< draft-ietf-idmr-igmp-mrdisc-03.txt		draft-ietf-idmr-igmp-mrdisc-04.txt >
	IDMR Working Group S. Biswas		IDMR Working Group S. Biswas
	Internet Draft B. Cain		Internet Draft B. Cain
	draft-ietf-idmr-igmp-mrdisc-03.txt B. Haberman		draft-ietf-idmr-igmp-mrdisc-04.txt B. Haberman
	March 2000 Nortel Networks		July 2000 Nortel Networks
	September 2000		Expires January 2001
	IGMP Multicast Router Discovery		IGMP Multicast Router Discovery
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	skipping to change at line 108 ¶		skipping to change at line 108 ¶
	Multicast routers send Multicast Router Advertisements (hereafter		Multicast routers send Multicast Router Advertisements (hereafter
	called advertisements) periodically on all interfaces on which		called advertisements) periodically on all interfaces on which
	multicast forwarding is enabled.		multicast forwarding is enabled.
	Biswas, Cain, Haberman 2		Biswas, Cain, Haberman 2
	Multicast Router Advertisements are also sent in response to		Multicast Router Advertisements are also sent in response to
	Multicast Router Solicitations (hereafter called solicitations).		Multicast Router Solicitations (hereafter called solicitations).
	These are sent to solicit a response of Multicast Router		These are sent to solicit a response of Multicast Router
	Advertisements from all multicast routers on a subnet. Solicitations		Advertisements from all multicast routers on a subnet. Solicitations
	are sent to the IGMP-MRDISC multicast group.		are sent to the ALL-Routers (224.0.0.2) multicast group.
	Multicast Router Solicitations are sent whenever a router wishes to		Multicast Router Solicitations are sent whenever a device wishes to
	discover multicast routers on a directly attached subnet.		discover multicast routers on a directly attached subnet.
	Multicast Router Termination messages are sent when a router		Multicast Router Termination messages are sent when a router
	terminates its multicast routing functions.		terminates its multicast routing functions.
	All IGMP Multicast Router Discovery messages are sent with an IP TLL		All IGMP Multicast Router Discovery messages are sent with an IP TTL
	of 1 and contain the IP Router Alert Option [RFC2113] in their IP		of 1 and contain the IP Router Alert Option [RFC2113] in their IP
	header. All IGMP Multicast Router Discovery messages are sent with		header. All IGMP Multicast Router Discovery messages are sent with
	to the All-Routers multicast group (224.0.0.2).		to the All-Routers multicast group (224.0.0.2).
	Other non-IP forwarding devices (e.g. layer-2 switches) may send		Other non-IP forwarding devices (e.g. layer-2 switches) may send
	Multicast Router Solicitations to solicit Multicast Router		Multicast Router Solicitations to solicit Multicast Router
	Advertisements.		Advertisements.
	3. Multicast Router Advertisement		3. Multicast Router Advertisement
	skipping to change at line 232 ¶		skipping to change at line 232 ¶
	Value: Option dependent value		Value: Option dependent value
	3.4 Sending Multicast Router Advertisements		3.4 Sending Multicast Router Advertisements
	Router Advertisements are sent when the following events occur:		Router Advertisements are sent when the following events occur:
	o When the periodic advertisement interval timer expires.		o When the periodic advertisement interval timer expires.
	Note that it is not strictly periodic because the		Note that it is not strictly periodic because the
	advertisement interval is a random number between		advertisement interval is a random number between
	MaxAdvertisementInterval and MinAdvertisementInterval.		MaxAdvertisementInterval and MinAdvertisementInterval.
	(Default Value: 7-10 seconds).
	o After waiting for a random delay less than		o After waiting for a random delay less than
	MaxInitialAdvertisementInterval when an interface first		MaxInitialAdvertisementInterval when an interface first
	comes up, is (re)initialized, or IGMP Multicast Router		comes up, is (re)initialized, or IGMP Multicast Router
	Discovery is enabled. A router may send up to a maximum		Discovery is enabled. A router may send up to a maximum
	of MaxInitialAdvertisements advertisements, waiting for a		of MaxInitialAdvertisements advertisements, waiting for a
	random delay less than MaxInitialAdvertisementInterval		random delay less than MaxInitialAdvertisementInterval
	between each successive advertisement.		between each successive advertisement. Multiple messages
			are sent for robustness in the face of packet loss on the
			network.
