignment. Other reliable transports for the protocol are possible,		assignment. DLEP relies on the guaranteed- delivery of its messages
	but are outside the scope of this document.		between router and modem, once the 1 hop discovery process is
			complete, hence, the specification of TCP to carry the messages.
			Other reliable transports for the protocol are possible, but are
			outside the scope of this document.
	DLEP assumes that the MAC address for delivering data traffic is the		DLEP assumes that the MAC address for delivering data traffic is the
	MAC address used by DLEP to identify the destination. No		MAC address used by DLEP to identify the destination. No
	manipulation or substitution is performed; the MAC address supplied		manipulation or substitution is performed; the MAC address supplied
	in a Destination Up message (Section 9.9) message is used as the OSI		in all destination messages is used as the OSI Layer 2 Destination
	Layer 2 Destination MAC address. DLEP also assumes that MAC		MAC address. DLEP also assumes that MAC addresses are unique within
	addresses are unique within the context of a router-modem session.		the context of a router-modem session.
	DLEP assumes that security on the session (e.g., authentication of		The reliance on MAC addresses by DLEP forces the assumption that
	session partners, encryption of traffic, or both) is dealt with by		participating DLEP peers are on a single segment (either physical or
	the underlying transport mechanism (e.g., by using a transport such		logically, via tunneling protocols) at Layer 2. DLEP further assumes
	as TLS [RFC5246]).		that security of the implementations (e.g., authentication of
			stations, encryption of traffic, or both) is dealt with by by
			utilizing Layer 2 security techniques. This reliance on Layer 2
			mechanisms secures all DLEP messages - both the UDP discovery
			messages and the TCP control messages.
	3. Metrics		3. Destinations
			Destination messages describe the acquisition and loss of network
			destinations, and control the flow of information about the
			destinations in the several ways. A destination MUST contain a MAC
			address; it MAY optionally include a Layer 3 address (or multiple
			addresses). The MAC address MAY reference a logical destination, as
			in a derived multicast MAC address, as well as a physical device. As
			destinations are discovered, DLEP routers and modems build an
			information base of destinations accessible via the modem.
			DLEP can support MAC addresses in either EUI-48 or EUI-64 format,
			with the restriction that all MAC addresses for a given DLEP session
			MUST be in the same format, and MUST be consistent with the MAC
			address format of the connected modem (e.g., if the modem is
			connected to the router with an EUI-48 MAC, all destination addresses
			via that modem MUST be expressed in EUI-48 format).
			Destination messages trigger creation/maintenance/deletion of
			destinations in the information base of the recipient. For example,
			a modem will inform its attached router of the presence of a new
			destination via the Destination Up message (Section 10.9). Receipt
			of a Destination Up causes the router to allocate the necessary
			resources, creating an entry in the information base with the
			specifics (i.e. MAC Address, Latency, Data Rate, etc.) of the
			destination. The loss of a destination is communicated via the
			Destination Down message (Section 10.13), and changes in status to
			the destination (e.g., varying link quality, or addressing changes)
			are communicated via the Destination Update message (Section 10.15).
			The information on a given destination will persist in the
			implementation's information base until a Destination Down message is
			received, indicating that the peer has lost contact or interest with
			the remote node, or the implementation transitions to the Session
			Termination state.
			3.1. Router-requested Destinations
			Usually a modem will discover the presence of one or more remote
			router/modem pairs and announce each destination's arrival by sending
			a corresponding Destination Up message to its peer. However, there
			may be times when a router wishes to express an interest in the
			status of the link to a logical destination that has yet to be
			announced, typically a multicast destination. To facilitate this,
			DLEP provides the Destination Announce (Section 10.11) and
			Destination Announce Response (Section 10.12) messages. These
			messages have similar semantics to the Destination Up and Destination
			Up Response messages, but flow from router to modem.
			After successfully receiving and processing a Destination Announce
			message, a modem then announces changes to the link to the logical
			destination via Destination Update messages. A modem MAY refuse a
			Destination Announce message by replying with a Destination Announce
			Response message with a 'Request Denied' status code, see Table 3.
			A Destination Announce message MAY also be used by a router to
			request information concerning a destination that it has previously
			declined interest in, via the 'Not Interested' status code, see
			Table 3, or declared as down, via the Destination Down message.
			One of the advantages of implementing DLEP is to leverage the modem's
			knowledge of the links between remote destinations allowing routers
			to avoid using probed neighbor discovery techniques, therefore modem
			implementations SHOULD announce available destinations via the
			Destination Up message, rather than relying on Destination Announce
			messages.
			4. Metrics
	DLEP includes the ability for the router and modem to communicate		DLEP includes the ability for the router and modem to communicate
	metrics that reflect the characteristics (e.g., datarate, latency) of		metrics that reflect the characteristics (e.g., datarate, latency) of
	the variable-quality link in use. DLEP does not specify how a given		the variable-quality link in use. DLEP does not specify how a given
	metric value is to be calculated, rather, the protocol assumes that		metric value is to be calculated, rather, the protocol assumes that
	metrics have been calculated with a 'best effort', incorporating all		metrics have been calculated by a 'best effort', incorporating all
	pertinent data that is available to the modem device.		pertinent data that is available to the modem device.
	DLEP allows for metrics to be sent within two contexts - metrics for		DLEP allows for metrics to be sent within two contexts - metrics for
	a specific destination within the network (e.g., a specific router),		a specific destination within the network (e.g., a specific router),
	and per-session (those that apply to all destinations accessed via		and per-session (those that apply to all destinations accessed via
	the modem). Most metrics can be further subdivided into transmit and		the modem). Most metrics can be further subdivided into transmit and
	receive metrics. In cases where metrics are provided at session		receive metrics. In cases where metrics are provided at session
	level, the receiver MUST propagate the metrics to all entries in its		level, the router MUST propagate the metrics to all entries in its
	information base for destinations that are accessed via the		information base for destinations that are accessed via the modem.
	originator.
	It is left to implementations to choose sensible default values based
	on their specific characteristics. Modems having static (non-
	changing) link metric characteristics MAY report metrics only once
	for a given destination (or once on a modem-wide basis, if all
	connections via the modem are of this static nature).
	DLEP modem implementations MUST announce all metric items that will		DLEP modem implementations MUST announce all metric items that will
	be reported during the session, and provide default values for those		be reported during the session, and provide default values for those
	metrics, in the Session Initialization Response message		metrics, in the Session Initialization Response message
	(Section 9.4). In order to use a metric type that was not included		(Section 10.4). In order to use a metric type that was not included
	in the Session Initialization Response message, modem implementations		in the Session Initialization Response message, modem implementations
	MUST terminate the session with the router (via the Session Terminate		MUST terminate the session with the router (via the Session Terminate
	message (Section 9.7)), and establish a new session.		message (Section 10.7)), and establish a new session. A modem MUST
			include the following list of metrics in the Session Initialization
	A DLEP participant MAY send metrics both in a session context (via		Response message:
	the Session Update message) and a specific destination context (via
	Destination Update) at any time. The most recently received metric
	value MUST take precedence over any earlier value, regardless of
	context - that is: 1. If the receiver gets metrics in a specific
	destination context (via Destination Update), then the specific
	destination is updated with the new metric. 2. If the receiver gets
	metrics in a modem-wide context (via Peer Update), then the received
	metrics for all destinations accessed via the modem MUST be updated
	to the newly received value.
	3.1. Mandatory Metrics
	As mentioned above, DLEP modem implementations MUST announce all
	supported metric items during the Session Initialization state.
	However, a modem MUST include the following list of metrics in the
	Session Initialization Response message (Section 9.4):
	o Maximum Data Rate (Receive) (Section 10.12)
	o Maximum Data Rate (Transmit) (Section 10.13)
	o Current Data Rate (Receive) (Section 10.14)
	o Current Data Rate (Transmit) (Section 10.15)
	o Latency (Section 10.16)
	4. DLEP Signal and Message Processing
	Most messages in DLEP are members of a request/response pair, e.g.
	Destination Up message (Section 9.9), and Destination Up Response
	message (Section 9.10). As mentioned before, session message pairs
	control the flow of the session through the various states, e.g. an
	implementation MUST NOT leave the Session Initialization state until
	a Session Initialization message (Section 9.3) and Session
	Initialization Response message (Section 9.4) have been exchanged.
	Destination message pairs describe the arrival and departure of		o Maximum Data Rate (Receive) (Section 11.12)
	logical destinations, and control the flow of information about the
	destinations in the several ways. A destination MUST contain a MAC
	address, it MAY optionally include a Layer 3 address (or addresses).
	The MAC address MAY reference a logical destination, as in a derived
	multicast MAC address, as well as a physical device. As destinations
	are discovered, DLEP routers and modems build an information base of
	destinations accessible via the modem.
	DLEP can support MAC addresses in either EUI-48 or EUI-64 format,		o Maximum Data Rate (Transmit) (Section 11.13)
	with the restriction that all MAC addresses for a given DLEP session
	MUST be in the same format, and MUST be consistent with the MAC
	address format of the connected modem (e.g., if the modem is
	connected to the router with an EUI-48 MAC, all destination addresses
	via that modem MUST be expressed in EUI-48 format).
	Prior to the exchange of a pair of Destination Up and Destination Up		o Current Data Rate (Receive) (Section 11.14)
	Response messages, no messages concerning the logical destination
	identified by the MAC Address data item (Section 10.7) may be sent.
	An implementation receiving a message with such an unannounced
	destination MUST terminate the session by issuing a Session
	Termination message (Section 9.7) with a status code of 'Invalid
	Destination', see Table 3, and transition to the Session Termination
	state.
	The receiver of a Destination Up message MAY decline further messages		o Current Data Rate (Transmit) (Section 11.15)
	concerning a given destination by sending a Destination Up Response
	with a status code of 'Not Interested', see Table 3. Receivers of
	such responses MUST NOT send further messages concerning that
	destination to the peer.
	After exchanging a pair of Destination Down (Section 9.11) and		o Latency (Section 11.16)
	Destination Down Response (Section 9.12) messages, no messages
	concerning the logical destination identified by the MAC Address data
	item may be a sent without a previously sending a new Destination Up
	message. An implementation receiving a message about a destination
	previously announced as 'down' MUST terminate the session by issuing
	a Session Termination message with a status code of 'Invalid
	Destination' and transition to the Session Termination state.
	4.1. Transaction Model		A DLEP modem MAY send metrics both in a session context (via the
			Session Update message) and a specific destination context (via
			Destination Update) at any time. The most recently received metric
			value MUST take precedence over any earlier value, regardless of
			context - that is:
	DLEP defines a simple message transaction model: Only one (1) request		1. If the router receives metrics in a specific destination context
	per destination may be in progress at a time. A message transaction		(via the Destination Update message), then the specific
	is considered complete when a response matching a previously issued		destination is updated with the new metric.
	request is received. If a peer receives a request for a destination
	for which there is already an outstanding request, the peer MUST
	terminate the session by issuing a Session Termination message
	(Section 9.7) with a status code of 'Unexpected Message', see
	Table 3, and transition to the Session Termination state. There is
	no restriction to the total number of message transactions in
	progress at a time, as long as each transaction refers to a different
	destination.
	It should be noted that some requests may take a considerable amount		2. If the router receives metrics in a modem-wide context (via the
	of time for some peers to complete, for example a modem handling a		Session Update message), then the metrics for all destinations
	multicast destination up request may have to perform a complex		accessed via the modem MUST be updated with the new metric.
	network reconfiguration. A sending implementation MUST be able to
	handle such long running transactions gracefully.
	Additionally, only one (1) session request, e.g. a Session		It is left to implementations to choose sensible default values based
	Initialization message (Section 9.3) may be in progress at a time.		on their specific characteristics. Modems having static (non-
	As above, a session transaction is considered complete when a		changing) link metric characteristics MAY report metrics only once
	response matching a previously issued request is received. If a peer		for a given destination (or once on a modem-wide basis, if all
	receives a session request while there is already a session request		connections via the modem are of this static nature).
	in progress, the peer MUST terminate the session by issuing a Session
	Termination message with a status code of 'Unexpected Message', and
	transition to the Session Termination state. Only the Session
	Termination message may be issued when a session transaction is in
	progress. Heartbeat messages (Section 9.14) MUST NOT be considered
	part of a session transaction.
	DLEP transactions do not time out and are not cancellable. An		In addition to communicating existing metrics about the link, DLEP
	implementation can detect if a peer has failed in some way by use of		provides a message allowing a router to request a different datarate
	the session heartbeat mechanism during the In-Session state, see		or latency from the modem. This message is the Link Characteristics
	Section 5.3.		Request message (Section 10.17), and gives the router the ability to
			deal with requisite increases (or decreases) of allocated datarate/
			latency in demand-based schemes in a more deterministic manner.
	5. DLEP Session Flow		5. DLEP Session Flow
	All DLEP peers transition through four (4) distinct states during the		All Peers participating in a DLEP session transition through five (5)
	lifetime of a DLEP session:		distinct states during the lifetime of a DLEP session:
	o Peer Discovery		o Peer Discovery
	o Session Initialization		o Session Initialization
	o In-Session		o In-Session
	o Session Termination		o Session Termination
			o Session Reset
	The Peer Discovery state is OPTIONAL to implement for routers. If it		The Peer Discovery state is OPTIONAL to implement for routers. If it
	is used, this state is the initial state. If it is not used, then		is used, this state is the initial state. If it is not used, then a
	one or more preconfigured address/port combinations SHOULD be		preconfigured TCP address/port combination MUST be provided to the
	provided to the router, and the device starts in the Session		router, and the router starts in the Session Initialization state.
	Initialization state.
	Modems MUST support the Peer Discovery state.		Modems MUST support the Peer Discovery state.
	5.1. Peer Discovery State		5.1. Peer Discovery State
	In the Peer Discovery state, routers MUST send UDP packets containing		In the Peer Discovery state, if the router implementation supports
	a Peer Discovery signal (Section 9.1) to the DLEP well-known IPv6		IPv6, it SHOULD send UDP packets containing a Peer Discovery signal
	link-local multicast address (Section 12.8) and port number		(Section 10.1) to the DLEP well-known IPv6 link-local multicast
	(Section 12.7), setting the packet source address to a valid local		address (Section 13.8) and port number (Section 13.6), setting the
	IPv6 address and the source port to an unused port in the range 49152		packet source address to a valid IPv6 link-local address and the
	to 65535. If the router implementation supports IPv4, then they MAY		source port to a valid port number.
	also broadcast Peer Discovery signals in UDP packets to the IPv4
	broadcast address (255.255.255.255), setting the packet source		If the router implementation supports IPv4, it SHOULD send UDP
	address to a valid local IPv4 address and the source port to an		packets containing a Peer Discovery signal (Section 10.1) to the DLEP
	unused port in the range 49152 to 65535.		well-known IPv4 link-local multicast address (Section 13.7) and port
			number (Section 13.6), setting the packet source address to a valid
			local IPv4 address and the source port to a valid port number.
	The implementation then waits for a unicast UDP packet containing a		The implementation then waits for a unicast UDP packet containing a
	Peer Offer signal (Section 9.2) from a potential peer modem. While		Peer Offer signal (Section 10.2) from a potential DLEP peer modem.
	in the Peer Discovery state, Peer Discovery signals MUST be sent		While in the Peer Discovery state, Peer Discovery signals MUST be
	repeatedly by a router, at regular intervals; every three (3) seconds		sent repeatedly by a DLEP router, at regular intervals. The interval
	with some jitter is RECOMMENDED.		MUST be a minimum of one second; it SHOULD be a configurable
			parameter. Note that this operation (sending Peer Discovery and
			waiting for Peer Offer) is outside the DLEP Transaction Model, as the
			Transaction Model only describes messages on a TCP session.
	In the Peer Discovery state, the modem waits for incoming Peer		In the Peer Discovery state, the DLEP modem implementation MUST
	Discovery signals on the DLEP well-known multicast address and port.		listen for incoming Peer Discovery signals on the DLEP well-known
	On receipt of a valid signal, it MUST unicast a Peer Offer signal to		link-local multicast address and port. The choice of using the well-
	the source address and port of the received UDP packet. Peer Offer		known IPv4 or the IPv6 well- known link-local multicast address and
	signals MAY contain the unicast address and port for TCP-based		port MUST be made by configuration. On receipt of a valid Peer
	communication with a modem, via the IPv4 Connection Point data item		Discovery signal, it MUST unicast a Peer Offer signal to the source
	(Section 10.2) or the IPv6 Connection Point data item (Section 10.3),		address and port of the received UDP packet. Peer Offer signals MAY
			contain one or more unicast address/port combinations for TCP-based
			communication with the modem, via the IPv4 Connection Point data item
			(Section 11.2) or the IPv6 Connection Point data item (Section 11.3),
	on which it is prepared to accept an incoming TCP connection. If the		on which it is prepared to accept an incoming TCP connection. If the
	modem does not include an IPv4 Connection Point data item, nor a IPv6		modem does not include an IPv4 Connection Point data item, nor a IPv6
	Connection Point data item, then the source address of the packet		Connection Point data item, then the source address of the packet
	containing the Peer Offer signal MUST be set to the address on which		containing the Peer Offer signal MUST be used as the address on which
	the modem is willing to accept TCP connections.		the modem is willing to accept TCP connections.
	The modem then begins listening for incoming TCP connections, and,		Upon establishment of a TCP connection, both modem and router enter
	having accepted one, enters the Session Initialization state.		the Session Initialization state. Anything other than Peer Discovery
	Anything other than Peer Discovery signals received on the UDP socket		signals received on the UDP socket MUST be silently dropped.
	MUST be silently dropped.
	Modems SHOULD be prepared to accept a TCP connection from a router		Modems MUST be prepared to accept a TCP connection from a router that
	that is not using the Discovery mechanism, i.e. a connection attempt		is not using the Discovery mechanism, i.e. a connection attempt that
	that occurs without a preceding Peer Discovery signal. The modem		occurs without a preceding Peer Discovery signal.
	MUST accept a TCP connection on only one (1) address/port combination
	per session.
	Routers MUST use one or more of the modem address/port combinations		Routers MUST use one or more of the modem address/port combinations
	from the Peer Offer signal or from a priori configuration to		from the Peer Offer signal or from a priori configuration to
	establish a new TCP connection to the modem. If more than one modem		establish a new TCP connection to the modem. If more than one modem
	address/port combinations is available, router implementations MAY		address/port combinations is available, router implementations MAY
	use their own heuristics to determine the order in which they are		use their own heuristics to determine the order in which they are
	tried. It is RECOMMENDED that an implementation attempt to connect		tried. It is RECOMMENDED that an implementation attempt to connect
	to any announced IPv6 address/port combinations before attempting to		to any announced IPv6 address/port combinations before attempting to
	use IPv4 combinations. If a TCP connection cannot be achieved using		use IPv4 combinations. If a TCP connection cannot be achieved using
	any of the address/port combinations and the Discovery mechanism is		any of the address/port combinations and the Discovery mechanism is
	skipping to change at page 13, line 32 ¶		skipping to change at page 14, line 20 ¶
	data items are included in the Peer Offer signal, the router MUST use		data items are included in the Peer Offer signal, the router MUST use
	the origin address of the UDP packet containing the signal as the IP		the origin address of the UDP packet containing the signal as the IP
	address, and the DLEP well-known port number.		address, and the DLEP well-known port number.
	Once a TCP connection has been established with the modem, the router		Once a TCP connection has been established with the modem, the router
	begins a new session and enters the Session Initialization state. It		begins a new session and enters the Session Initialization state. It
	is up to the router implementation if Peer Discovery signals continue		is up to the router implementation if Peer Discovery signals continue
	to be sent after the device has transitioned to the Session		to be sent after the device has transitioned to the Session
	Initialization state.		Initialization state.
	It should be noted that the peer discovery process operates using
	link-local multicast and is hence inapplicable if the potential peers
	are separated by more than one hop.
	5.2. Session Initialization State		5.2. Session Initialization State
	On entering the Session Initialization state, the router MUST send a		On entering the Session Initialization state, the router MUST send a
	Session Initialization message (Section 9.3) to the modem. The		Session Initialization message (Section 10.3) to the modem. The
	router MUST then wait for receipt of a Session Initialization		router MUST then wait for receipt of a Session Initialization
	Response message (Section 9.4) from the modem. Receipt of the		Response message (Section 10.4) from the modem. Receipt of the
	Session Initialization Response message containing a Status data item		Session Initialization Response message containing a Status data item
	(Section 10.1) with value 'Success', see Table 3, indicates that the		(Section 11.1) with value 'Success', see Table 3, indicates that the
	modem has received and processed the Session Initialization message,		modem has received and processed the Session Initialization message,
	and the router MUST transition to the In-Session state.		and the router MUST transition to the In-Session state.
	On entering the Session Initialization state, the modem MUST wait for		On entering the Session Initialization state, the modem MUST wait for
	receipt of a Session Initialization message from the router. Upon		receipt of a Session Initialization message from the router. Upon
	receipt and successful parsing of a Session Initialization message,		receipt of a Session Initialization message, the modem MUST send a
	the modem MUST send a Session Initialization Response message, and		Session Initialization Response message, and the session MUST
	the session MUST transition to the In-Session state.		transition to the In-Session state.
	DLEP provides an extension negotiation capability to be used in the		DLEP provides an extension negotiation capability to be used in the
	Session Initialization state, see Section 6. Extensions supported by		Session Initialization state, see Section 7. Extensions supported by
	an implementation MUST be declared to potential DLEP peers using the		an implementation MUST be declared to potential DLEP peers using the
	Extensions Supported data item (Section 10.6). Once both peers have		Extensions Supported data item (Section 11.6). Once both
	exchanged initialization messages, an implementation MUST NOT emit		participants have exchanged initialization messages, an
	any message, signal, data item or status code associated with an		implementation MUST NOT emit any message, signal, data item or status
	extension that was not specified in the received initialization		code associated with an extension that was not specified in the
	message from its peer.		received initialization message from its peer.
	If the router receives any message other than a valid Session		If the router receives any message other than a valid Session
	Initialization Response, it MUST send a Session Termination message		Initialization Response, it MUST send a Session Termination message
	(Section 9.7) with a relevant status code, e.g. 'Unexpected		(Section 10.7) with the 'Unexpected Message' status code, see
	Message', see Table 3, and transition to the Session Termination		Table 3, and transition to the Session Termination state.
	state.
	If the modem receives any message other than Session Initialization,		If the modem receives any message other than Session Initialization,
	or it fails to parse the received message, it MUST NOT send any		or it fails to parse the received message, it MUST NOT send any
	message, and MUST terminate the TCP connection, then restart at the		message, and MUST terminate the TCP connection and transition to the
	Peer Discovery state.		Session Reset state.
	As mentioned before, the Session Initialization Response message MUST		If an additional metric is to be introduced after the session has
	contain metric data items for all metrics that will be used during		started, the session between router and modem MUST be terminated and
	the session. If an additional metric is to be introduced after the		restarted, and the new metric described in the next Session
	session has started, the session between router and modem MUST be		Initialization Response message.
	terminated and restarted, and the new metric described in the next
	Session Initialization Response message.
	5.3. In-Session State		5.3. In-Session State
	In the In-Session state, messages can flow in both directions between		In the In-Session state, messages can flow in both directions between
	peers, indicating changes to the session state, the arrival or		participants, indicating changes to the session state, the arrival or
	departure of reachable destinations, or changes of the state of the		departure of reachable destinations, or changes of the state of the
	links to the destinations.		links to the destinations.
	In addition to the session messages, the participants will transmit
	messages concerning destinations in the network. These messages
	trigger creation/maintenance/deletion of destinations in the
	information base of the recipient. For example, a modem will inform
	its attached router of the presence of a new destination via the
	Destination Up message (Section 9.9). Receipt of a Destination Up
	causes the router to allocate the necessary resources, creating an
	entry in the information base with the specifics (i.e. MAC Address,
	Latency, Data Rate, etc.) of the destination. The loss of a
	destination is communicated via the Destination Down message
	(Section 9.11), and changes in status to the destination (e.g.,
	varying link quality, or addressing changes) are communicated via the
	Destination Update message (Section 9.13). The information on a
	given destination will persist in the router's information base until
	(1) a Destination Down message is received, indicating that the modem
	has lost contact with the remote node, or (2) the router/modem
	transitions to the Session Termination state.
	As well as receiving metrics about the link, DLEP provides a message
	allowing a router to request a different datarate or latency from the
	modem. This message is the Link Characteristics Request message
	(Section 9.15), and gives the router the ability to deal with
	requisite increases (or decreases) of allocated datarate/latency in
	demand-based schemes in a more deterministic manner.
	The In-Session state is maintained until one of the following		The In-Session state is maintained until one of the following
	conditions occur:		conditions occur:
	o The implementation terminates the session by sending a Session		o A peer terminates the session by sending a Session Termination
	Termination message (Section 9.7)), or		message (Section 10.7)), or,
	o The peer terminates the session, indicated by receiving a Session		o The peer terminates the session, indicated by receiving a Session
	Termination message.		Termination message.
	The implementation MUST then transition to the Session Termination		The peer MUST then transition to the Session Termination state.
			Prior to the exchange of Destination Up (Section 10.9) and
			Destination Up Response (Section 10.10) messages, or Destination
			Announce (Section 10.11) and Destination Announce Response
			(Section 10.12) messages, no messages concerning the logical
			destination identified by the MAC Address data item (Section 11.7)
			may be sent. A peer receiving any message with such an unannounced
			destination MUST terminate the session by issuing a Session
			Termination message (Section 10.7) with a status code of 'Invalid
			Destination', see Table 3, and transition to the Session Termination
	state.		state.
			The router receiving a Destination Up message MAY decline further
			messages concerning a given destination by sending a Destination Up
			Response with a status code of 'Not Interested'. Modems receiving
			such responses MUST NOT send further messages concerning that
			destination to the router.
			After exchanging Destination Down (Section 10.13) and Destination
			Down Response (Section 10.14) messages, no messages concerning the
			logical destination identified by the MAC Address data item may be a
			sent without previously sending a new Destination Up message. A peer
			receiving a message about a destination previously announced as
			'down' MUST terminate the session by issuing a Session Termination
			message with a status code of 'Invalid Destination' and transition to
			the Session Termination state.
	5.3.1. Heartbeats		5.3.1. Heartbeats
	In order to maintain the In-Session state, periodic Heartbeat		In order to maintain the In-Session state, periodic Heartbeat
	messages (Section 9.14) MAY be exchanged between router and modem.		messages (Section 10.16) MAY be exchanged between router and modem.
	These messages are intended to keep the session alive, and to verify		These messages are intended to keep the session alive, and to verify
	bidirectional connectivity between the two participants. Each DLEP		bidirectional connectivity between the two participants.
	peer is responsible for the creation of heartbeat messages. Receipt
	of any valid DLEP message MUST reset the heartbeat interval timer
	(i.e., valid DLEP messages take the place of, and obviate the need
	for, additional Heartbeat messages).
	Implementations SHOULD allow two (2) heartbeat intervals to expire		If Heartbeat messages are used, the following processing rules MUST
	with no traffic on the router/modem session before terminating the		apply:
	session by issuing a Session Termination message with a status code
	of 'Timed Out', and then transition to the Session Termination state.		o Each DLEP peer is responsible for the creation of heartbeat
			messages.
			o Receipt of any valid DLEP message MUST reset the heartbeat
			interval timer (i.e., valid DLEP messages take the place of, and
			obviate the need for, additional Heartbeat messages).
			o DLEP peers SHOULD allow two (2) heartbeat intervals to expire with
			no messages from the peer before terminating the session by
			issuing a Session Termination message with a status code of 'Timed
			Out', and then transition to the Session Termination state.
	5.4. Session Termination State		5.4. Session Termination State
	When a DLEP implementation enters the Session Termination state after		When a DLEP implementation enters the Session Termination state after
	sending a Session Termination message (Section 9.7) as the result of		sending a Session Termination message (Section 10.7) as the result of
	an invalid message or error, it MUST wait for a Session Termination		an invalid message or error, it MUST wait for a Session Termination
	Response message (Section 9.8) from its peer. If Heartbeat messages		Response message (Section 10.8) from its peer. If Heartbeat messages
	(Section 9.14) are in use, senders SHOULD allow four (4) heartbeat		(Section 10.16) are in use, senders SHOULD allow four (4) heartbeat
	intervals to expire before assuming that the peer is unresponsive,		intervals to expire before assuming that the peer is unresponsive,
	and continuing with session termination. If Heartbeat messages are		and continuing with session termination. If Heartbeat messages are
	not in use, then if is RECOMMENDED that an interval of eight (8)		not in use, then if is RECOMMENDED that an interval of eight (8)
	seconds be used.		seconds be used.
			When the sender of the Session Termination message receives a Session
			Termination Response message from its peer, or times out, it MUST
			transition to the Session Reset state.
	When an implementation enters the Session Termination state having		When an implementation enters the Session Termination state having
	received a Session Termination message from its peer, it MUST		received a Session Termination message from its peer, it MUST
	immediately send a Session Termination Response.		immediately send a Session Termination Response and transition to the
			Session Reset state.
	The sender and receiver of a Session Termination message MUST release
	all resources allocated for the session, and MUST eliminate all
	destinations in the information base accessible via the peer
	represented by the session. Destination Down messages (Section 9.11)
	MUST NOT be sent.
	Any messages received after either sending or receiving a Session		Any messages received after either sending or receiving a Session
	Termination message MUST be silently ignored.		Termination message MUST be silently ignored.
	Once Session Termination messages have been exchanged, or timed out,		5.5. Session Reset state
	the device MUST terminate the TCP connection to the peer, and return
	to the relevant initial state.
	6. Extensions		In the Session Reset state the implementation MUST perform the
			following actions:
	While this document represents the best efforts of the working group		o Release all resources allocated for the session.
	to be functionally complete, it is recognized that extensions to DLEP
	will in all likelihood be necessary as more link types are used.		o Eliminate all destinations in the information base accessible via
	Such extensions are defined as additional rules of behaviour,		the modem represented by the session. Destination Down messages
	messages, data items and/or status codes that are not defined in this		(Section 10.13) MUST NOT be sent.
	document.
			o Terminate the TCP connection.
			Having completed these actions the implementation SHOULD return to
			the relevant initial state: Peer Discovery for modems; either Peer
			Discovery or Session Initialization for routers, depending on
			configuration.
			5.5.1. Unexpected TCP connection termination
			If the TCP connection between peers is terminated when a participant
			is not in the Session Reset state, the implementation MUST
			immediately transition to the Session Reset state.
			6. Transaction Model
			DLEP defines a simple message transaction model: Only one request per
			destination may be in progress at a time. A message transaction is
			considered complete when a response matching a previously issued
			request is received. If a participant receives a request for a
			destination for which there is already an outstanding request, the
			implementation MUST terminate the session by issuing a Session
			Termination message (Section 10.7) with a status code of 'Unexpected
			Message', see Table 3, and transition to the Session Termination
			state. There is no restriction to the total number of message
			transactions in progress at a time, as long as each transaction
			refers to a different destination.
			It should be noted that some requests may take a considerable amount
			of time for some participants to complete, for example a modem
			handling a multicast destination up request may have to perform a
			complex network reconfiguration. A sending implementation MUST be
			able to handle such long running transactions gracefully.
			Additionally, only one session request, e.g. a Session Initialization
			message (Section 10.3) may be in progress at a time. As above, a
			session transaction is considered complete when a response matching a
			previously issued request is received. If a participant receives a
			session request while there is already a session request in progress,
			it MUST terminate the session by issuing a Session Termination
			message with a status code of 'Unexpected Message', and transition to
			the Session Termination state. Only the Session Termination message
			may be issued when a session transaction is in progress. Heartbeat
			messages (Section 10.16) MUST NOT be considered part of a session
			transaction.
			DLEP transactions do not time out and are not cancellable. An
			implementation can detect if its peer has failed in some way by use
			of the session heartbeat mechanism during the In-Session state, see
			Section 5.3.
			7. Extensions
	Extensions MUST be negotiated on a per-session basis during session		Extensions MUST be negotiated on a per-session basis during session
	initialization via the Extensions Supported mechanism.		initialization via the Extensions Supported mechanism.
	Implementations are not required to support any extension in order to		Implementations are not required to support any extension in order to
	be considered DLEP compliant. An extension document, describing the		be considered DLEP compliant. An extension document, describing the
	operation of a credit windowing scheme for flow control, is described		operation of a credit windowing scheme for flow control, is described
	in [CREDIT].		in [CREDIT].
	If interoperable protocol extensions are required, they MUST be		If interoperable protocol extensions are required, they MUST be
	standardized either as an update to this document, or as an		standardized either as an update to this document, or as an
	additional stand-alone specification. The requests for IANA-		additional stand-alone specification. The requests for IANA-
	controlled registries in this document contain sufficient Reserved		controlled registries in this document contain sufficient Reserved
	space for DLEP signals, messages, data items and status codes to		space for DLEP signals, messages, data items and status codes to
	accommodate future extensions to the protocol.		accommodate future extensions to the protocol.
	As multiple protocol extensions MAY be announced during session		As multiple protocol extensions MAY be announced during session
	initialization, authors of protocol extensions MUST consider the		initialization, authors of protocol extensions MUST consider the
	interaction of their extension with other published extensions, and		interaction of their extension with other published extensions, and
	specify any incompatibilities.		specify any incompatibilities.
	6.1. Experiments		7.1. Experiments
	This document requests Private Use numbering space in the DLEP		This document requests Private Use numbering space in the DLEP
	signal/message, data item and status code registries for experimental		signal/message, data item and status code registries for experimental
	extensions. The intent is to allow for experimentation with new		extensions. The intent is to allow for experimentation with new
	signals, messages, data items, and/or status codes, while still		signals, messages, data items, and/or status codes, while still
	retaining the documented DLEP behavior.		retaining the documented DLEP behavior.
	Use of the Private Use signals, messages, data items, status codes,		Use of the Private Use signals, messages, data items, status codes,
	or behaviors MUST be announced as DLEP Extensions, during session		or behaviors MUST be announced as DLEP Extensions, during session
	initialization, using extension identifiers from the Private Use		initialization, using extension identifiers from the Private Use
	skipping to change at page 17, line 30 ¶		skipping to change at page 19, line 19 ¶
	Multiple experiments MAY be announced in the Session Initialization		Multiple experiments MAY be announced in the Session Initialization
	messages. However, use of multiple experiments in a single session		messages. However, use of multiple experiments in a single session
	could lead to interoperability issues or unexpected results (e.g.,		could lead to interoperability issues or unexpected results (e.g.,
	clashes of experimental signals, messages, data items and/or status		clashes of experimental signals, messages, data items and/or status
	code types), and is therefore discouraged. It is left to		code types), and is therefore discouraged. It is left to
	implementations to determine the correct processing path (e.g., a		implementations to determine the correct processing path (e.g., a
	decision on whether to terminate the session, or to establish a		decision on whether to terminate the session, or to establish a
	precedence of the conflicting definitions) if such conflicts arise.		precedence of the conflicting definitions) if such conflicts arise.
	7. Scalability		8. Scalability
	The protocol is intended to support thousands of destinations on a		The protocol is intended to support thousands of destinations on a
	given modem/router pair. At large scale, implementations SHOULD		given modem/router pair. At large scale, implementations SHOULD
	consider employing techniques to prevent flooding a peer with a large		consider employing techniques to prevent flooding a peer with a large
	number of messages in a short time. It is recommended that		number of messages in a short time. It is recommended that
	implementations consider a dampening algorithm to prevent a flapping		implementations consider a dampening algorithm to prevent a flapping
	device from generating a large number of Destination Up/Destination		device from generating a large number of Destination Up/Destination
	Down messages, for example. Implementations SHOULD also consider		Down messages, for example. Implementations SHOULD also consider
	techniques such as a hysteresis to lessen the impact of rapid, minor		techniques such as a hysteresis to lessen the impact of rapid, minor
	fluctuations in link quality. The specific algorithms to be used for		fluctuations in link quality. The specific algorithms to be used for
	handling flapping destinations and minor changes in link quality are		handling flapping destinations and minor changes in link quality are
	outside the scope of this specification.		outside the scope of this specification.
	8. DLEP Signal and Message Structure		9. DLEP Signal and Message Structure
	DLEP defines two protocol units used in two different ways: Signals		DLEP defines two protocol units used in two different ways: Signals
	and Messages. Signals are only used in the Discovery mechanism and		and Messages. Signals are only used in the Discovery mechanism and
	are carried in UDP datagrams. Messages are used bi-directionally		are carried in UDP datagrams. Messages are used bi-directionally
	over a TCP connection between two peers, in the Session		over a TCP connection between two peers, in the Session
	Initialization, In-Session and Session Termination states.		Initialization, In-Session and Session Termination states.
	Both signals and messages consist of a header followed by an		Both signals and messages consist of a header followed by an
	unordered list of data items. Headers consist of Type and Length		unordered list of data items. Headers consist of Type and Length
	information, while data items are encoded as TLV (Type-Length-Value)		information, while data items are encoded as TLV (Type-Length-Value)
	skipping to change at page 18, line 20 ¶		skipping to change at page 20, line 8 ¶
	message.		message.