	o This is to prevent an implosion of router advertisements.		This is to prevent an implosion of router advertisements. An example
	An example of this occurring would be when many routers		of this occurring would be when many routers are powered on at the
	are powered on at the same time. When a solicitation is		same time. When a solicitation is received, a router advertisement
	received, a router advertisement is sent in response with		is sent in response with a random delay less than MAX_RESPONSE_DELAY.
	a random delay less than MAX_RESPONSE_DELAY. If a		If a solicitation is received while an advertisement is pending
	solicitation is received while an advertisement is pending		(because of a recent solicitation), that solicitation will be
	(because of a recent solicitation), that solicitation will		ignored.
	be ignored.
	Whenever an advertisement is sent, the periodic advertisement		Whenever an advertisement is sent, the periodic advertisement
	interval timer may be reset.		interval timer must be reset.
	3.5 Receiving Multicast Router Advertisements		3.5 Receiving Multicast Router Advertisements
	Biswas, Cain, Haberman 5		Biswas, Cain, Haberman 5
	Upon receiving a router advertisement, routers will validate the		Upon receiving a router advertisement, devices will validate the
	message by the following criteria:		message by the following criteria:
	1. Verifying that the IGMP type is 0x24		1.
			Verifying that the IGMP type is 0x24
	2. Verifying the IGMP checksum		2.
			Verifying the IGMP checksum
	3. IP Destination Address = All-Routers multicast address		3.
			IP Destination Address = All-Routers multicast address
	A router advertisement not meeting the validity requirements will be		A router advertisement not meeting the validity requirements will be
	silently discarded. Routers MUST process all options, discarding		silently discarded. Devices MUST process all options, discarding
	options that are not recognized.		options that are not recognized.
	If a router advertisement is not received for a particular neighbor		If a router advertisement is not received for a particular neighbor
	within NeighborDeadInterval time interval, then the neighbor is		within NeighborDeadInterval time interval, then the neighbor is
	considered to be unreachable.		considered to be unreachable.
	3.6 Multicast Router Advertisement Configuration Variables		3.6 Multicast Router Advertisement Configuration Variables
	A router that implements multicast router discovery MUST allow for		A router that implements multicast router discovery MUST allow for
	the following variables to be configured by system management;		the following variables to be configured by system management;
	skipping to change at line 318 ¶		skipping to change at line 321 ¶
	Biswas, Cain, Haberman 6		Biswas, Cain, Haberman 6
	3.6.4 MaxInitialAdvertisements		3.6.4 MaxInitialAdvertisements
	The maximum number of router advertisements that will be sent on a		The maximum number of router advertisements that will be sent on a
	subnet after a router boots.		subnet after a router boots.
	Default: 3		Default: 3
	3.6.5 NeighborDeadInterval		3.6.5 NeighborDeadInterval
	The maximum time allowed before declaring that a neighbor can be		The maximum time allowed before a neighbor can be declared "dead".
	declared "dead". This variable is defined in seconds. In order for		This variable is defined in seconds. In order for all devices to have
	all routers to have a consistent state, it is necessary for the		a consistent state, it is necessary for the MaxAdvertisementInterval
	MaxAdvertisementInterval to be configured the same on all routers per		to be configured the same on all routers per subnet.
	subnet.
	Default: 3 * MaxAdvertisementInterval		Default: 3 * MaxAdvertisementInterval
	4. Multicast Router Solicitation		4. Multicast Router Solicitation
	4.1 Overview		4.1 Overview
	Multicast Router Solicitations are used to solicit Multicast Router		Multicast Router Solicitations are used to solicit Multicast Router
	Advertisements. These messages are used when a router (or other		Advertisements. These messages are used when a device wishes to
	device) wishes to discover multicast routers. Upon receiving a		discover multicast routers. Upon receiving a solicitation on an
	solicitation on an interface with IP multicast forwarding enabled,		interface with IP multicast forwarding enabled and multicast router
	router will respond with an advertisement.		discovery enabled, a router will respond with an advertisement.