	There is no restriction on the order of data items following a		There is no restriction on the order of data items following a
	header, and the multiplicity of duplicate data items is defined by		header, and the multiplicity of duplicate data items is defined by
	the definition of the signal or message declared by the type in the		the definition of the signal or message declared by the type in the
	header.		header.
	All integers in header fields and values MUST be in network byte-		All integers in header fields and values MUST be in network byte-
	order.		order.
	8.1. DLEP Signal Header		9.1. DLEP Signal Header
	The DLEP signal header contains the following fields:		The DLEP signal header contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| 'D' | 'L' | 'E' | 'P' |		| 'D' | 'L' | 'E' | 'P' |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Signal Type | Length |		| Signal Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 18, line 50 ¶		skipping to change at page 20, line 38 ¶
	Length: The length in octets, expressed as a 16-bit unsigned		Length: The length in octets, expressed as a 16-bit unsigned
	integer, of all of the DLEP data items associated with this		integer, of all of the DLEP data items associated with this
	signal. This length SHALL NOT include the length of the header		signal. This length SHALL NOT include the length of the header
	itself.		itself.
	The DLEP signal header is immediately followed by one or more DLEP		The DLEP signal header is immediately followed by one or more DLEP
	data items, encoded in TLVs, as defined in this document.		data items, encoded in TLVs, as defined in this document.
	If an unrecognized, or unexpected signal is received, or a received		If an unrecognized, or unexpected signal is received, or a received
	signal contains unrecognized, invalid, or disallowed duplicate data		signal contains unrecognized, invalid, or disallowed duplicate data
	items, the receiving peer MUST ignore the signal.		items, the receiving participant MUST ignore the signal.
	8.2. DLEP Message Header		9.2. DLEP Message Header
	The DLEP message header contains the following fields:		The DLEP message header contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Message Type | Length |		| Message Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 4: DLEP Message Header		Figure 4: DLEP Message Header
	skipping to change at page 19, line 30 ¶		skipping to change at page 21, line 18 ¶
	Length: The length in octets, expressed as a 16-bit unsigned		Length: The length in octets, expressed as a 16-bit unsigned
	integer, of all of the DLEP data items associated with this		integer, of all of the DLEP data items associated with this
	message. This length SHALL NOT include the length of the header		message. This length SHALL NOT include the length of the header
	itself.		itself.
	The DLEP message header is immediately followed by one or more DLEP		The DLEP message header is immediately followed by one or more DLEP
	data items, encoded in TLVs, as defined in this document.		data items, encoded in TLVs, as defined in this document.
	If an unrecognized, or unexpected message is received, or a received		If an unrecognized, or unexpected message is received, or a received
	message contains unrecognized, invalid, or disallowed duplicate data		message contains unrecognized, invalid, or disallowed duplicate data
	items, the receiving peer MUST issue a Session Termination message		items, the receiving participant MUST issue a Session Termination
	(Section 9.7) with a Status data item (Section 10.1) containing the		message (Section 10.7) with a Status data item (Section 11.1)
	most relevant status code, and transition to the Session Termination		containing the most relevant status code, see Table 3, and transition
	state.		to the Session Termination state.
	8.3. DLEP Generic Data Item		9.3. DLEP Generic Data Item
	All DLEP data items contain the following fields:		All DLEP data items contain the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Value... :		| Value... :
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 20, line 12 ¶		skipping to change at page 21, line 47 ¶
	Data Item Type: An 16-bit unsigned integer field specifying the type		Data Item Type: An 16-bit unsigned integer field specifying the type
	of data item being sent.		of data item being sent.
	Length: The length in octets, expressed as an 16-bit unsigned		Length: The length in octets, expressed as an 16-bit unsigned
	integer, of the value field of the data item. This length SHALL		integer, of the value field of the data item. This length SHALL
	NOT include the length of the header itself.		NOT include the length of the header itself.
	Value: A field of <Length> octets, which contains data specific to a		Value: A field of <Length> octets, which contains data specific to a
	particular data item.		particular data item.
	9. DLEP Signals and Messages		10. DLEP Signals and Messages
	As mentioned above, all DLEP signals begin with the DLEP signal		As mentioned above, all DLEP signals begin with the DLEP signal
	header, and all DLEP messages begin with the DLEP message header.		header, and all DLEP messages begin with the DLEP message header.
	Therefore, in the following descriptions of specific signals and		Therefore, in the following descriptions of specific signals and
	messages, this header is assumed, and will not be replicated.		messages, this header is assumed, and will not be replicated.
	Following is the set of core signals and messages that MUST be		Following is the set of core signals and messages that MUST be
	recognized by a DLEP compliant implementation. As mentioned before,		recognized by a DLEP compliant implementation. As mentioned before,
	not all messages may be used during a session, but an implementation		not all messages may be used during a session, but an implementation
	MUST correctly process these messages when received.		MUST correctly process these messages when received.
	The core DLEP signals and messages are:		The core DLEP signals and messages are:
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	| Type Code | Description |		| Type Code | Description |
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	| 0 | Reserved |		| 0 | Reserved |
	| 1 | Peer Discovery signal (Section 9.1) |		| 1 | Peer Discovery signal (Section 10.1) |
	| 2 | Peer Offer signal (Section 9.2) |		| 2 | Peer Offer signal (Section 10.2) |
	| 3 | Session Initialization message (Section 9.3) |		| 3 | Session Initialization message (Section 10.3) |
	| 4 | Session Initialization Response message (Section |		| 4 | Session Initialization Response message (Section |
	| | 9.4) |		| | 10.4) |
	| 5 | Session Update message (Section 9.5) |		| 5 | Session Update message (Section 10.5) |
	| 6 | Session Update Response message (Section 9.6) |		| 6 | Session Update Response message (Section 10.6) |
	| 7 | Session Termination message (Section 9.7) |		| 7 | Session Termination message (Section 10.7) |
	| 8 | Session Termination Response message (Section 9.8) |		| 8 | Session Termination Response message (Section 10.8) |
	| 9 | Destination Up message (Section 9.9) |		| 9 | Destination Up message (Section 10.9) |
	| 10 | Destination Up Response message (Section 9.10) |		| 10 | Destination Up Response message (Section 10.10) |
	| 11 | Destination Down message (Section 9.11) |		| 11 | Destination Down message (Section 10.13) |
	| 12 | Destination Down Response message (Section 9.12) |		| 12 | Destination Down Response message (Section 10.14) |
	| 13 | Destination Update message (Section 9.13) |		| 13 | Destination Update message (Section 10.15) |
	| 14 | Heartbeat message (Section 9.14) |		| 14 | Heartbeat message (Section 10.16) |
	| 15 | Link Characteristics Request message (Section 9.15) |		| 15 | Link Characteristics Request message (Section |
			| | 10.17) |
	| 16 | Link Characteristics Response message (Section |		| 16 | Link Characteristics Response message (Section |
	| | 9.16) |		| | 10.18) |
	| 17-65519 | Reserved for future extensions |		| 17 | Destination Announce message (Section 10.11) |
			| 18 | Destination Announce Response message (Section |
			| | 10.12) |
			| 19-65519 | Reserved for future extensions |
	| 65520-65534 | Private Use. Available for experiments |		| 65520-65534 | Private Use. Available for experiments |
	| 65535 | Reserved |		| 65535 | Reserved |
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	Table 1: DLEP Signal/Message types		Table 1: DLEP Signal/Message types
	9.1. Peer Discovery Signal		10.1. Peer Discovery Signal
	A Peer Discovery signal SHOULD be sent by a router to discover DLEP		A Peer Discovery signal SHOULD be sent by a DLEP router to discover
	modems in the network. The Peer Offer signal (Section 9.2) is		DLEP modems in the network. The Peer Offer signal (Section 10.2) is
	required to complete the discovery process. Implementations MAY		required to complete the discovery process. Implementations MUST
	implement their own retransmit heuristics in cases where it is		implement their own retransmit heuristics in cases where it is
	determined the Peer Discovery signal has timed out.		determined the Peer Discovery signal has timed out.
	To construct a Peer Discovery signal, the Signal Type value in the		To construct a Peer Discovery signal, the Signal Type value in the
	signal header is set to 1, from Table 1.		signal header is set to 1, from Table 1.
	The Peer Discovery signal MAY contain the following data item:		The Peer Discovery signal MAY contain the following data item:
	o Peer Type (Section 10.4)		o Peer Type (Section 11.4)
	9.2. Peer Offer Signal		10.2. Peer Offer Signal
	A Peer Offer signal MUST be sent by a DLEP modem in response to a		A Peer Offer signal MUST be sent by a DLEP modem in response to a
	valid Peer Discovery signal (Section 9.1).		valid Peer Discovery signal (Section 10.1).
	The Peer Offer signal MUST be sent to the unicast address of the		The Peer Offer signal MUST be sent to the unicast address of the
	originator of the Peer Discovery signal.		originator of the Peer Discovery signal.
	To construct a Peer Offer signal, the Signal Type value in the signal		To construct a Peer Offer signal, the Signal Type value in the signal
	header is set to 2, from Table 1.		header is set to 2, from Table 1.
	The Peer Offer signal MAY contain the following data item:		The Peer Offer signal MAY contain the following data item:
	o Peer Type (Section 10.4)		o Peer Type (Section 11.4)
	The Peer Offer signal MAY contain one or more of any of the following		The Peer Offer signal MAY contain one or more of any of the following
	data items, with different values:		data items, with different values:
	o IPv4 Connection Point (Section 10.2)		o IPv4 Connection Point (Section 11.2)
	o IPv6 Connection Point (Section 10.3)		o IPv6 Connection Point (Section 11.3)
	The IP Connection Point data items indicate the unicast address the		The IP Connection Point data items indicate the unicast address the
	receiver of Peer Offer MUST use when connecting the DLEP TCP session.		router MUST use when connecting the DLEP TCP session. If multiple IP
	If multiple IP Connection Point data items are present in the Peer		Connection Point data items are present in the Peer Offer signal,
	Offer signal, implementations MAY use their own heuristics to select		router implementations MAY use their own heuristics to select the
	the address to connect to. If no IP Connection Point data items are		address to connect to. If no IP Connection Point data items are
	included in the Peer Offer signal, the receiver MUST use the origin		included in the Peer Offer signal, the router MUST use the origin
	address of the signal as the IP address, and the DLEP well-known port		address of the signal as the IP address, and the DLEP well-known port
	number (Section 12.7) to establish the TCP connection.		number (Section 13.6) to establish the TCP connection.
	9.3. Session Initialization Message		10.3. Session Initialization Message
	A Session Initialization message MUST be sent by a router as the		A Session Initialization message MUST be sent by a DLEP router as the
	first message of the DLEP TCP session. It is sent by the router		first message of the DLEP TCP session. It is sent by the router
	after a TCP connect to an address/port combination that was obtained		after a TCP connect to an address/port combination that was obtained
	either via receipt of a Peer Offer, or from a priori configuration.		either via receipt of a Peer Offer, or from a priori configuration.
	If any optional extensions are supported by the implementation, they		If any optional extensions are supported by the implementation, they
	MUST be enumerated in the Extensions Supported data item. If an		MUST be enumerated in the Extensions Supported data item. If an
	Extensions Supported data item does not exist in a Session		Extensions Supported data item does not exist in a Session
	Initialization message, the receiver of the message MUST conclude		Initialization message, the modem MUST conclude that there is no
	that there is no support for extensions in the sender.		support for extensions in the router.
	Implementations supporting the Heartbeat Interval (Section 10.5)		Implementations supporting the Heartbeat Interval (Section 11.5)
	should understand that heartbeats are not fully established until		should understand that heartbeats are not fully established until
	receipt of Session Initialization Response message (Section 9.4), and		receipt of Session Initialization Response message (Section 10.4),
	should therefore implement their own timeout and retry heuristics for		and should therefore implement their own timeout and retry heuristics
	this message.		for this message.
	To construct a Session Initialization message, the Message Type value		To construct a Session Initialization message, the Message Type value
	in the message header is set to 3, from Table 1.		in the message header is set to 3, from Table 1.
	The Session Initialization message MUST contain one of each of the		The Session Initialization message MUST contain one of each of the
	following data items:		following data items:
	o Heartbeat Interval (Section 10.5)		o Heartbeat Interval (Section 11.5)
	The Session Initialization message MAY contain one of each of the		The Session Initialization message MAY contain one of each of the
	following data items:		following data items:
	o Peer Type (Section 10.4)		o Peer Type (Section 11.4)
	o Extensions Supported (Section 10.6)		o Extensions Supported (Section 11.6)
	A Session Initialization message MUST be acknowledged by the receiver		A Session Initialization message MUST be acknowledged by the modem
	issuing a Session Initialization Response message (Section 9.4).		issuing a Session Initialization Response message (Section 10.4).
	As an exception to the general rule that an implementation receiving		As an exception to the general rule that an implementation receiving
	an unrecognized data item in a message terminating the session with		an unrecognized data item in a message terminating the session with
	an error, see Section 8.2, if a Session Initialization message		an error, see Section 9.2, if a Session Initialization message
	contains one or more Extension Supported data items announcing		contains one or more Extension Supported data items announcing
	support for extensions that the implementation does not recognize,		support for extensions that the implementation does not recognize,
	then the implementation MAY ignore data items it does not recognize.		then the implementation MAY ignore data items it does not recognize.
	9.4. Session Initialization Response Message		10.4. Session Initialization Response Message
	A Session Initialization Response message MUST be sent in response to		A Session Initialization Response message MUST be sent in response to
	a received Session Initialization message (Section 9.3). The Session		a received Session Initialization message (Section 10.3). The
	Initialization Response message completes the DLEP session		Session Initialization Response message completes the DLEP session
	establishment; the sender of the message should transition to the In-		establishment; the modem should transition to the In-Session state
	Session state when the message is sent, and the receiver should		when the message is sent, and the router should transition to the In-
	transition to the In-Session state upon receipt (and successful		Session state upon receipt of an acceptable Session Initialization
	parsing) of an acceptable Session Initialization Response message.		Response message.
	All supported metric data items MUST be included in the Session		All supported metric data items MUST be included in the Session
	Initialization Response message, with default values to be used on a		Initialization Response message, with default values to be used on a
	'modem-wide' basis. This can be viewed as the modem 'declaring' all		'modem-wide' basis. This can be viewed as the modem 'declaring' all
	supported metrics at DLEP session initialization. Receipt of any		supported metrics at DLEP session initialization. Receipt of any
	DLEP message containing a metric data item not included in the		DLEP message containing a metric data item not included in the
	Session Initialization Response message MUST be treated as an error,		Session Initialization Response message MUST be treated as an error,
	resulting in the termination of the DLEP session between router and		resulting in the termination of the DLEP session between router and
	modem.		modem.
	If any optional extensions are supported by the modem, they MUST be		If any optional extensions are supported by the modem, they MUST be
	enumerated in the Extensions Supported data item. If an Extensions		enumerated in the Extensions Supported data item. If an Extensions
	Supported data item does not exist in a Session Initialization		Supported data item does not exist in a Session Initialization
	Response message, the receiver of the message MUST conclude that		Response message, the router MUST conclude that there is no support
	there is no support for extensions in the sender.		for extensions in the modem.
	After the Session Initialization/Session Initialization Response		After the Session Initialization/Session Initialization Response
	messages have been successfully exchanged, implementations MUST only		messages have been successfully exchanged, implementations MUST only
	use extensions that are supported by BOTH peers.		use extensions that are supported by BOTH participants.
	To construct a Session Initialization Response message, the Message		To construct a Session Initialization Response message, the Message
	Type value in the message header is set to 4, from Table 1.		Type value in the message header is set to 4, from Table 1.
	The Session Initialization Response message MUST contain one of each		The Session Initialization Response message MUST contain one of each
	of the following data items:		of the following data items:
	o Heartbeat Interval (Section 10.5)		o Heartbeat Interval (Section 11.5)
	o Maximum Data Rate (Receive) (Section 10.12)		o Maximum Data Rate (Receive) (Section 11.12)
	o Maximum Data Rate (Transmit) (Section 10.13)		o Maximum Data Rate (Transmit) (Section 11.13)
	o Current Data Rate (Receive) (Section 10.14)		o Current Data Rate (Receive) (Section 11.14)
	o Current Data Rate (Transmit) (Section 10.15)		o Current Data Rate (Transmit) (Section 11.15)
	o Latency (Section 10.16)		o Latency (Section 11.16)
	The Session Initialization Response message MUST contain one of each		The Session Initialization Response message MUST contain one of each
	of the following data items, if the data item will be used during the		of the following data items, if the data item will be used during the
	lifetime of the session:		lifetime of the session:
	o Resources (Receive) (Section 10.17)		o Resources (Receive) (Section 11.17)
	o Resources (Transmit) (Section 10.18)		o Resources (Transmit) (Section 11.18)
	o Relative Link Quality (Receive) (Section 10.19)		o Relative Link Quality (Receive) (Section 11.19)
	o Relative Link Quality (Transmit) (Section 10.20)		o Relative Link Quality (Transmit) (Section 11.20)
			o Maximum Transmission Unit (MTU) (Section 11.21)
	The Session Initialization Response message MAY contain one of each		The Session Initialization Response message MAY contain one of each
	of the following data items:		of the following data items:
	o Status (Section 10.1)		o Status (Section 11.1)
	o Peer Type (Section 10.4)		o Peer Type (Section 11.4)
	o Extensions Supported (Section 10.6)		o Extensions Supported (Section 11.6)
	A receiver of a Session Initialization Response message without a
	Status data item MUST behave as if a Status data item with code
	'Success' had been received.
	9.5. Session Update Message		A router receiving a Session Initialization Response message without
			a Status data item MUST behave as if a Status data item with code
			'Success' had been received, see Table 3.
	A Session Update message MAY be sent by a DLEP peer to indicate local		10.5. Session Update Message
	Layer 3 address changes, or metric changes on a modem-wide basis.
	For example, addition of an IPv4 address to the router MAY prompt a		A Session Update message MAY be sent by a DLEP participant to
	Session Update message to its attached DLEP modems. Also, for		indicate local Layer 3 address changes, or metric changes on a modem-
	example, a modem that changes its Maximum Data Rate (Receive) for all		wide basis. It should be noted that Session Update messages can be
	destinations MAY reflect that change via a Session Update message to		sent by both routers and modems. For example, addition of an IPv4
	its attached router(s).		address to the router MAY prompt a Session Update message to its
			attached modems. Also, for example, a modem that changes its Maximum
			Data Rate (Receive) for all destinations MAY reflect that change via
			a Session Update message to its attached router(s).
	Concerning Layer 3 addresses: If the modem is capable of		Concerning Layer 3 addresses: If the modem is capable of
	understanding and forwarding this information (via proprietary		understanding and forwarding this information (via proprietary
	mechanisms), the address update would prompt any remote DLEP modems		mechanisms), the address update would prompt any remote DLEP modems
	(DLEP-enabled modems in a remote node) to issue a Destination Update		(DLEP-enabled modems in a remote node) to issue a Destination Update
	message (Section 9.13) to their local routers with the new (or		message (Section 10.15) to their local routers with the new (or
	deleted) addresses. Modems that do not track Layer 3 addresses		deleted) addresses. Modems that do not track Layer 3 addresses
	SHOULD silently parse and ignore Layer 3 data items. The Session		SHOULD silently parse and ignore Layer 3 data items. The Session
	Update message MUST be acknowledged with a Session Update Response		Update message MUST be acknowledged with a Session Update Response
	message (Section 9.6).		message (Section 10.6).
	If metrics are supplied with the Session Update message (e.g.,		If metrics are supplied with the Session Update message (e.g.,
	Maximum Data Rate), these metrics are considered to be modem-wide,		Maximum Data Rate), these metrics are considered to be modem-wide,
	and therefore MUST be applied to all destinations in the information		and therefore MUST be applied to all destinations in the information
	base associated with the router/modem session.		base associated with the DLEP session.
	To construct a Session Update message, the Message Type value in the		To construct a Session Update message, the Message Type value in the
	message header is set to 5, from Table 1.		message header is set to 5, from Table 1.
	The Session Update message MAY contain one of each of the following		The Session Update message MAY contain one of each of the following
	data items:		data items:
	o Maximum Data Rate (Receive) (Section 10.12)		o Maximum Data Rate (Receive) (Section 11.12)
			o Maximum Data Rate (Transmit) (Section 11.13)
	o Maximum Data Rate (Transmit) (Section 10.13)		o Current Data Rate (Receive) (Section 11.14)
	o Current Data Rate (Receive) (Section 10.14)		o Current Data Rate (Transmit) (Section 11.15)
	o Current Data Rate (Transmit) (Section 10.15)		o Latency (Section 11.16)
	o Latency (Section 10.16)		The Session Update message MAY contain one of each of the following
			data items, if the data item is in use by the session:
	o Resources (Receive) (Section 10.17)		o Resources (Receive) (Section 11.17)
	o Resources (Transmit) (Section 10.18)		o Resources (Transmit) (Section 11.18)
	o Relative Link Quality (Receive) (Section 10.19)
	o Relative Link Quality (Transmit) (Section 10.20)		o Relative Link Quality (Receive) (Section 11.19)
			o Relative Link Quality (Transmit) (Section 11.20)
			o Maximum Transmission Unit (MTU) (Section 11.21)
	The Session Update message MAY contain one or more of the following		The Session Update message MAY contain one or more of the following
	data items, with different values:		data items, with different values:
	o IPv4 Address (Section 10.8)		o IPv4 Address (Section 11.8)
	o IPv6 Address (Section 10.9)		o IPv6 Address (Section 11.9)
	A Session Update message MUST be acknowledged by the receiver issuing		A Session Update message MUST be acknowledged by the receiver issuing
	a Session Update Response message (Section 9.6).		a Session Update Response message (Section 10.6).
	9.6. Session Update Response Message		10.6. Session Update Response Message
	A Session Update Response message MUST be sent by implementations to		A Session Update Response message MUST be sent by implementations to
	indicate whether a Session Update message (Section 9.5) was		indicate whether a Session Update message (Section 10.5) was
	successfully received.		successfully received.
	To construct a Session Update Response message, the Message Type		To construct a Session Update Response message, the Message Type
	value in the message header is set to 6, from Table 1.		value in the message header is set to 6, from Table 1.
	The Session Update Response message MAY contain one of each of the		The Session Update Response message MAY contain one Status
	following data items:		(Section 11.1) data item.
	o Status (Section 10.1)
	A receiver of a Session Update Response message without a Status data		A receiver of a Session Update Response message without a Status data
	item MUST behave as if a Status data item with code 'Success' had		item MUST behave as if a Status data item with status code 'Success'
	been received.		had been received, see Table 3.
	9.7. Session Termination Message		10.7. Session Termination Message
	A Session Termination message MUST be sent by a DLEP participant when		A Session Termination message MUST be sent by a participant when the
	the router/modem session needs to be terminated.		DLEP session needs to be terminated. It should be noted that Session
			Termination messages can be sent by both routers and modems.
	To construct a Session Termination message, the Message Type value in		To construct a Session Termination message, the Message Type value in
	the message header is set to 7, from Table 1.		the message header is set to 7, from Table 1.
	The Session Termination message MAY contain one of each of the		The Session Termination message MAY contain one Status (Section 11.1)
	following data items:		data item.
	o Status (Section 10.1)
	A receiver of a Session Termination message without a Status data		A receiver of a Session Termination message without a Status data
	item MUST behave as if a Status of 'Unknown reason for Session		item MUST behave as if a Status data item with status code 'Success',
	Termination' has been received.		see Table 3, implying graceful termination, had been received.
	A Session Termination message MUST be acknowledged by the receiver		A Session Termination message MUST be acknowledged by the receiver
	issuing a Session Termination Response message (Section 9.8).		issuing a Session Termination Response message (Section 10.8).
	9.8. Session Termination Response Message		10.8. Session Termination Response Message
	A Session Termination Response message MUST be sent by a DLEP peer in		A Session Termination Response message MUST be sent by a DLEP
	response to a received Session Termination message (Section 9.7).		participant in response to a received Session Termination message
			(Section 10.7).
	Receipt of a Session Termination Response message completes the		Receipt of a Session Termination Response message completes the tear-
	teardown of the router/modem session.		down of the DLEP session.
	To construct a Session Termination Response message, the Message Type		To construct a Session Termination Response message, the Message Type
	value in the message header is set to 8, from Table 1.		value in the message header is set to 8, from Table 1.
	The Session Termination Response message MAY contain one of each of		The Session Termination Response message MAY contain one Status
	the following data items:		(Section 11.1) data item.
	o Status (Section 10.1)
	A receiver of a Session Termination Response message without a Status		A receiver of a Session Termination Response message without a Status
	data item MUST behave as if a Status data item with status code		data item MUST behave as if a Status data item with status code
	'Success', implying graceful termination, had been received.		'Success', see Table 3, implying graceful termination, had been
			received.
	9.9. Destination Up Message
	A Destination Up message can be sent either by the modem, to indicate		10.9. Destination Up Message
	that a new remote node has been detected, or by the router, to
	indicate the presence of a new logical destination (e.g., a Multicast
	group) in the network.
	A Destination Up message MUST be acknowledged by the receiver issuing		A Destination Up message MUST be sent by the modem to indicate that a
	a Destination Up Response message (Section 9.10). When a Destination		new destination has been detected. A Destination Up message MUST be
	Up message is received and successfully processed, the receiver		acknowledged by the router issuing a Destination Up Response message
	should add knowledge of the new destination to its information base,		(Section 10.10). When a Destination Up message is received and
	indicating that the destination is accessible via the modem/router		successfully processed, the router should add knowledge of the new
	pair.		destination to its information base, indicating that the destination
			is accessible via the modem.
	To construct a Destination Up message, the Message Type value in the		To construct a Destination Up message, the Message Type value in the
	message header is set to 9, from Table 1.		message header is set to 9, from Table 1.
	The Destination Up message MUST contain one of each of the following		The Destination Up message MUST contain one of each of the following
	data items:		data items:
	o MAC Address (Section 10.7)		o MAC Address (Section 11.7)
	The Destination Up message MAY contain one of each of the following		The Destination Up message MAY contain one of each of the following
	data items:		data items:
	o Maximum Data Rate (Receive) (Section 10.12)		o Maximum Data Rate (Receive) (Section 11.12)
	o Maximum Data Rate (Transmit) (Section 10.13)		o Maximum Data Rate (Transmit) (Section 11.13)
	o Current Data Rate (Receive) (Section 10.14)		o Current Data Rate (Receive) (Section 11.14)
	o Current Data Rate (Transmit) (Section 10.15)		o Current Data Rate (Transmit) (Section 11.15)
	o Latency (Section 10.16)		o Latency (Section 11.16)
	o Resources (Receive) (Section 10.17)		The Destination Up message MAY contain one of each of the following
			data items, if the data item is in use by the session:
	o Resources (Transmit) (Section 10.18)		o Resources (Receive) (Section 11.17)
	o Relative Link Quality (Receive) (Section 10.19)		o Resources (Transmit) (Section 11.18)
	o Relative Link Quality (Transmit) (Section 10.20)		o Relative Link Quality (Receive) (Section 11.19)
			o Relative Link Quality (Transmit) (Section 11.20)
			o Maximum Transmission Unit (MTU) (Section 11.21)
	The Destination Up message MAY contain one or more of the following		The Destination Up message MAY contain one or more of the following
	data items, with different values:		data items, with different values:
	o IPv4 Address (Section 10.8)		o IPv4 Address (Section 11.8)
	o IPv6 Address (Section 10.9)		o IPv6 Address (Section 11.9)
	o IPv4 Attached Subnet (Section 10.10)		o IPv4 Attached Subnet (Section 11.10)
	o IPv6 Attached Subnet (Section 10.11)		o IPv6 Attached Subnet (Section 11.11)
	If the sender has IPv4 and/or IPv6 address information for a		If the modem has IPv4 and/or IPv6 address information for a
	destination it SHOULD include the relevant data items in the		destination it SHOULD include the relevant data items in the
	Destination Up message, reducing the need for the receiver to probe		Destination Up message, reducing the need for the router to probe for
	for any address.		any address.
	9.10. Destination Up Response Message		10.10. Destination Up Response Message
	A DLEP participant MUST send a Destination Up Response message to		A DLEP router MUST send a Destination Up Response message to indicate
	indicate whether a Destination Up message (Section 9.9) was		whether a Destination Up message (Section 10.9) was successfully
	successfully processed.		processed.
	To construct a Destination Up Response message, the Message Type		To construct a Destination Up Response message, the Message Type
	value in the message header is set to 10, from Table 1.		value in the message header is set to 10, from Table 1.
	The Destination Up Response message MUST contain one of each of the		The Destination Up Response message MUST contain one MAC Address
	following data items:		(Section 11.7) data item.
	o MAC Address (Section 10.7)		The Destination Up Response message MAY contain one Status
	The Destination Up Response message MAY contain one of each of the		(Section 11.1) data item.
			A modem receiving a Destination Up Response message without a Status
			data item MUST behave as if a Status data item with status code
			'Success' had been received, see Table 3.
			10.11. Destination Announce Message
			If a router wishes to request information concerning a destination
			that has not yet been announced by a mode via a Destination Up
			message (Section 10.9), it MAY send a Destination Announce message to
			the modem.
			A Destination Announce message MUST be acknowledged by the modem
			issuing a Destination Announce Response message (Section 10.12).
			To construct a Destination Announce message, the Message Type value
			in the message header is set to 17, from Table 1.
			The Destination Announce message MUST contain one of each of the
	following data items:		following data items:
	o Status (Section 10.1)		o MAC Address (Section 11.7)
	A receiver of a Destination Up Response message without a Status data		The Destination Announce message MAY contain zero or more of the
	item MUST behave as if a Status data item with status code 'Success'		following data items, with different values:
	had been received.
	9.11. Destination Down Message		o IPv4 Address (Section 11.8)
	A DLEP peer MUST send a Destination Down message to report when a		o IPv6 Address (Section 11.9)
	destination (a remote node or a multicast group) is no longer
	reachable. A Destination Down Response message (Section 9.12) MUST		10.12. Destination Announce Response Message
			A DLEP modem MUST send a Destination Announce Response message to
			indicate whether a Destination Announce message (Section 10.11) was
			successfully processed and the destination identified by the MAC
			Address data item is available.
			When a Destination Announce Response message is received and
			successfully processed, the router should add knowledge of the new
			destination to its information base, indicating that the destination
			is accessible via the modem.
			To construct a Destination Announce Response message, the Message
			Type value in the message header is set to 18, from Table 1.
			The Destination Announce Response message MUST contain one of each of
			the following data items:
			o MAC Address (Section 11.7)
			The Destination Announce Response message MAY contain one of each of
			the following data items:
			o Maximum Data Rate (Receive) (Section 11.12)
			o Maximum Data Rate (Transmit) (Section 11.13)
			o Current Data Rate (Receive) (Section 11.14)
			o Current Data Rate (Transmit) (Section 11.15)
			o Latency (Section 11.16)
			The Destination Announce Response message MAY contain one of each of
			the following data items, if the data item is in use by the session:
			o Resources (Receive) (Section 11.17)
			o Resources (Transmit) (Section 11.18)
			o Relative Link Quality (Receive) (Section 11.19)
			o Relative Link Quality (Transmit) (Section 11.20)
			o Maximum Transmission Unit (MTU) (Section 11.21)
			The Destination Announce Response message MAY contain zero or more of
			the following data items, with different values:
			o IPv4 Address (Section 11.8)
			o IPv6 Address (Section 11.9)
			If the modem has IPv4 and/or IPv6 address information for a
			destination it SHOULD include the relevant data items in the
			Destination Announce Response message, reducing the need for the
			router to probe for any address.
			o Status (Section 11.1)
			A router receiving a Destination Announce Response message without a
			Status data item MUST behave as if a Status data item with status
			code 'Success' had been received, see Table 3.
			If a modem does not support Destination Announce messages, or the
			modem is unable to report information immediately about the requested
			information, if the destination is not currently accessible, for
			example, the status code in the Status data item SHOULD be set to
			'Request Denied'.
			10.13. Destination Down Message
			A DLEP participant MUST send a Destination Down message to report
			when a destination (a remote node or a multicast group) is no longer
			reachable. A Destination Down Response message (Section 10.14) MUST
	be sent by the recipient of a Destination Down message to confirm		be sent by the recipient of a Destination Down message to confirm
	that the relevant data has been removed from the information base.		that the relevant data has been removed from the information base.
	To construct a Destination Down message, the Message Type value in		To construct a Destination Down message, the Message Type value in
	the message header is set to 11, from Table 1.		the message header is set to 11, from Table 1.
	The Destination Down message MUST contain one of each of the		The Destination Down message MUST contain one of each of the
	following data items:		following data items:
	o MAC Address (Section 10.7)		o MAC Address (Section 11.7)
	9.12. Destination Down Response Message		It should be noted that both modem and router may send a Destination
			Down message to its peer.
			10.14. Destination Down Response Message
	A DLEP participant MUST send a Destination Down Response message to		A DLEP participant MUST send a Destination Down Response message to
	indicate whether a received Destination Down message (Section 9.11)		indicate whether a received Destination Down message (Section 10.13)
	was successfully processed. If successfully processed, the sender of		was successfully processed. If successfully processed, the sender of
	the Response MUST have removed all entries in the information base		the Response MUST have removed all entries in the information base
	that pertain to the referenced destination.		that pertain to the referenced destination.
	To construct a Destination Down Response message, the Message Type		To construct a Destination Down Response message, the Message Type
	value in the message header is set to 12, from Table 1.		value in the message header is set to 12, from Table 1.
	The Destination Down Response message MUST contain one of each of the		The Destination Down Response message MUST contain one of each of the
	following data items:		following data items:
	o MAC Address (Section 10.7)		o MAC Address (Section 11.7)
	The Destination Down Response message MAY contain one of each of the		The Destination Down Response message MAY contain one of each of the
	following data items:		following data items:
	o Status (Section 10.1)		o Status (Section 11.1)
	A receiver of a Destination Down Response message without a Status		A receiver of a Destination Down Response message without a Status
	data item MUST behave as if a Status data item with status code		data item MUST behave as if a Status data item with status code
	'Success' had been received.		'Success' had been received, see Table 3.
	9.13. Destination Update Message		10.15. Destination Update Message
	A DLEP participant SHOULD send the Destination Update message when it		A DLEP modem SHOULD send the Destination Update message when it
	detects some change in the information base for a given destination		detects some change in the information base for a given destination
	(remote node or multicast group). Some examples of changes that		(remote node or multicast group). Some examples of changes that
	would prompt a Destination Update message are:		would prompt a Destination Update message are:
	o Change in link metrics (e.g., Data Rates)		o Change in link metrics (e.g., Data Rates)
	o Layer 3 addressing change		o Layer 3 addressing change
	To construct a Destination Update message, the Message Type value in		To construct a Destination Update message, the Message Type value in
	the message header is set to 13, from Table 1.		the message header is set to 13, from Table 1.
	The Destination Update message MUST contain one of each of the		The Destination Update message MUST contain one of each of the
	following data items:		following data items:
	o MAC Address (Section 10.7)		o MAC Address (Section 11.7)
	The Destination Update message MAY contain one of each of the		The Destination Update message MAY contain one of each of the
	following data items:		following data items:
	o Maximum Data Rate (Receive) (Section 10.12)		o Maximum Data Rate (Receive) (Section 11.12)
	o Maximum Data Rate (Transmit) (Section 10.13)		o Maximum Data Rate (Transmit) (Section 11.13)
	o Current Data Rate (Receive) (Section 10.14)		o Current Data Rate (Receive) (Section 11.14)
	o Current Data Rate (Transmit) (Section 10.15)		o Current Data Rate (Transmit) (Section 11.15)
	o Latency (Section 10.16)		o Latency (Section 11.16)
			The Destination Update message MAY contain one of each of the
			following data items, if the data item is in use by the session:
	o Resources (Receive) (Section 10.17)		o Resources (Receive) (Section 11.17)
	o Resources (Transmit) (Section 10.18)		o Resources (Transmit) (Section 11.18)
	o Relative Link Quality (Receive) (Section 10.19)		o Relative Link Quality (Receive) (Section 11.19)
	o Relative Link Quality (Transmit) (Section 10.20)		o Relative Link Quality (Transmit) (Section 11.20)
			o Maximum Transmission Unit (MTU) (Section 11.21)
	The Destination Update message MAY contain one or more of the		The Destination Update message MAY contain one or more of the
	following data items, with different values:		following data items, with different values:
	o IPv4 Address (Section 10.8)		o IPv4 Address (Section 11.8)
	o IPv6 Address (Section 10.9)
	9.14. Heartbeat Message		o IPv6 Address (Section 11.9)
			o IPv4 Attached Subnet (Section 11.10)
			o IPv6 Attached Subnet (Section 11.11)
			10.16. Heartbeat Message
	While Heartbeat messages are not required by DLEP implementations, it		While Heartbeat messages are not required by DLEP implementations, it
	is strongly RECOMMENDED that Heartbeat messages be used.		is strongly RECOMMENDED that Heartbeat messages be used.