	Router solicitations may be sent when a router starts up, when a		Router solicitations may be sent when a router starts up, when a
	router interface (re)initializes, or when IGMP Multicast Router		router interface (re)initializes, or when IGMP Multicast Router
	Discovery is enabled. Solicitations are sent as IGMP messages to the		Discovery is enabled. Solicitations are sent as IGMP messages to the
	All-Routers multicast address (224.0.0.2) and should be rate-limited.		All-Routers multicast address (224.0.0.2) and must be rate-limited.
	4.2 IP Header Fields		4.2 IP Header Fields
	4.2.1 Source Address		4.2.1 Source Address
	An IP address belonging to the interface from which this message is		An IP address belonging to the interface from which this message is
	sent. If multiple source addresses are configured on an interface,		sent. If multiple source addresses are configured on an interface,
	then the one chosen is implementation dependent.		then the one chosen is implementation dependent.
	If the solicitation is being sent from a device that does not have an		If the solicitation is being sent from a device that does not have an
	IP address (i.e. non-managed layer-2 switch), then the source address		IP address (i.e. non-managed layer-2 switch), then the source address
	should be set to all zeros.		should be set to all zeros.
	4.2.2 Destination Address		4.2.2 Destination Address
	Solicitation messages are sent to the All-Routers multicast address		Solicitation messages are sent to the All-Routers multicast address
	(224.0.0.2).		(224.0.0.2).
	4.2.3 Time-to-Live		4.2.3 Time-to-Live
	Biswas, Cain, Haberman 7
	The time-to-live field MUST be 1.		The time-to-live field MUST be 1.
			Biswas, Cain, Haberman 7
	4.2.4 Protocol		4.2.4 Protocol
	The protocol field is set to IGMP (2).		The protocol field is set to IGMP (2).
	4.3 Multicast Router Solicitation Message Format		4.3 Multicast Router Solicitation Message Format
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Reserved | Checksum |		| Type | Reserved | Checksum |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	4.3.1 Type Field		4.3.1 Type Field
	The type field is set to 0x25.		The type field is set to 0x25.
	4.3.2 Reserved Field		4.3.2 Reserved Field
	skipping to change at line 393 ¶		skipping to change at line 395 ¶
	4.3.3 Checksum		4.3.3 Checksum
	The checksum is the 16-bit one's complement of the one's complement		The checksum is the 16-bit one's complement of the one's complement
	sum of the IGMP message, starting with the IGMP type. For computing		sum of the IGMP message, starting with the IGMP type. For computing
	the checksum, the Checksum field is set to 0.		the checksum, the Checksum field is set to 0.
	4.4 Sending Multicast Router Solicitations		4.4 Sending Multicast Router Solicitations
	Router solicitations are sent when the following events occur:		Router solicitations are sent when the following events occur:
	1. After waiting for a random delay less than SOLICITATION_INTERVAL		1.
			After waiting for a random delay less than SOLICITATION_INTERVAL
	when an interface first comes up, is (re)initialized, or IGMP		when an interface first comes up, is (re)initialized, or IGMP
	Multicast Router Discovery is enabled. A router may send up to		Multicast Router Discovery is enabled. A router may send up to
	a maximum of MAX_SOLICITATIONS, waiting for a random delay less		a maximum of MAX_SOLICITATIONS, waiting for a random delay less
	than SOLICITATION_INTERVAL between each successive solicitation.		than SOLICITATION_INTERVAL between each successive solicitation.
	2. Optionally, for an implementation specific event. Solicitations		2.
			Optionally, for an implementation specific event. Solicitations
	MUST be rate-limited; no more than MAX_SOLICITATIONS MUST be		MUST be rate-limited; no more than MAX_SOLICITATIONS MUST be
	sent in SOLICITATION_INTERVAL seconds.		sent in SOLICITATION_INTERVAL seconds.
	4.5 Receiving Multicast Router Solicitations		4.5 Receiving Multicast Router Solicitations
	Upon receiving a router solicitation, routers will validate the		Upon receiving a router solicitation, routers will validate the
	message by:		message by:
	1. Verifying that the IGMP type is 0x25		1.
			Verifying that the IGMP type is 0x25
	2. Verifying the IGMP checksum		2.
			Verifying the IGMP checksum
	Biswas, Cain, Haberman 8		3.