	A Heartbeat message SHOULD be sent by a DLEP participant every N		A Heartbeat message SHOULD be sent by a DLEP participant every N
	seconds, where N is defined in the Heartbeat Interval data item of		seconds, where N is defined in the Heartbeat Interval data item of
	the Session Initialization message (Section 9.3) or Session		the Session Initialization message (Section 10.3) or Session
	Initialization Response message (Section 9.4).		Initialization Response message (Section 10.4).
	Note that implementations setting the Heartbeat Interval to 0		Note that implementations setting the Heartbeat Interval to 0
	effectively sets the interval to an infinite value, turning off		effectively sets the interval to an infinite value, turning off
	Heartbeat messages. Great care MUST be taken when exercising this		Heartbeat messages. Great care MUST be taken when exercising this
	option.		option.
	The message is used by participants to detect when a DLEP session		The message is used by participants to detect when a DLEP session
	partner (either the modem or the router) is no longer communicating.		peer (either the modem or the router) is no longer communicating.
	Participants SHOULD allow two (2) heartbeat intervals to expire with		Participants SHOULD allow two (2) heartbeat intervals to expire with
	no traffic on the router/modem session before initiating DLEP session		no messages from the peer before initiating DLEP session termination
	termination procedures.		procedures.
	To construct a Heartbeat message, the Message Type value in the		To construct a Heartbeat message, the Message Type value in the
	message header is set to 14, from Table 1.		message header is set to 14, from Table 1.
	There are no valid data items for the Heartbeat message.		There are no valid data items for the Heartbeat message.
	9.15. Link Characteristics Request Message		10.17. Link Characteristics Request Message
	The Link Characteristics Request message MAY be sent by the router to		The Link Characteristics Request message MAY be sent by a DLEP router
	request that the modem initiate changes for specific characteristics		to request that the modem initiate changes for specific
	of the link. The request can reference either a real destination		characteristics of the link. The request can reference either a real
	(e.g., a remote node), or a logical destination (e.g., a multicast		destination (e.g., a remote node), or a logical destination (e.g., a
	group) within the network.		multicast group) within the network.
	The Link Characteristics Request message MAY contain either a Current		The Link Characteristics Request message MAY contain either a Current
	Data Rate (CDRR or CDRT) data item to request a different datarate		Data Rate (CDRR or CDRT) data item to request a different datarate
	than what is currently allocated, a Latency data item to request that		than what is currently allocated, a Latency data item to request that
	traffic delay on the link not exceed the specified value, or both. A		traffic delay on the link not exceed the specified value, or both. A
	Link Characteristics Response message (Section 9.16) is required to		Link Characteristics Response message (Section 10.18) is required to
	complete the request. Issuing a Link Characteristics Request with		complete the request. Issuing a Link Characteristics Request with
	ONLY the MAC Address data item is a mechanism a peer MAY use to		ONLY the MAC Address data item is a mechanism a router MAY use to
	request metrics (via the Link Characteristics Response) from its		request metrics (via the Link Characteristics Response) from its
	partner.		modem.
	The sender of a Link Characteristics Request message should be aware		The router sending a Link Characteristics Request message should be
	that a request may take an extended period of time to complete.		aware that a request may take an extended period of time to complete.
	To construct a Link Characteristics Request message, the Message Type		To construct a Link Characteristics Request message, the Message Type
	value in the message header is set to 15, from Table 1.		value in the message header is set to 15, from Table 1.
	The Link Characteristics Request message MUST contain one of each of		The Link Characteristics Request message MUST contain one of each of
	the following data items:		the following data items:
	o MAC Address (Section 10.7)		o MAC Address (Section 11.7)
	The Link Characteristics Request message MAY contain one of each of		The Link Characteristics Request message MAY contain one of each of
	the following data items:		the following data items:
	o Current Data Rate (Receive) (Section 10.14)		o Current Data Rate (Receive) (Section 11.14)
	o Current Data Rate (Transmit) (Section 10.15)		o Current Data Rate (Transmit) (Section 11.15)
	o Latency (Section 10.16)		o Latency (Section 11.16)
	9.16. Link Characteristics Response Message		10.18. Link Characteristics Response Message
	A DLEP participant MUST send a Link Characteristics Response message		A DLEP modem MUST send a Link Characteristics Response message to
	to indicate whether a received Link Characteristics Request message		indicate whether a received Link Characteristics Request message
	(Section 9.15) was successfully processed. The Link Characteristics		(Section 10.17) was successfully processed. The Link Characteristics
	Response message SHOULD contain a complete set of metric data items,		Response message SHOULD contain a complete set of metric data items,
	and MUST contain a full set (i.e. those declared in the Session		and MUST contain a full set (i.e. those declared in the Session
	Initialization Response message (Section 9.4)), if metrics were		Initialization Response message (Section 10.4)), if metrics were
	requested by only including a MAC address data item. It MUST contain		requested by only including a MAC address data item. It MUST contain
	the same metric types as the request. The values in the metric data		the same metric types as the request. The values in the metric data
	items in the Link Characteristics Response message MUST reflect the		items in the Link Characteristics Response message MUST reflect the
	link characteristics after the request has been processed.		link characteristics after the request has been processed.
	If an implementation is not able to alter the characteristics of the		If an implementation is not able to alter the characteristics of the
	link in the manner requested, then a Status data item with status		link in the manner requested, then the message MUST contain a Status
	code 'Request Denied', see Table 3, MUST be added to the message.		data item with status code 'Request Denied', see Table 3.
	To construct a Link Characteristics Response message, the Message		To construct a Link Characteristics Response message, the Message
	Type value in the message header is set to 16, from Table 1.		Type value in the message header is set to 16, from Table 1.
	The Link Characteristics Response message MUST contain one of each of		The Link Characteristics Response message MUST contain one of each of
	the following data items:		the following data items:
	o MAC Address (Section 10.7)		o MAC Address (Section 11.7)
	The Link Characteristics Response message SHOULD contain one of each		The Link Characteristics Response message SHOULD contain one of each
	of the following data items:		of the following data items:
	o Maximum Data Rate (Receive) (Section 10.12)		o Maximum Data Rate (Receive) (Section 11.12)
	o Maximum Data Rate (Transmit) (Section 10.13)		o Maximum Data Rate (Transmit) (Section 11.13)
	o Current Data Rate (Receive) (Section 10.14)
	o Current Data Rate (Transmit) (Section 10.15)		o Current Data Rate (Receive) (Section 11.14)
	o Latency (Section 10.16)		o Current Data Rate (Transmit) (Section 11.15)
			o Latency (Section 11.16)
	The Link Characteristics Response message MAY contain one of each of		The Link Characteristics Response message MAY contain one of each of
	the following data items:		the following data items:
	o Resources (Receive) (Section 10.17)		o Status (Section 11.1)
	o Resources (Transmit) (Section 10.18)		The Link Characteristics Response message MAY contain one of each of
			the following data items, if the data item is in use by the session:
	o Relative Link Quality (Receive) (Section 10.19)		o Resources (Receive) (Section 11.17)
	o Relative Link Quality (Transmit) (Section 10.20)		o Resources (Transmit) (Section 11.18)
	o Status (Section 10.1)		o Relative Link Quality (Receive) (Section 11.19)
	A receiver of a Link Characteristics Response message without a		o Relative Link Quality (Transmit) (Section 11.20)
			o Maximum Transmission Unit (MTU) (Section 11.21)
			A router receiving a Link Characteristics Response message without a
	Status data item MUST behave as if a Status data item with status		Status data item MUST behave as if a Status data item with status
	code 'Success' had been received.		code 'Success', see Table 3, had been received.
	10. DLEP Data Items		11. DLEP Data Items
	Following is the list of core data items that MUST be recognized by a		Following is the list of core data items that MUST be recognized by a
	DLEP compliant implementation. As mentioned before, not all data		DLEP compliant implementation. As mentioned before, not all data
	items need be used during a session, but an implementation MUST		items need be used during a session, but an implementation MUST
	correctly process these data items when correctly associated with a		correctly process these data items when correctly associated with a
	signal or message.		signal or message.
	The core DLEP data items are:		The core DLEP data items are:
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	| Type Code | Description |		| Type Code | Description |
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	| 0 | Reserved |		| 0 | Reserved |
	| 1 | Status (Section 10.1) |		| 1 | Status (Section 11.1) |
	| 2 | IPv4 Connection Point (Section 10.2) |		| 2 | IPv4 Connection Point (Section 11.2) |
	| 3 | IPv6 Connection Point (Section 10.3) |		| 3 | IPv6 Connection Point (Section 11.3) |
	| 4 | Peer Type (Section 10.4) |		| 4 | Peer Type (Section 11.4) |
	| 5 | Heartbeat Interval (Section 10.5) |		| 5 | Heartbeat Interval (Section 11.5) |
	| 6 | Extensions Supported (Section 10.6) |		| 6 | Extensions Supported (Section 11.6) |
	| 7 | MAC Address (Section 10.7) |		| 7 | MAC Address (Section 11.7) |
	| 8 | IPv4 Address (Section 10.8) |		| 8 | IPv4 Address (Section 11.8) |
	| 9 | IPv6 Address (Section 10.9) |		| 9 | IPv6 Address (Section 11.9) |
	| 10 | IPv4 Attached Subnet (Section 10.10) |		| 10 | IPv4 Attached Subnet (Section 11.10) |
	| 11 | IPv6 Attached Subnet (Section 10.11) |		| 11 | IPv6 Attached Subnet (Section 11.11) |
	| 12 | Maximum Data Rate (Receive) MDRR) (Section 10.12) |		| 12 | Maximum Data Rate (Receive) MDRR) (Section 11.12) |
	| 13 | Maximum Data Rate (Transmit) (MDRT) (Section 10.13) |		| 13 | Maximum Data Rate (Transmit) (MDRT) (Section 11.13) |
	| 14 | Current Data Rate (Receive) (CDRR) (Section 10.14) |		| 14 | Current Data Rate (Receive) (CDRR) (Section 11.14) |
	| 15 | Current Data Rate (Transmit) (CDRT) (Section 10.15) |		| 15 | Current Data Rate (Transmit) (CDRT) (Section 11.15) |
	| 16 | Latency (Section 10.16) |		| 16 | Latency (Section 11.16) |
	| 17 | Resources (Receive) (RESR) (Section 10.17) |		| 17 | Resources (Receive) (RESR) (Section 11.17) |
	| 18 | Resources (Transmit) (REST) (Section 10.18) |		| 18 | Resources (Transmit) (REST) (Section 11.18) |
	| 19 | Relative Link Quality (Receive) (RLQR) (Section |		| 19 | Relative Link Quality (Receive) (RLQR) (Section |
	| | 10.19) |		| | 11.19) |
	| 20 | Relative Link Quality (Transmit) (RLQT) (Section |		| 20 | Relative Link Quality (Transmit) (RLQT) (Section |
	| | 10.20) |		| | 11.20) |
	| 21-65407 | Reserved for future extensions |		| 21 | Maximum Transmission Unit (MTU) (Section 11.21) |
			| 22-65407 | Reserved for future extensions |
	| 65408-65534 | Private Use. Available for experiments |		| 65408-65534 | Private Use. Available for experiments |
	| 65535 | Reserved |		| 65535 | Reserved |
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	Table 2: DLEP Data Item types		Table 2: DLEP Data Item types
	10.1. Status		11.1. Status
	The Status data item MAY appear in the Session Initialization		The Status data item MAY appear in the Session Initialization
	Response (Section 9.4), Session Termination (Section 9.7), Session		Response (Section 10.4), Session Termination (Section 10.7), Session
	Termination Response (Section 9.8), Session Update Response		Termination Response (Section 10.8), Session Update Response
	(Section 9.6), Destination Up Response (Section 9.10), Destination		(Section 10.6), Destination Up Response (Section 10.10), Destination
	Down Response (Section 9.12) and Link Characteristics Response		Down Response (Section 10.14) and Link Characteristics Response
	(Section 9.16) messages.		(Section 10.18) messages.
	For the Session Termination message (Section 9.7), the Status data		For the Session Termination message (Section 10.7), the Status data
	item indicates a reason for the termination. For all acknowledgement		item indicates a reason for the termination. For all acknowledgement
	messages, the Status data item is used to indicate the success or		messages, the Status data item is used to indicate the success or
	failure of the previously received message.		failure of the previously received message.
	The status data item includes an optional Text field that can be used		The status data item includes an optional Text field that can be used
	to provide a textual description of the status. The use of the Text		to provide a textual description of the status. The use of the Text
	field is entirely up to the receiving implementation, i.e., it could		field is entirely up to the receiving implementation, i.e., it could
	be output to a log file or discarded. If no Text field is supplied		be output to a log file or discarded. If no Text field is supplied
	with the Status data item, the Length field MUST be set to 1.		with the Status data item, the Length field MUST be set to 1.
	skipping to change at page 36, line 18 ¶		skipping to change at page 39, line 18 ¶
	+-------------+---------+-----------+-------------------------------+		+-------------+---------+-----------+-------------------------------+
	| Success | 0 | Success | The message was processed |		| Success | 0 | Success | The message was processed |
	| | | | successfully. |		| | | | successfully. |
	| Unknown | 1 | Terminate | The message was not |		| Unknown | 1 | Terminate | The message was not |
	| Message | | | recognized by the |		| Message | | | recognized by the |
	| | | | implementation. |		| | | | implementation. |
	| Unexpected | 2 | Terminate | The message was not expected |		| Unexpected | 2 | Terminate | The message was not expected |
	| Message | | | while the device was in the |		| Message | | | while the device was in the |
	| | | | current state, e.g., a |		| | | | current state, e.g., a |
	| | | | Session Initialization |		| | | | Session Initialization |
	| | | | message (Section 9.3) in the |		| | | | message (Section 10.3) in the |
	| | | | In-Session state. |		| | | | In-Session state. |
	| Invalid | 3 | Terminate | One or more data items in the |		| Invalid | 3 | Terminate | One or more data items in the |
	| Data | | | message are invalid, |		| Data | | | message are invalid, |
	| | | | unexpected or incorrectly |		| | | | unexpected or incorrectly |
	| | | | duplicated. |		| | | | duplicated. |
	| Invalid | 4 | Terminate | The destination provided in |		| Invalid | 4 | Terminate | The destination provided in |
	| Destination | | | the message does not match a |		| Destination | | | the message does not match a |
	| | | | previously announced |		| | | | previously announced |
	| | | | destination. For example, in |		| | | | destination. For example, in |
	| | | | the Link Characteristic |		| | | | the Link Characteristic |
	| | | | Response message (Section |		| | | | Response message (Section |
	| | | | 9.16). |		| | | | 10.18). |
	| Timed Out | 5 | Terminate | The session has timed out. |		| Timed Out | 5 | Terminate | The session has timed out. |
	| <Reserved> | 6-90 | Terminate | Reserved for future |		| <Reserved> | 6-90 | Terminate | Reserved for future |
	| | | | extensions. |		| | | | extensions. |
	| <Private | 91-99 | Terminate | Available for experiments. |		| <Private | 91-99 | Terminate | Available for experiments. |
	| Use> | | | |		| Use> | | | |
	| Not | 100 | Continue | The receiver is not |		| Not | 100 | Continue | The receiver is not |
	| Interested | | | interested in this message |		| Interested | | | interested in this message |
	| | | | subject, e.g. a Destination |		| | | | subject, e.g. a Destination |
	| | | | Up Response message (Section |		| | | | Up Response message (Section |
	| | | | 9.10) to indicate no further |		| | | | 10.10) to indicate no further |
	| | | | messages about the |		| | | | messages about the |
	| | | | destination. |		| | | | destination. |
	| Request | 101 | Continue | The receiver refuses to |		| Request | 101 | Continue | The receiver refuses to |
	| Denied | | | complete the request. |		| Denied | | | complete the request. |
	| <Reserved> | 102-243 | Continue | Reserved for future |		| <Reserved> | 102-243 | Continue | Reserved for future |
	| | | | extensions. |		| | | | extensions. |
	| <Private | 244-254 | Continue | Available for experiments. |		| <Private | 244-254 | Continue | Available for experiments. |
	| Use> | | | |		| Use> | | | |
	| <Reserved> | 255 | Terminate | Reserved. |		| <Reserved> | 255 | Terminate | Reserved. |
	+-------------+---------+-----------+-------------------------------+		+-------------+---------+-----------+-------------------------------+
	Table 3: DLEP Status Codes		Table 3: DLEP Status Codes
	A failure mode of 'Terminate' indicates that the session MUST be		A failure mode of 'Terminate' indicates that the session MUST be
	terminated after sending a response containing the status code. A		terminated immediately instead of sending any relevant response
	failure mode of 'Continue' indicates that the session SHOULD continue		message, by sending a Session Termination message (Section 10.7)
	as normal.		containing the status code, and then transitioning to the Session
			Termination state.
	10.2. IPv4 Connection Point		A failure mode of 'Continue' indicates that the session SHOULD
			continue as normal.
			11.2. IPv4 Connection Point
	The IPv4 Connection Point data item MAY appear in the Peer Offer		The IPv4 Connection Point data item MAY appear in the Peer Offer
	signal (Section 9.2).		signal (Section 10.2).
	The IPv4 Connection Point data item indicates the IPv4 address and,		The IPv4 Connection Point data item indicates the IPv4 address and,
	optionally, the TCP port number on the DLEP modem available for		optionally, the TCP port number on the DLEP modem available for
	connections. If provided, the receiver MUST use this information to		connections. If provided, the router MUST use this information to
	perform the TCP connect to the DLEP server.		perform the TCP connect to the modem.
	The IPv4 Connection Point data item contains the following fields:		The IPv4 Connection Point data item contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Flags | IPv4 Address... :		| Flags | IPv4 Address... :
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 37, line 44 ¶		skipping to change at page 40, line 48 ¶
	Length: 5 (or 7 if TCP Port included)		Length: 5 (or 7 if TCP Port included)
	Flags: Flags field, defined below.		Flags: Flags field, defined below.
	IPv4 Address: The IPv4 address listening on the DLEP modem.		IPv4 Address: The IPv4 address listening on the DLEP modem.
	TCP Port Number: TCP Port number on the DLEP modem.		TCP Port Number: TCP Port number on the DLEP modem.
	If the Length field is 7, the port number specified MUST be used to		If the Length field is 7, the port number specified MUST be used to
	establish the TCP session. If the TCP Port Number is omitted, i.e.		establish the TCP session. If the TCP Port Number is omitted, i.e.
	the Length field is 5, the receiver MUST use the DLEP well-known port		the Length field is 5, the router MUST use the DLEP well-known port
	number (Section 12.7) to establish the TCP connection.		number (Section 13.6) to establish the TCP connection.
	The Flags field is defined as:		The Flags field is defined as:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	| MBZ |T|		| Reserved |T|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	T: Use TLS flag, indicating whether the TCP connection requires the		T: Use TLS flag, indicating whether the TCP connection requires the
	use of TLS (1), or not (0).		use of TLS (1), or not (0).
	MBZ: MUST be zero. Reserved for future use.		Reserved: MUST be zero. Reserved for future use.
	10.3. IPv6 Connection Point		11.3. IPv6 Connection Point
	The IPv6 Connection Point data item MAY appear in the Peer Offer		The IPv6 Connection Point data item MAY appear in the Peer Offer
	signal (Section 9.2).		signal (Section 10.2).
	The IPv6 Connection Point data item indicates the IPv6 address and,		The IPv6 Connection Point data item indicates the IPv6 address and,
	optionally, the TCP port number on the DLEP modem available for		optionally, the TCP port number on the DLEP modem available for
	connections. If provided, the receiver MUST use this information to		connections. If provided, the router MUST use this information to
	perform the TCP connect to the DLEP server.		perform the TCP connect to the modem.
	The IPv6 Connection Point data item contains the following fields:		The IPv6 Connection Point data item contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Flags | IPv6 Address :		| Flags | IPv6 Address :
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 38, line 49 ¶		skipping to change at page 42, line 7 ¶
	Length: 17 (or 19 if TCP Port included)		Length: 17 (or 19 if TCP Port included)
	Flags: Flags field, defined below.		Flags: Flags field, defined below.
	IPv6 Address: The IPv6 address listening on the DLEP modem.		IPv6 Address: The IPv6 address listening on the DLEP modem.
	TCP Port Number: TCP Port number on the DLEP modem.		TCP Port Number: TCP Port number on the DLEP modem.
	If the Length field is 19, the port number specified MUST be used to		If the Length field is 19, the port number specified MUST be used to
	establish the TCP session. If the TCP Port Number is omitted, i.e.		establish the TCP session. If the TCP Port Number is omitted, i.e.
	the Length field is 17, the receiver MUST use the DLEP well-known		the Length field is 17, the router MUST use the DLEP well-known port
	port number (Section 12.7) to establish the TCP connection.		number (Section 13.6) to establish the TCP connection.
	The Flags field is defined as:		The Flags field is defined as:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	| MBZ |T|		| Reserved |T|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	T: Use TLS flag, indicating whether the TCP connection requires the		T: Use TLS flag, indicating whether the TCP connection requires the
	use of TLS (1), or not (0).		use of TLS (1), or not (0).
	MBZ: MUST be zero. Reserved for future use.		Reserved: MUST be zero. Reserved for future use.
	10.4. Peer Type		11.4. Peer Type
	The Peer Type data item MAY appear in the Peer Discovery		The Peer Type data item MAY appear in the Peer Discovery
	(Section 9.1) and Peer Offer (Section 9.2) signals, and the Session		(Section 10.1) and Peer Offer (Section 10.2) signals, and the Session
	Initialization (Section 9.3) and Session Initialization Response		Initialization (Section 10.3) and Session Initialization Response
	(Section 9.4) messages.		(Section 10.4) messages.
	The Peer Type data item is used by the router and modem to give		The Peer Type data item is used by the router and modem to give
	additional information as to its type. The peer type is a string and		additional information as to its type. The peer type is a string and
	is envisioned to be used for informational purposes (e.g., as output		is envisioned to be used for informational purposes (e.g., as output
	in a display command).		in a display command).
	The Peer Type data item contains the following fields:		The Peer Type data item contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	skipping to change at page 40, line 5 ¶		skipping to change at page 43, line 10 ¶
	Peer Type: UTF-8 encoded string. For example, a satellite modem		Peer Type: UTF-8 encoded string. For example, a satellite modem
	might set this variable to "Satellite terminal". Since this data		might set this variable to "Satellite terminal". Since this data
	item is intended to provide additional information for display		item is intended to provide additional information for display
	commands, sending implementations SHOULD limit the data to		commands, sending implementations SHOULD limit the data to
	printable characters, and receiving implementations SHOULD check		printable characters, and receiving implementations SHOULD check
	the data for printable characters.		the data for printable characters.
	An implementation MUST NOT assume the Peer Type field is NUL-		An implementation MUST NOT assume the Peer Type field is NUL-
	terminated.		terminated.
	10.5. Heartbeat Interval		11.5. Heartbeat Interval
	The Heartbeat Interval data item MUST appear in both the Session		The Heartbeat Interval data item MUST appear in both the Session
	Initialization (Section 9.3) and Session Initialization Response		Initialization (Section 10.3) and Session Initialization Response
	(Section 9.4) messages to indicate the Heartbeat timeout window to be		(Section 10.4) messages to indicate the Heartbeat timeout window to
	used by the sender.		be used by the sender.
	The Interval is used to specify a period (in seconds) for Heartbeat		The Interval is used to specify a period (in seconds) for Heartbeat
	messages (Section 9.14). By specifying an Interval value of 0,		messages (Section 10.16). By specifying an Interval value of 0,
	implementations MAY indicate the desire to disable Heartbeat messages		implementations MAY indicate the desire to disable Heartbeat messages
	entirely (i.e., the Interval is set to an infinite value). However,		entirely (i.e., the Interval is set to an infinite value). However,
	it is RECOMMENDED that implementations use non-0 timer values.		it is RECOMMENDED that implementations use non-0 timer values.
	The Heartbeat Interval data item contains the following fields:		The Heartbeat Interval data item contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	skipping to change at page 40, line 35 ¶		skipping to change at page 43, line 40 ¶
	| Interval |		| Interval |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Data Item Type: 5		Data Item Type: 5
	Length: 2		Length: 2
	Interval: 0 = Do not use heartbeats on this DLEP session. Non-zero		Interval: 0 = Do not use heartbeats on this DLEP session. Non-zero
	= Interval, in seconds, for heartbeat messages.		= Interval, in seconds, for heartbeat messages.
	10.6. Extensions Supported		11.6. Extensions Supported
	The Extensions Supported data item MAY be used in both the Session		The Extensions Supported data item MAY be used in both the Session
	Initialization (Section 9.3) and Session Initialization Response		Initialization (Section 10.3) and Session Initialization Response
	(Section 9.4) messages.		(Section 10.4) messages.
	The Extensions Supported data item is used by the router and modem to		The Extensions Supported data item is used by the router and modem to
	negotiate additional optional functionality they are willing to		negotiate additional optional functionality they are willing to
	support. The Extensions List is a concatenation of the types of each		support. The Extensions List is a concatenation of the types of each
	supported extension, found in the IANA DLEP Extensions repository.		supported extension, found in the IANA DLEP Extensions repository.
	Each Extension Type definition includes which additional signals and		Each Extension Type definition includes which additional signals and
	data-items are supported.		data-items are supported.
	The Extensions Supported data item contains the following fields:		The Extensions Supported data item contains the following fields:
	skipping to change at page 41, line 21 ¶		skipping to change at page 44, line 23 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Data Item Type: 6		Data Item Type: 6
	Length: Length of the extensions list in octets. This is twice (2x)		Length: Length of the extensions list in octets. This is twice (2x)
	the number of extensions.		the number of extensions.
	Extension List: A list of extensions supported, identified by their		Extension List: A list of extensions supported, identified by their
	2-octet value as listed in the extensions registry.		2-octet value as listed in the extensions registry.
	10.7. MAC Address		11.7. MAC Address
	The MAC address data item MUST appear in all destination-oriented		The MAC address data item MUST appear in all destination-oriented
	messages (i.e., Destination Up (Section 9.9), Destination Up Response		messages (i.e., Destination Up (Section 10.9), Destination Up
	(Section 9.10), Destination Down (Section 9.11), Destination Down		Response (Section 10.10), Destination Down (Section 10.13),
	Response (Section 9.12), Destination Update (Section 9.13), Link		Destination Down Response (Section 10.14), Destination Update
	Characteristics Request (Section 9.15), and Link Characteristics		(Section 10.15), Link Characteristics Request (Section 10.17), and
	Response (Section 9.16)).		Link Characteristics Response (Section 10.18)).
	The MAC Address data item contains the address of the destination on		The MAC Address data item contains the address of the destination on
	the remote node. The MAC address MAY be either a physical or a		the remote node. The MAC address MAY be either a physical or a
	virtual destination, and MAY be expressed in EUI-48 or EUI-64 format.		virtual destination, and MAY be expressed in EUI-48 or EUI-64 format.
	Examples of a virtual destination would be a multicast MAC address,		Examples of a virtual destination would be a multicast MAC address,
	or the broadcast MAC (FF:FF:FF:FF:FF:FF).		or the broadcast MAC (FF:FF:FF:FF:FF:FF).
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 41, line 51 ¶		skipping to change at page 45, line 4 ¶
	| MAC Address :		| MAC Address :
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	: MAC Address :		: MAC Address :
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	: MAC Address : (if EUI-64 used) |		: MAC Address : (if EUI-64 used) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Data Item Type: 7		Data Item Type: 7
	Length: 6 for EUI-48 format, or 8 for EUI-64 format		Length: 6 for EUI-48 format, or 8 for EUI-64 format
	MAC Address: MAC Address of the destination.		MAC Address: MAC Address of the destination.
	10.8. IPv4 Address		11.8. IPv4 Address
	The IPv4 Address data item MAY appear in the Session Update		The IPv4 Address data item MAY appear in the Session Update
	(Section 9.5), Destination Up (Section 9.9) and Destination Update		(Section 10.5), Destination Up (Section 10.9) and Destination Update
	(Section 9.13) messages.		(Section 10.15) messages.
	When included in Destination messages, this data item contains the		When included in Destination messages, this data item contains the
	IPv4 address of the destination. When included in the Session Update		IPv4 address of the destination. When included in the Session Update
	message, this data item contains the IPv4 address of the peer. In		message, this data item contains the IPv4 address of the peer. In
	either case, the data item also contains an indication of whether		either case, the data item also contains an indication of whether
	this is a new or existing address, or is a deletion of a previously		this is a new or existing address, or is a deletion of a previously
	known address.		known address.
	The IPv4 Address data item contains the following fields:		The IPv4 Address data item contains the following fields:
	skipping to change at page 42, line 42 ¶		skipping to change at page 45, line 43 ¶
	Length: 5		Length: 5
	Flags: Flags field, defined below.		Flags: Flags field, defined below.
	IPv4 Address: The IPv4 address of the destination or peer.		IPv4 Address: The IPv4 address of the destination or peer.
	The Flags field is defined as:		The Flags field is defined as:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	| MBZ |A|		| Reserved |A|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	A: Add/Drop flag, indicating whether this is a new or existing		A: Add/Drop flag, indicating whether this is a new or existing
	address (1), or a withdrawal of an address (0).		address (1), or a withdrawal of an address (0).
	MBZ: MUST be zero. Reserved for future use.		Reserved: MUST be zero. Reserved for future use.
	10.9. IPv6 Address		11.9. IPv6 Address
	The IPv6 Address data item MAY appear in the Session Update		The IPv6 Address data item MAY appear in the Session Update
	(Section 9.5), Destination Up (Section 9.9) and Destination Update		(Section 10.5), Destination Up (Section 10.9) and Destination Update
	(Section 9.13) messages. When included in Destination messages, this		(Section 10.15) messages. When included in Destination messages,
	data item contains the IPv6 address of the destination. When		this data item contains the IPv6 address of the destination. When
	included in the Session Update message, this data item contains the		included in the Session Update message, this data item contains the
	IPv6 address of the peer. In either case, the data item also		IPv6 address of the peer. In either case, the data item also
	contains an indication of whether this is a new or existing address,		contains an indication of whether this is a new or existing address,
	or is a deletion of a previously known address.		or is a deletion of a previously known address.
	The IPv6 Address data item contains the following fields:		The IPv6 Address data item contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 43, line 46 ¶		skipping to change at page 46, line 46 ¶
	Length: 17		Length: 17
	Flags: Flags field, defined below.		Flags: Flags field, defined below.
	IPv6 Address: IPv6 Address of the destination or peer.		IPv6 Address: IPv6 Address of the destination or peer.
	The Flags field is defined as:		The Flags field is defined as:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	| MBZ |A|		| Reserved |A|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	A: Add/Drop flag, indicating whether this is a new or existing		A: Add/Drop flag, indicating whether this is a new or existing
	address (1), or a withdrawal of an address (0).		address (1), or a withdrawal of an address (0).
	MBZ: MUST be zero. Reserved for future use.		Reserved: MUST be zero. Reserved for future use.
	10.10. IPv4 Attached Subnet		11.10. IPv4 Attached Subnet
	The DLEP IPv4 Attached Subnet allows a device to declare that it has		The DLEP IPv4 Attached Subnet allows a device to declare that it has
	an IPv4 subnet (e.g., a stub network) attached, that it has become		an IPv4 subnet (e.g., a stub network) attached, that it has become
	aware of an IPv4 subnet being present at a remote destination, or		aware of an IPv4 subnet being present at a remote destination, or
	that it has become aware of the loss of a subnet at the remote		that it has become aware of the loss of a subnet at the remote
	destination. The IPv4 Attached Subnet data item MAY appear in the		destination. The IPv4 Attached Subnet data item MAY appear in the
	Destination Up (Section 9.9) message.		Destination Up (Section 10.9) and Destination Update (Section 10.15)
			messages.
	The DLEP IPv4 Attached Subnet data item contains the following		The DLEP IPv4 Attached Subnet data item contains the following
	fields:		fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Flags | IPv4 Attached Subnet :		| Flags | IPv4 Attached Subnet :
	skipping to change at page 44, line 43 ¶		skipping to change at page 47, line 44 ¶
	IPv4 Subnet: The IPv4 subnet reachable at the destination.		IPv4 Subnet: The IPv4 subnet reachable at the destination.
	Prefix Length: Length of the prefix (1-32) for the IPv4 subnet. A		Prefix Length: Length of the prefix (1-32) for the IPv4 subnet. A
	prefix length outside the specified range MUST be considered as		prefix length outside the specified range MUST be considered as
	invalid.		invalid.
	The Flags field is defined as:		The Flags field is defined as:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	| MBZ |A|		| Reserved |A|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	A: Add/Drop flag, indicating whether this is a new or existing subnet		A: Add/Drop flag, indicating whether this is a new or existing subnet
	address (1), or a withdrawal of a subnet address (0).		address (1), or a withdrawal of a subnet address (0).
	MBZ: MUST be zero. Reserved for future use.		Reserved: MUST be zero. Reserved for future use.
	10.11. IPv6 Attached Subnet		11.11. IPv6 Attached Subnet
	The DLEP IPv6 Attached Subnet allows a device to declare that it has		The DLEP IPv6 Attached Subnet allows a device to declare that it has
	an IPv6 subnet (e.g., a stub network) attached, or that it has become		an IPv6 subnet (e.g., a stub network) attached, or that it has become
	aware of an IPv6 subnet being present at a remote destination. The		aware of an IPv6 subnet being present at a remote destination. The
	IPv6 Attached Subnet data item MAY appear in the Destination Up		IPv6 Attached Subnet data item MAY appear in the Destination Up
	(Section 9.9) message. As in the case of the IPv4 attached Subnet		(Section 10.9) and Destination Update (Section 10.15) messages.
	data item above, once an IPv6 attached subnet has been declared, it
	SHALL NOT be withdrawn without withdrawing the destination (via the
	Destination Down message (Section 9.11)) and re-issuing the
	Destination Up message.
	The DLEP IPv6 Attached Subnet data item contains the following		The DLEP IPv6 Attached Subnet data item contains the following
	fields:		fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Flags | IPv6 Attached Subnet :		| Flags | IPv6 Attached Subnet :
	skipping to change at page 46, line 7 ¶		skipping to change at page 48, line 48 ¶
	IPv6 Attached Subnet: The IPv6 subnet reachable at the destination.		IPv6 Attached Subnet: The IPv6 subnet reachable at the destination.
	Prefix Length: Length of the prefix (1-128) for the IPv6 subnet. A		Prefix Length: Length of the prefix (1-128) for the IPv6 subnet. A
	prefix length outside the specified range MUST be considered as		prefix length outside the specified range MUST be considered as
	invalid.		invalid.
	The Flags field is defined as:		The Flags field is defined as:
	0 1 2 3 4 5 6 7		0 1 2 3 4 5 6 7
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	| MBZ |A|		| Reserved |A|
	+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+
	A: Add/Drop flag, indicating whether this is a new or existing subnet		A: Add/Drop flag, indicating whether this is a new or existing subnet
	address (1), or a withdrawal of a subnet address (0).		address (1), or a withdrawal of a subnet address (0).
	MBZ: MUST be zero. Reserved for future use.		Reserved: MUST be zero. Reserved for future use.
	10.12. Maximum Data Rate (Receive)		11.12. Maximum Data Rate (Receive)
	The Maximum Data Rate (Receive) (MDRR) data item MUST appear in the		The Maximum Data Rate (Receive) (MDRR) data item MUST appear in the
	Session Initialization Response message (Section 9.4), and MAY appear		Session Initialization Response message (Section 10.4), and MAY
	in the Session Update (Section 9.5), Destination Up (Section 9.9),		appear in the Session Update (Section 10.5), Destination Up
	Destination Update (Section 9.13) and Link Characteristics Response		(Section 10.9), Destination Update (Section 10.15) and Link
	(Section 9.16) messages to indicate the maximum theoretical data		Characteristics Response (Section 10.18) messages to indicate the
	rate, in bits per second, that can be achieved while receiving data		maximum theoretical data rate, in bits per second, that can be
	on the link.		achieved while receiving data on the link.
	The Maximum Data Rate (Receive) data item contains the following		The Maximum Data Rate (Receive) data item contains the following
	fields:		fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| MDRR (bps) :		| MDRR (bps) :
	skipping to change at page 46, line 46 ¶		skipping to change at page 49, line 38 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Data Item Type: 12		Data Item Type: 12
	Length: 8		Length: 8
	Maximum Data Rate (Receive): A 64-bit unsigned integer, representing		Maximum Data Rate (Receive): A 64-bit unsigned integer, representing
	the maximum theoretical data rate, in bits per second (bps), that		the maximum theoretical data rate, in bits per second (bps), that
	can be achieved while receiving on the link.		can be achieved while receiving on the link.
	10.13. Maximum Data Rate (Transmit)		11.13. Maximum Data Rate (Transmit)
	The Maximum Data Rate (Transmit) (MDRT) data item MUST appear in the		The Maximum Data Rate (Transmit) (MDRT) data item MUST appear in the
	Session Initialization Response message (Section 9.4), and MAY appear		Session Initialization Response message (Section 10.4), and MAY
	in the Session Update (Section 9.5), Destination Up (Section 9.9),		appear in the Session Update (Section 10.5), Destination Up
	Destination Update (Section 9.13) and Link Characteristics Response		(Section 10.9), Destination Update (Section 10.15) and Link
	(Section 9.16) messages to indicate the maximum theoretical data		Characteristics Response (Section 10.18) messages to indicate the
	rate, in bits per second, that can be achieved while transmitting		maximum theoretical data rate, in bits per second, that can be
	data on the link.		achieved while transmitting data on the link.