	3. IP Destination Address = All-Routers multicast address		IP Destination Address = All-Routers multicast address
			Biswas, Cain, Haberman 8
	A router solicitation not meeting the validity requirements will be		A router solicitation not meeting the validity requirements will be
	silently discarded.		silently discarded.
	Solicitation message IP source addresses MUST NOT be used as part of		Solicitation message IP source addresses MUST NOT be used as part of
	the validity check.		the validity check.
	4.6 Multicast Router Solicitation Configuration Variables		4.6 Multicast Router Solicitation Configuration Variables
	There are no configurable variables with respect to router		There are no configurable variables with respect to router
	solicitations.		solicitations.
	skipping to change at line 457 ¶		skipping to change at line 464 ¶
	5.2.3 Time-to-Live		5.2.3 Time-to-Live
	The Time-to-Live field MUST be 1.		The Time-to-Live field MUST be 1.
	5.2.4 Protocol		5.2.4 Protocol
	The protocol field is set to IGMP (2).		The protocol field is set to IGMP (2).
	5.3 Multicast Router Termination Message Format		5.3 Multicast Router Termination Message Format
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Reserved | Checksum |		| Type | Reserved | Checksum |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	5.3.1 Type Field		5.3.1 Type Field
	Biswas, Cain, Haberman 9		Biswas, Cain, Haberman 9
	The type field is set to 0x26.		The type field is set to 0x26.
	5.3.2 Reserved Field		5.3.2 Reserved Field
	skipping to change at line 482 ¶		skipping to change at line 489 ¶
	5.3.3 Checksum		5.3.3 Checksum
	The checksum is the 16-bit one's complement of the one's complement		The checksum is the 16-bit one's complement of the one's complement
	sum of the IGMP message, starting with the IGMP type. For computing		sum of the IGMP message, starting with the IGMP type. For computing
	the checksum, the Checksum field is set to 0.		the checksum, the Checksum field is set to 0.
	5.4 Sending Multicast Router Termination Messages		5.4 Sending Multicast Router Termination Messages
	Multicast Router Termination messages are sent for three reasons:		Multicast Router Termination messages are sent for three reasons:
	1. Multicast forwarding is disabled on the interface		1.
			Multicast forwarding is disabled on the interface
	2. The interface is administratively disabled		2.
			The interface is administratively disabled
	3. The router is gracefully shutdown		3.
			The router is gracefully shutdown
	5.5 Receiving Multicast Router Termination Messages		5.5 Receiving Multicast Router Termination Messages
	Upon receiving a termination message, routers will validate the		Upon receiving a termination message, routers will validate the
	message by the following criteria:		message by the following criteria:
	1. Verifying that the IGMP type is 0x26		1.
			Verifying that the IGMP type is 0x26
	2. Verifying the IGMP checksum		2.
			Verifying the IGMP checksum
	3. IP Destination Address = All-Routers multicast address		3.
			IP Destination Address = All-Routers multicast address
	A termination message not meeting the validity requirements will be		A termination message not meeting the validity requirements will be
	silently discarded.		silently discarded.
	6. Multicast Router Discovery Protocol Constants		6. Multicast Router Discovery Protocol Constants
	o MAX_RESPONSE_DELAY 2 seconds		o MAX_RESPONSE_DELAY 2 seconds
	o MAX_SOLICITATION_DELAY 1 second		o MAX_SOLICITATION_DELAY 1 second
	skipping to change at line 527 ¶		skipping to change at line 540 ¶
	The following options MUST be supported by an implementation of IGMP		The following options MUST be supported by an implementation of IGMP
	Multicast Router Discovery: Query Interval Advertisement Option and		Multicast Router Discovery: Query Interval Advertisement Option and
	Robustness Variable Advertisement Option. These options advertise		Robustness Variable Advertisement Option. These options advertise
	specific IGMP variables and are sent in an advertisement depending on		specific IGMP variables and are sent in an advertisement depending on
	the version of IGMP enabled on an interface. Although no		the version of IGMP enabled on an interface. Although no
	requirements exist for multicast routers at this time, it is assumed		requirements exist for multicast routers at this time, it is assumed
	that all multicast routers support the IGMP protocol.		that all multicast routers support the IGMP protocol.