	The Maximum Data Rate (Transmit) data item contains the following		The Maximum Data Rate (Transmit) data item contains the following
	fields:		fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| MDRT (bps) :		| MDRT (bps) :
	skipping to change at page 47, line 28 ¶		skipping to change at page 50, line 23 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Data Item Type: 13		Data Item Type: 13
	Length: 8		Length: 8
	Maximum Data Rate (Transmit): A 64-bit unsigned integer,		Maximum Data Rate (Transmit): A 64-bit unsigned integer,
	representing the maximum theoretical data rate, in bits per second		representing the maximum theoretical data rate, in bits per second
	(bps), that can be achieved while transmitting on the link.		(bps), that can be achieved while transmitting on the link.
	10.14. Current Data Rate (Receive)		11.14. Current Data Rate (Receive)
	The Current Data Rate (Receive) (CDRR) data item MUST appear in the		The Current Data Rate (Receive) (CDRR) data item MUST appear in the
	Session Initialization Response message (Section 9.4), and MAY appear		Session Initialization Response message (Section 10.4), and MAY
	in the Session Update (Section 9.5), Destination Up (Section 9.9),		appear in the Session Update (Section 10.5), Destination Up
	Destination Update (Section 9.13) and Link Characteristics Response		(Section 10.9), Destination Update (Section 10.15) and Link
	(Section 9.16) messages to indicate the rate at which the link is		Characteristics Response (Section 10.18) messages to indicate the
	currently operating for receiving traffic.		rate at which the link is currently operating for receiving traffic.
	When used in the Link Characteristics Request message (Section 9.15),		When used in the Link Characteristics Request message
	CDRR represents the desired receive rate, in bits per second, on the		(Section 10.17), CDRR represents the desired receive rate, in bits
	link.		per second, on the link.
	The Current Data Rate (Receive) data item contains the following		The Current Data Rate (Receive) data item contains the following
	fields:		fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| CDRR (bps) :		| CDRR (bps) :
	skipping to change at page 48, line 18 ¶		skipping to change at page 51, line 4 ¶
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| CDRR (bps) :		| CDRR (bps) :
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	: CDRR (bps) |		: CDRR (bps) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Data Item Type: 14		Data Item Type: 14
	Length: 8		Length: 8
	Current Data Rate (Receive): A 64-bit unsigned integer, representing		Current Data Rate (Receive): A 64-bit unsigned integer, representing
	the current data rate, in bits per second, that can currently be		the current data rate, in bits per second, that can currently be
	achieved while receiving traffic on the link.		achieved while receiving traffic on the link.
	If there is no distinction between current and maximum receive data		If there is no distinction between current and maximum receive data
	rates, current data rate receive MUST be set equal to the maximum		rates, current data rate receive MUST be set equal to the maximum
	data rate receive.		data rate receive.
	10.15. Current Data Rate (Transmit)		11.15. Current Data Rate (Transmit)
	The Current Data Rate Transmit (CDRT) data item MUST appear in the		The Current Data Rate Transmit (CDRT) data item MUST appear in the
	Session Initialization Response message (Section 9.4), and MAY appear		Session Initialization Response message (Section 10.4), and MAY
	in the Session Update (Section 9.5), Destination Up (Section 9.9),		appear in the Session Update (Section 10.5), Destination Up
	Destination Update (Section 9.13), and Link Characteristics Response		(Section 10.9), Destination Update (Section 10.15), and Link
	(Section 9.16) messages to indicate the rate at which the link is		Characteristics Response (Section 10.18) messages to indicate the
	currently operating for transmitting traffic.		rate at which the link is currently operating for transmitting
			traffic.
	When used in the Link Characteristics Request message (Section 9.15),		When used in the Link Characteristics Request message
	CDRT represents the desired transmit rate, in bits per second, on the		(Section 10.17), CDRT represents the desired transmit rate, in bits
	link.		per second, on the link.
	The Current Data Rate (Transmit) data item contains the following		The Current Data Rate (Transmit) data item contains the following
	fields:		fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| CDRT (bps) :		| CDRT (bps) :
	skipping to change at page 49, line 4 ¶		skipping to change at page 51, line 38 ¶
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| CDRT (bps) :		| CDRT (bps) :
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	: CDRT (bps) |		: CDRT (bps) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Data Item Type: 15		Data Item Type: 15
	Length: 8		Length: 8
	Current Data Rate (Transmit): A 64-bit unsigned integer,		Current Data Rate (Transmit): A 64-bit unsigned integer,
	representing the current data rate, in bits per second, that can		representing the current data rate, in bits per second, that can
	currently be achieved while transmitting traffic on the link.		currently be achieved while transmitting traffic on the link.
	If there is no distinction between current and maximum transmit data		If there is no distinction between current and maximum transmit data
	rates, current data rate transmit MUST be set equal to the maximum		rates, current data rate transmit MUST be set equal to the maximum
	data rate transmit.		data rate transmit.
	10.16. Latency		11.16. Latency
	The Latency data item MUST appear in the Session Initialization		The Latency data item MUST appear in the Session Initialization
	Response message (Section 9.4), and MAY appear in the Session Update		Response message (Section 10.4), and MAY appear in the Session Update
	(Section 9.5), Destination Up (Section 9.9), Destination Update		(Section 10.5), Destination Up (Section 10.9), Destination Update
	(Section 9.13), and Link Characteristics Response (Section 9.16)		(Section 10.15), and Link Characteristics Response (Section 10.18)
	messages to indicate the amount of latency, in microseconds, on the		messages to indicate the amount of latency, in microseconds, on the
	link.		link.
	When used in the Link Characteristics Request message (Section 9.15),		When used in the Link Characteristics Request message
	Latency represents the maximum latency desired on the link.		(Section 10.17), Latency represents the maximum latency desired on
			the link.
	The Latency value is reported as delay. The calculation of latency		The Latency value is reported as delay. The calculation of latency
	is implementation dependent. For example, the latency may be a		is implementation dependent. For example, the latency may be a
	running average calculated from the internal queuing.		running average calculated from the internal queuing.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 50, line 5 ¶		skipping to change at page 52, line 40 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Data Item Type: 16		Data Item Type: 16
	Length: 8		Length: 8
	Latency: A 64-bit unsigned integer, representing the transmission		Latency: A 64-bit unsigned integer, representing the transmission
	delay, in microseconds, that a packet encounters as it is		delay, in microseconds, that a packet encounters as it is
	transmitted over the link.		transmitted over the link.
	10.17. Resources (Receive)		11.17. Resources (Receive)
	The Resources (Receive) (RESR) data item MAY appear in the Session		The Resources (Receive) (RESR) data item MAY appear in the Session
	Initialization Response message (Section 9.4), Session Update		Initialization Response message (Section 10.4), Session Update
	(Section 9.5), Destination Up (Section 9.9), Destination Update		(Section 10.5), Destination Up (Section 10.9), Destination Update
	(Section 9.13) and Link Characteristics Response (Section 9.16)		(Section 10.15) and Link Characteristics Response (Section 10.18)
	messages to indicate the amount of resources for reception (with 0		messages to indicate the amount of resources for reception (with 0
	meaning 'no resources available', and 100 meaning 'all resources		meaning 'no resources available', and 100 meaning 'all resources
	available') at the destination. The list of resources that might be		available') at the destination. The list of resources that might be
	considered is beyond the scope of this document, and is left to		considered is beyond the scope of this document, and is left to
	implementations to decide.		implementations to decide.
	The Resources (Receive) data item contains the following fields:		The Resources (Receive) data item contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	skipping to change at page 50, line 38 ¶		skipping to change at page 53, line 24 ¶
	Length: 1		Length: 1
	Resources (Receive): An 8-bit integer percentage, 0-100,		Resources (Receive): An 8-bit integer percentage, 0-100,
	representing the amount of resources allocated to receiving data.		representing the amount of resources allocated to receiving data.
	Any value greater than 100 MUST be considered as invalid.		Any value greater than 100 MUST be considered as invalid.
	If a device cannot calculate RESR, this data item SHOULD NOT be		If a device cannot calculate RESR, this data item SHOULD NOT be
	issued.		issued.
	10.18. Resources (Transmit)		11.18. Resources (Transmit)
	The Resources (Transmit) (REST) data item MAY appear in the Session		The Resources (Transmit) (REST) data item MAY appear in the Session
	Initialization Response message (Section 9.4), Session Update		Initialization Response message (Section 10.4), Session Update
	(Section 9.5), Destination Up (Section 9.9), Destination Update		(Section 10.5), Destination Up (Section 10.9), Destination Update
	(Section 9.13) and Link Characteristics Response (Section 9.16)		(Section 10.15) and Link Characteristics Response (Section 10.18)
	messages to indicate the amount of resources for transmission (with 0		messages to indicate the amount of resources for transmission (with 0
	meaning 'no resources available', and 100 meaning 'all resources		meaning 'no resources available', and 100 meaning 'all resources
	available') at the destination. The list of resources that might be		available') at the destination. The list of resources that might be
	considered is beyond the scope of this document, and is left to		considered is beyond the scope of this document, and is left to
	implementations to decide.		implementations to decide.
	The Resources (Transmit) data item contains the following fields:		The Resources (Transmit) data item contains the following fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	skipping to change at page 51, line 24 ¶		skipping to change at page 54, line 8 ¶
	Length: 1		Length: 1
	Resources (Transmit): An 8-bit integer percentage, 0-100,		Resources (Transmit): An 8-bit integer percentage, 0-100,
	representing the amount of resources allocated to transmitting		representing the amount of resources allocated to transmitting
	data. Any value greater than 100 MUST be considered as invalid.		data. Any value greater than 100 MUST be considered as invalid.
	If a device cannot calculate REST, this data item SHOULD NOT be		If a device cannot calculate REST, this data item SHOULD NOT be
	issued.		issued.
	10.19. Relative Link Quality (Receive)		11.19. Relative Link Quality (Receive)
	The Relative Link Quality (Receive) (RLQR) data item MAY appear in		The Relative Link Quality (Receive) (RLQR) data item MAY appear in
	the Session Initialization Response message (Section 9.4), Session		the Session Initialization Response message (Section 10.4), Session
	Update (Section 9.5), Destination Up (Section 9.9), Destination		Update (Section 10.5), Destination Up (Section 10.9), Destination
	Update (Section 9.13) and Link Characteristics Response		Update (Section 10.15) and Link Characteristics Response
	(Section 9.16) messages to indicate the quality of the link for		(Section 10.18) messages to indicate the quality of the link for
	receiving data.		receiving data.
	The Relative Link Quality (Receive) data item contains the following		The Relative Link Quality (Receive) data item contains the following
	fields:		fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 52, line 8 ¶		skipping to change at page 54, line 40 ¶
	Length: 1		Length: 1
	Relative Link Quality (Receive): A non-dimensional 8-bit integer,		Relative Link Quality (Receive): A non-dimensional 8-bit integer,
	0-100, representing relative link quality. A value of 100		0-100, representing relative link quality. A value of 100
	represents a link of the highest quality. Any value greater than		represents a link of the highest quality. Any value greater than
	100 MUST be considered as invalid.		100 MUST be considered as invalid.
	If a device cannot calculate the RLQR, this data item SHOULD NOT be		If a device cannot calculate the RLQR, this data item SHOULD NOT be
	issued.		issued.
	10.20. Relative Link Quality (Transmit)		11.20. Relative Link Quality (Transmit)
	The Relative Link Quality (Transmit) (RLQT) data item MAY appear in		The Relative Link Quality (Transmit) (RLQT) data item MAY appear in
	the Session Initialization Response message (Section 9.4), Session		the Session Initialization Response message (Section 10.4), Session
	Update (Section 9.5), Destination Up (Section 9.9), Destination		Update (Section 10.5), Destination Up (Section 10.9), Destination
	Update (Section 9.13) and Link Characteristics Response		Update (Section 10.15) and Link Characteristics Response
	(Section 9.16) messages to indicate the quality of the link for		(Section 10.18) messages to indicate the quality of the link for
	transmitting data.		transmitting data.
	The Relative Link Quality (Transmit) data item contains the following		The Relative Link Quality (Transmit) data item contains the following
	fields:		fields:
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Data Item Type | Length |		| Data Item Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 52, line 40 ¶		skipping to change at page 55, line 25 ¶
	Length: 1		Length: 1
	Relative Link Quality (Transmit): A non-dimensional 8-bit integer,		Relative Link Quality (Transmit): A non-dimensional 8-bit integer,
	0-100, representing relative link quality. A value of 100		0-100, representing relative link quality. A value of 100
	represents a link of the highest quality. Any value greater than		represents a link of the highest quality. Any value greater than
	100 MUST be considered as invalid.		100 MUST be considered as invalid.
	If a device cannot calculate the RLQT, this data item SHOULD NOT be		If a device cannot calculate the RLQT, this data item SHOULD NOT be
	issued.		issued.
	11. Security Considerations		11.21. Maximum Transmission Unit (MTU)
			The Maximum Transmission Unit (MTU) data item MAY appear in the
			Session Initialization Response message (Section 10.4), Session
			Update (Section 10.5), Destination Up (Section 10.9), Destination
			Update (Section 10.15) and Link Characteristics Response
			(Section 10.18) messages to indicate the maximum size, in octets, of
			an IP packet that can be transmitted without fragmentation, including
			headers, but excluding any lower layer headers.
			The Maximum Transmission Unit (MTU) data item contains the following
			fields:
			0 1 2 3
			0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| Data Item Type | Length |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			| MTU |
			+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
			Data Item Type: 21
			Length: 2
			Maximum Transmission Unit (MTU): The maximum size, in octets, of an
			IP packet that can be transmitted without fragmentation, including
			headers, but excluding any lower layer headers.
			If a device cannot calculate the MTU, this data item SHOULD NOT be
			issued.
			12. Security Considerations
	The potential security concerns when using DLEP are:		The potential security concerns when using DLEP are:
	1. DLEP peers may be 'spoofed' by an attacker, either at DLEP		1. An attacker might pretend to be a DLEP peer, either at DLEP
	session initialization, or by injection of messages once a		session initialization, or by injection of messages once a
	session has been established, and/or		session has been established, and/or
	2. DLEP data items could be altered by an attacker, causing the		2. DLEP data items could be altered by an attacker, causing the
	receiving peer to inappropriately alter its information base		receiving implementation to inappropriately alter its information
	concerning network status.		base concerning network status.
	If the modem and router are separated by more than a single hop,		Since DLEP is restricted to operation over a single (possibly
	session messages could be altered in order to subvert the behaviour		logical) hop at layer 2, implementations requiring authentication
	of either or both DLEP participants. Under these circumstances, DLEP		and/or encryption of traffic MUST take steps to secure the Layer 2
	participants MUST implement TLS [RFC5246].		link.
	To avoid potential denial of service attack, it is RECOMMENDED that		To avoid potential denial of service attack, it is RECOMMENDED that
	implementations using the Peer Discovery mechanism maintain an		implementations using the Peer Discovery mechanism maintain an
	information base of peers that persistently fail Session		information base of hosts that persistently fail Session
	Initialization having provided an acceptable Discovery signal, and		Initialization having provided an acceptable Discovery signal, and
	ignore Peer Discovery signals from such peers.		ignore Peer Discovery signals from such hosts.
	This specification does not address security of the data plane, as it		This specification does not address security of the data plane, as it
	(the data plane) is not affected, and standard security procedures		(the data plane) is not affected, and standard security procedures
	can be employed.		can be employed.
	12. IANA Considerations		13. IANA Considerations
	This section specifies requests to IANA.		This section specifies requests to IANA.
	12.1. Registrations		13.1. Registrations
	This specification defines:		This specification defines:
	o A new repository for DLEP signals and messages, with sixteen (16)		o A new repository for DLEP signals and messages, with eighteen (18)
	values currently assigned.		values currently assigned.
	o Reservation of a Private Use numbering space for experimental DLEP		o Reservation of a Private Use numbering space within the above
	signals and messages.		repository for experimental DLEP signals and messages.
	o A new repository for DLEP data items, with twenty-four (24) values		o A new repository for DLEP data items, with twenty-one (21) values
	currently assigned.		currently assigned.
	o Reservation of a Private Use numbering space in the data items		o Reservation of a Private Use numbering space within the data items
	repository for experimental data items.		repository for experimental data items.
	o A new repository for DLEP status codes, with eight (8) currently		o A new repository for DLEP status codes, with eight (8) currently
	assigned.		assigned.
	o Reservation of a Private Use numbering space in the status codes		o Reservation of a Private Use numbering space within the status
	repository for experimental status codes.		codes repository for experimental status codes.
	o A new repository for DLEP extensions, with one (1) value currently		o A new repository for DLEP extensions, with one (1) value currently
	assigned.		assigned.
	o Reservation of a Private Use numbering space in the extension		o Reservation of a Private Use numbering space within the extension
	repository for experimental extensions.		repository for experimental extensions.
	o A request for allocation of a well-known port for DLEP TCP and UDP		o A request for allocation of a well-known port for DLEP TCP and UDP
	communication.		communication.
	o A request for allocation of a multicast IP address for DLEP		o A request for allocation of a link-local multicast IPv4 address
	discovery.		for DLEP discovery.
	12.2. Expert Review: Evaluation Guidelines
	No additional guidelines for expert review are anticipated.		o A request for allocation of a link-local multicast IPv6 address
			for DLEP discovery.
	12.3. Signal/Message Type Registration		13.2. Signal/Message Type Registration
	A new repository must be created with the values of the DLEP signals		A new repository must be created with the values of the DLEP signals
	and messages.		and messages, entitled "Message Type Values for the Dynamic Link
			Event Protocol (DLEP)". The repository is to be managed using the
			"Specification Required" policy documented in [RFC5226].
	All signal and message values are in the range [0..65535], defined in		All signal and message values are in the range [0..65535], defined in
	Table 1.		Table 1.
	12.4. DLEP Data Item Registrations		13.3. DLEP Data Item Registrations
	A new repository for DLEP data items must be created.		A new repository for DLEP data items must be created, entitled "Data
			Item Type Values for the Dynamic Link Event Protocol (DLEP)". The
			repository is to be managed using the "Specification Required" policy
			documented in [RFC5226].
	All data item values are in the range [0..65535], defined in Table 2.		All data item values are in the range [0..65535], defined in Table 2.