	7.2 Query Interval Advertisement Option		7.2 Query Interval Advertisement Option
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type=1 | Length=2 | IGMP Query Interval |		| Type=1 | Length=2 | IGMP Query Interval |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	If a multicast router has any version of IGMP [RFC1112] enabled on an		If a multicast router has any version of IGMP [RFC1112] enabled on an
	interface on which IGMP Multicast Router Discovery is also enabled,		interface on which IGMP Multicast Router Discovery is also enabled,
	it MUST send all advertisements with the Query Interval Advertisement		it MUST send all advertisements with the Query Interval Advertisement
	Option. This option contains the IGMP "Query Interval" configured on		Option. This option contains the IGMP "Query Interval" configured on
	the interface on which advertisements are sent.		the interface on which advertisements are sent.
	This option is sent regardless of whether the router is currently the		This option is sent regardless of whether the router is currently the
	IGMP querier for the subnet. This option is sent regardless of what		IGMP querier for the subnet. This option is sent regardless of what
	version of IGMP the router is running.		version of IGMP the router is running.
	IGMP Query Interval field is equal (in seconds) to the configured		IGMP Query Interval field is equal (in seconds) to the configured
	IGMP "query interval" on the interface from which the advertisement		IGMP "query interval" on the interface from which the advertisement
	was sent.		was sent.
	7.3 Robustness Variable Advertisement Option		7.3 Robustness Variable Advertisement Option
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type=2 | Length=2 | Robustness Variable |		| Type=2 | Length=2 | Robustness Variable |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	If a multicast router has IGMPv2 [IGMPv2] or IGMPv3 [IGMPv3] enabled		If a multicast router has IGMPv2 [IGMPv2] or IGMPv3 [IGMPv3] enabled
	on an interface on which IGMP Multicast Router Discovery is also		on an interface on which IGMP Multicast Router Discovery is also
	enabled, it MUST send all advertisements with the Robustness Variable		enabled, it MUST send all advertisements with the Robustness Variable
	Advertisement Option. This option contains the IGMP "Robustness		Advertisement Option. This option contains the IGMP "Robustness
	Variable" configured on the interface on which advertisements are		Variable" configured on the interface on which advertisements are
	sent.		sent.
	skipping to change at line 585 ¶		skipping to change at line 598 ¶
	new fields to support the discovery of multicast routers. For this		new fields to support the discovery of multicast routers. For this
	reason, the timing mechanisms defined for NDP will be used instead of		reason, the timing mechanisms defined for NDP will be used instead of
	those defined in this document for IPv4 support.		those defined in this document for IPv4 support.
	8.1 Router Advertisement Message		8.1 Router Advertisement Message
	The Router Advertisement message contains two new fields to support		The Router Advertisement message contains two new fields to support
	the multicast router discovery mechanism. The modified message		the multicast router discovery mechanism. The modified message
	format is:		format is:
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Code | Checksum |		| Type | Code | Checksum |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Cur Hop Limit |M|O|H|D|E|Rsrvd| Router Lifetime |		| Cur Hop Limit |M|O|H|D|E|Rsrvd| Router Lifetime |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Reachable Time |		| Reachable Time |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Retrans Timer |		| Retrans Timer |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Options ...		| Options ...
	+-+-+-+-+-+-+-+-+-+-		+-+-+-+-+-+-+-+-+-+-+-+-
	The two new fields are the 'D' and 'E' bits. All other fields retain		The two new fields are the 'D' and 'E' bits. All other fields retain
	their definitions and functions as described in Section 4.2 of the		their definitions and functions as described in Section 4.2 of the
	NDP specification [RFC2461].		NDP specification [RFC2461].
	8.1.1 Discovery (D) bit		8.1.1 Discovery (D) bit
	The 'D' bit is used by a router to indicate support for the Multicast		The 'D' bit is used by a router to indicate support for the Multicast
	Router Discovery protocol. A value of '1' indicates that the router		Router Discovery protocol. A value of '1' indicates that the router
	supports the discovery protocol. A value of '0' indicates no		supports the discovery protocol. A value of '0' indicates no
End of changes. 36 change blocks.
	56 lines changed or deleted		69 lines changed or added
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