	12.5. DLEP Status Code Registrations		13.4. DLEP Status Code Registrations
	A new repository for DLEP status codes must be created.		A new repository for DLEP status codes must be created, entitled
			"Status Code Values for the Dynamic Link Event Protocol (DLEP)". The
			repository is to be managed using the "Specification Required" policy
			documented in [RFC5226].
	All status codes are in the range [0..255], defined in Table 3.		All status codes are in the range [0..255], defined in Table 3.
	12.6. DLEP Extensions Registrations		13.5. DLEP Extensions Registrations
	A new repository for DLEP extensions must be created.		A new repository for DLEP extensions must be created, entitled
			"Extension Type Values for the Dynamic Link Event Protocol (DLEP)".
			The repository is to be managed using the "Specification Required"
			policy documented in [RFC5226].
	All extension values are in the range [0..65535]. Current		All extension values are in the range [0..65535]. Current
	allocations are:		allocations are:
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	| Code | Description |		| Code | Description |
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	| 0 | Reserved |		| 0 | Reserved |
	| 1 | Credit Windowing |		| 1 | Credit Windowing |
	| 2-65519 | Reserved for future extensions |		| 2-65519 | Unassigned. Available for future extensions |
	| 65520-65534 | Private Use. Available for experiments |		| 65520-65534 | Private Use. Available for experiments |
	| 65535 | Reserved |		| 65535 | Reserved |
	+-------------+-----------------------------------------------------+		+-------------+-----------------------------------------------------+
	Table 4: DLEP Extension types		Table 4: DLEP Extension types
	12.7. DLEP Well-known Port		13.6. DLEP Well-known Port
	It is requested that IANA allocate a single well-known port number		It is requested that IANA allocate a single well-known port number
	for both TCP and UDP, for DLEP communication. SCTP port allocation		for both TCP and UDP, for DLEP communication. SCTP port allocation
	is not required.		is not required.
	12.8. DLEP IPv6 Link-local Multicast Address		13.7. DLEP IPv4 Link-local Multicast Address
			It is requested that IANA allocate an IPv4 link-local multicast
			address for DLEP discovery signals.
			13.8. DLEP IPv6 Link-local Multicast Address
	It is requested that IANA allocate an IPv6 link-local multicast		It is requested that IANA allocate an IPv6 link-local multicast
	address for DLEP discovery signals.		address for DLEP discovery signals.
	13. Acknowledgements		14. Acknowledgements
	We would like to acknowledge and thank the members of the DLEP design		We would like to acknowledge and thank the members of the DLEP design
	team, who have provided invaluable insight. The members of the		team, who have provided invaluable insight. The members of the
	design team are: Teco Boot, Bow-Nan Cheng, John Dowdell, and Henning		design team are: Teco Boot, Bow-Nan Cheng, John Dowdell, and Henning
	Rogge.		Rogge.
	We would also like to acknowledge the influence and contributions of		We would also like to acknowledge the influence and contributions of
	Greg Harrison, Chris Olsen, Martin Duke, Subir Das, Jaewon Kang,		Greg Harrison, Chris Olsen, Martin Duke, Subir Das, Jaewon Kang,
	Vikram Kaul, Nelson Powell and Victoria Mercieca.		Vikram Kaul, Nelson Powell, Lou Berger, and Victoria Mercieca.
	14. References		15. References
	14.1. Normative References		15.1. Normative References
	[CREDIT] Ratliff, S., "Credit Windowing extension for DLEP", draft-		[CREDIT] Ratliff, S., "Credit Windowing extension for DLEP", draft-
	ietf-manet-credit-window-00 IETF draft, October 2015.		ietf-manet-credit-window-00 IETF draft, October 2015.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/		Requirement Levels", BCP 14, RFC 2119,
	RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	14.2. Informative References		15.2. Informative References
	[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security		[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
	(TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/		IANA Considerations Section in RFCs", BCP 26, RFC 5226,
	RFC5246, August 2008,		DOI 10.17487/RFC5226, May 2008,
	<http://www.rfc-editor.org/info/rfc5246>.		<http://www.rfc-editor.org/info/rfc5226>.
	[RFC5578] Berry, B., Ed., Ratliff, S., Paradise, E., Kaiser, T., and		[RFC5578] Berry, B., Ed., Ratliff, S., Paradise, E., Kaiser, T., and
	M. Adams, "PPP over Ethernet (PPPoE) Extensions for Credit		M. Adams, "PPP over Ethernet (PPPoE) Extensions for Credit
	Flow and Link Metrics", RFC 5578, DOI 10.17487/RFC5578,		Flow and Link Metrics", RFC 5578, DOI 10.17487/RFC5578,
	February 2010, <http://www.rfc-editor.org/info/rfc5578>.		February 2010, <http://www.rfc-editor.org/info/rfc5578>.
	Appendix A. Discovery Signal Flows		Appendix A. Discovery Signal Flows
	Router Modem Signal Description		Router Modem Signal Description
	========================================================================		========================================================================
	| Router initiates discovery, starts		| Router initiates discovery, starts
	| a timer, send Peer Discovery		| a timer, send Peer Discovery
	|-------Peer Discovery---->|| signal.		|-------Peer Discovery---->|| signal.
	~ ~ ~ ~ ~ ~ ~ Router discovery timer expires		~ ~ ~ ~ ~ ~ ~ Router discovery timer expires
	without receiving Peer Offer.		without receiving Peer Offer.
	skipping to change at page 56, line 34 ¶		skipping to change at page 60, line 31 ¶
	|<--------Peer Offer-------------| Connection Point information.		|<--------Peer Offer-------------| Connection Point information.
	:		:
	: Router MAY cancel discovery timer		: Router MAY cancel discovery timer
	: and stop sending Peer Discovery		: and stop sending Peer Discovery
	: signals.		: signals.
	Appendix B. Peer Level Message Flows		Appendix B. Peer Level Message Flows
	B.1. Session Initialization		B.1. Session Initialization
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	| Router connects to discovered or		| Router connects to discovered or
	| pre-configured Modem Connection		| pre-configured Modem Connection
	|---------TCP connect----------> Point.		|---------TCP connect----------> Point.
	|		|
	| Router sends Session Initialization		| Router sends Session
	|----Session Initialization----->| message.		|----Session Initialization----->| Initialization message.
	|		|
	| Modem receives Session Initialization		| Modem receives Session
	| message.		| Initialization message.
	|		|
	| Modem sends Session Initialization		| Modem sends Session Initialization
	|<--Session Initialization Resp.-| Response, with Success status data item.		|<--Session Initialization Resp.-| Response, with Success status data
			| | item.
	| |		| |
	|<<============================>>| Session established. Heartbeats		|<<============================>>| Session established. Heartbeats
	: : begin.		: : begin.
	B.2. Session Initialization - Refused		B.2. Session Initialization - Refused
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	| Router connects to discovered or		| Router connects to discovered or
	| pre-configured Modem Connection		| pre-configured Modem Connection
	|---------TCP connect----------> Point.		|---------TCP connect----------> Point.
	|		|
	| Router sends Session Initialization		| Router sends Session
	|-----Session Initialization---->| message.		|-----Session Initialization---->| Initialization message.
	|		|
	| Modem receives Session Initialization		| Modem receives Session
	| message, and will not support the		| Initialization message, and will
	| advertised extensions.		| not support the advertised
			| extensions.
	|		|
	| Modem sends Session Initialization		| Modem sends Session Initialization
	| Response, with 'Request Denied' status		| Response, with 'Request Denied'
	|<-Session Initialization Resp.--| data item.		|<-Session Initialization Resp.--| status data item.
	|		|
	|		|
	| Router receives negative Session		| Router receives negative Session
	| Initialization Response, closes		| Initialization Response, closes
	||---------TCP close------------|| TCP connection.		||---------TCP close------------|| TCP connection.
	B.3. Router Changes IP Addresses		B.3. Router Changes IP Addresses
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	| Router sends Session Update message to		| Router sends Session Update
	|-------Session Update---------->| announce change of IP address		|-------Session Update---------->| message to announce change of IP
			| address
	|		|
	| Modem receives Session Update message		| Modem receives Session Update
	| and updates internal state.		| message and updates internal
			| state.
	|		|
	|<----Session Update Response----| Modem sends Session Update Response.		|<----Session Update Response----| Modem sends Session Update
			| Response.
	B.4. Modem Changes Session-wide Metrics		B.4. Modem Changes Session-wide Metrics
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	| Modem sends Session Update message to		| Modem sends Session Update message
	| announce change of modem-wide		| to announce change of modem-wide
	|<--------Session Update---------| metrics		|<--------Session Update---------| metrics
	|		|
	| Router receives Session Update message		| Router receives Session Update
	| and updates internal state.		| message and updates internal
			| state.
	|		|
	|----Session Update Response---->| Router sends Session Update Response.		|----Session Update Response---->| Router sends Session Update
			| Response.
	B.5. Router Terminates Session		B.5. Router Terminates Session
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	| Router sends Session Termination		| Router sends Session Termination
	|------Session Termination------>| message with Status data item.		|------Session Termination------>| message with Status data item.
	| |		| |
	|-------TCP shutdown (send)---> | Router stops sending messages.		|-------TCP shutdown (send)---> | Router stops sending messages.
	|		|
	| Modem receives Session Termination,		| Modem receives Session
	| stops counting received heartbeats		| Termination, stops counting
	| and stops sending heartbeats.		| received heartbeats and stops
			| sending heartbeats.
	|		|
	| Modem sends Session Termination Response		| Modem sends Session Termination
	|<---Session Termination Resp.---| with Status 'Success'.		|<---Session Termination Resp.---| Response with Status 'Success'.
	|		|
	| Modem stops sending messages.		| Modem stops sending messages.
	|		|
	||---------TCP close------------|| Session terminated.		||---------TCP close------------|| Session terminated.
	B.6. Modem Terminates Session		B.6. Modem Terminates Session
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	| Modem sends Session Termination		| Modem sends Session Termination
	|<----Session Termination--------| message with Status data item.		|<----Session Termination--------| message with Status data item.
	|		|
	| Modem stops sending messages.		| Modem stops sending messages.
	|		|
	| Router receives Session Termination,		| Router receives Session
	| stops counting received heartbeats		| Termination, stops counting
	| and stops sending heartbeats.		| received heartbeats and stops
			| sending heartbeats.
	|		|
	| Router sends Session Termination Response		| Router sends Session Termination
	|---Session Termination Resp.--->| with Status 'Success'.		|---Session Termination Resp.--->| Response with Status 'Success'.
	|		|
	| Router stops sending messages.		| Router stops sending messages.
	|		|
	||---------TCP close------------|| Session terminated.		||---------TCP close------------|| Session terminated.
	B.7. Session Heartbeats		B.7. Session Heartbeats
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	|----------Heartbeat------------>| Router sends heartbeat message		|----------Heartbeat------------>| Router sends heartbeat message
	|		|
	| Modem resets heartbeats missed		| Modem resets heartbeats missed
	| counter.		| counter.
	~ ~ ~ ~ ~ ~ ~		~ ~ ~ ~ ~ ~ ~
	|---------[Any message]--------->| When the Modem receives any message		|---------[Any message]--------->| When the Modem receives any
	| from the Router.		| message from the Router.
	|		|
	| Modem resets heartbeats missed		| Modem resets heartbeats missed
	| counter.		| counter.
	~ ~ ~ ~ ~ ~ ~		~ ~ ~ ~ ~ ~ ~
	|<---------Heartbeat-------------| Modem sends heartbeat message		|<---------Heartbeat-------------| Modem sends heartbeat message
	|		|
	| Router resets heartbeats missed		| Router resets heartbeats missed
	| counter.		| counter.
	skipping to change at page 60, line 37 ¶		skipping to change at page 64, line 37 ¶
	~ ~ ~ ~ ~ ~ ~		~ ~ ~ ~ ~ ~ ~
	|<--------[Any message]----------| When the Router receives any		|<--------[Any message]----------| When the Router receives any
	| message from the Modem.		| message from the Modem.
	|		|
	| Modem resets heartbeats missed		| Modem resets heartbeats missed
	| counter.		| counter.
	B.8. Router Detects a Heartbeat timeout		B.8. Router Detects a Heartbeat timeout
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	||<----------------------| Router misses a heartbeat		||<----------------------| Router misses a heartbeat
	| ||<----------------------| Router misses too many heartbeats		| ||<----------------------| Router misses too many heartbeats
	|		|
	|		|
	|------Session Termination------>| Router sends Session Termination		|------Session Termination------>| Router sends Session Termination
	| message with 'Timeout' Status		| message with 'Timeout' Status
	| data item.		| data item.
	:		:
	: Termination proceeds as above.		: Termination proceeds as above.
	B.9. Modem Detects a Heartbeat timeout		B.9. Modem Detects a Heartbeat timeout
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	|---------------------->|| Modem misses a heartbeat		|---------------------->|| Modem misses a heartbeat
	|---------------------->|| | Modem misses too many heartbeats		|---------------------->|| | Modem misses too many heartbeats
	|		|
	|		|
	|<-----Session Termination-------| Modem sends Session Termination		|<-----Session Termination-------| Modem sends Session Termination
	| message with 'Timeout' Status		| message with 'Timeout' Status
	| data item.		| data item.
	:		:
	: Termination proceeds as above.		: Termination proceeds as above.
	Appendix C. Destination Specific Signal Flows		Appendix C. Destination Specific Message Flows
	C.1. Common Destination Signaling
	Router Modem Signal Description		C.1. Common Destination Notification
			Router Modem Message Description
	========================================================================		========================================================================
	| Modem detects a new logical		| Modem detects a new logical
	| destination is reachable, and		| destination is reachable, and
	|<-------Destination Up----------| sends Destination Up message.		|<-------Destination Up----------| sends Destination Up message.
	|		|
	|------Destination Up Resp.----->| Router sends Destination Up Response.		|------Destination Up Resp.----->| Router sends Destination Up
			| Response.
	~ ~ ~ ~ ~ ~ ~		~ ~ ~ ~ ~ ~ ~
	| Modem detects change in logical		| Modem detects change in logical
	| destination metrics, and sends		| destination metrics, and sends
	|<-------Destination Update------| Destination Update message.		|<-------Destination Update------| Destination Update message.
	~ ~ ~ ~ ~ ~ ~		~ ~ ~ ~ ~ ~ ~
	| Modem detects change in logical		| Modem detects change in logical
	| destination metrics, and sends		| destination metrics, and sends
	|<-------Destination Update------| Destination Update message.		|<-------Destination Update------| Destination Update message.
	~ ~ ~ ~ ~ ~ ~		~ ~ ~ ~ ~ ~ ~
	| Modem detects logical destination		| Modem detects logical destination
	| is no longer reachable, and sends		| is no longer reachable, and sends
	|<-------Destination Down--------| Destination Down message.		|<-------Destination Down--------| Destination Down message.
	|		|
	| Router receives Destination Down,		| Router receives Destination Down,
	| updates internal state, and sends		| updates internal state, and sends
	|------Destination Down Resp.--->| Destination Down Response message.		|------Destination Down Resp.--->| Destination Down Response message.
	C.2. Multicast Destination Signaling		C.2. Multicast Destination Notification
			Router Modem Message Description
	Router Modem Signal Description
	========================================================================		========================================================================
	| Router detects a new multicast		| Router detects a new multicast
	| destination is in use, and sends		| destination is in use, and sends
	|--------Destination Up--------->| Destination Up message.		|--------Destination Up--------->| Destination Up message.
	|		|
	| Modem updates internal state to		| Modem updates internal state to
	| monitor multicast destination, and		| monitor multicast destination, and
	|<-----Destination Up Resp.------| sends Destination Up Response.		|<-----Destination Up Resp.------| sends Destination Up Response.
	skipping to change at page 62, line 31 ¶		skipping to change at page 67, line 28 ¶
	|<-------Destination Update------| Destination Update message.		|<-------Destination Update------| Destination Update message.
	~ ~ ~ ~ ~ ~ ~		~ ~ ~ ~ ~ ~ ~
	| Modem detects change in multicast		| Modem detects change in multicast
	| destination metrics, and sends		| destination metrics, and sends
	|<-------Destination Update------| Destination Update message.		|<-------Destination Update------| Destination Update message.
	~ ~ ~ ~ ~ ~ ~		~ ~ ~ ~ ~ ~ ~
	| Router detects multicast		| Router detects multicast
	| destination is no longer in use,		| destination is no longer in use,
	|--------Destination Down------->| and sends Destination Down message.		|--------Destination Down------->| and sends Destination Down
			| message.
	|		|
	| Modem receives Destination Down,		| Modem receives Destination Down,
	| updates internal state, and sends		| updates internal state, and sends
	|<-----Destination Down Resp.----| Destination Down Response message.		|<-----Destination Down Resp.----| Destination Down Response message.
	C.3. Link Characteristics Request		C.3. Link Characteristics Request
	Router Modem Signal Description		Router Modem Message Description
	========================================================================		========================================================================
	Destination has already been		Destination has already been
	~ ~ ~ ~ ~ ~ ~ announced by either peer.		~ ~ ~ ~ ~ ~ ~ announced by either peer.
	| Router requires different		| Router requires different
	| Characteristics for the		| Characteristics for the
	| destination, and sends Link		| destination, and sends Link
	|--Link Characteristics Request->| Characteristics Request message.		|--Link Characteristics Request->| Characteristics Request message.
	|		|
	skipping to change at page 63, line 31 ¶		skipping to change at page 68, line 31 ¶
	Authors' Addresses		Authors' Addresses
	Stan Ratliff		Stan Ratliff
	VT iDirect		VT iDirect
	13861 Sunrise Valley Drive, Suite 300		13861 Sunrise Valley Drive, Suite 300
	Herndon, VA 20171		Herndon, VA 20171
	USA		USA
	Email: sratliff@idirect.net		Email: sratliff@idirect.net
	Bo Berry
	Shawn Jury		Shawn Jury
	Cisco Systems		Cisco Systems
	170 West Tasman Drive		170 West Tasman Drive
	San Jose, CA 95134		San Jose, CA 95134
	USA		USA
	Email: sjury@cisco.com		Email: sjury@cisco.com
	Darryl Satterwhite		Darryl Satterwhite
	Broadcom		Broadcom
	skipping to change at line 2860 ¶		skipping to change at page 69, line 13 ¶
	Email: dsatterw@broadcom.com		Email: dsatterw@broadcom.com
	Rick Taylor		Rick Taylor
	Airbus Defence & Space		Airbus Defence & Space
	Quadrant House		Quadrant House
	Celtic Springs		Celtic Springs
	Coedkernew		Coedkernew
	Newport NP10 8FZ		Newport NP10 8FZ
	UK		UK
	Email: rick.taylor@airbus.com		Email: rick.taylor@airbus.com
			Bo Berry
End of changes. 374 change blocks.
	888 lines changed or deleted		1128 lines changed or added
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