< draft-ietf-magma-mrdssm-02.txt		draft-ietf-magma-mrdssm-03.txt >
	Internet Engineering Task Force MAGMA WG		Internet Engineering Task Force MAGMA WG
	INTERNET-DRAFT Isidor Kouvelas/Cisco		INTERNET-DRAFT Isidor Kouvelas/Cisco
	draft-ietf-magma-mrdssm-02.txt 26 February 2003		draft-ietf-magma-mrdssm-03.txt 17 June 2003
	Expires: August 2003		Expires: December 2003
	Multicast Router Discovery SSM Range Option		Multicast Router Discovery SSM Range Option
	Status of this Document		Status of this Document
	This document is an Internet-Draft and is in full conformance with all		This document is an Internet-Draft and is in full conformance with all
	provisions of Section 10 of RFC2026.		provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering Task		Internet-Drafts are working documents of the Internet Engineering Task
	Force (IETF), its areas, and its working groups. Note that other groups		Force (IETF), its areas, and its working groups. Note that other groups
	skipping to change at page 1, line 34 ¶		skipping to change at page 1, line 34 ¶
	http://www.ietf.org/ietf/1id-abstracts.txt		http://www.ietf.org/ietf/1id-abstracts.txt
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This document is a product of the IETF MAGMA WG. Comments should be		This document is a product of the IETF MAGMA WG. Comments should be
	addressed to the authors, or the WG's mailing list at magma@ietf.org.		addressed to the authors, or the WG's mailing list at magma@ietf.org.
	Abstract		Abstract
	This document defines the Multicast Router Discovery option		This document defines the Multicast Router Discovery protocol
	for advertising the configured IPv4 Source Specific Multicast		option for advertising the configured IPv4 Source Specific
	destination address range.		Multicast destination address range.
	1. Introduction		1. Introduction
	With current multicast deployment in the Internet, different		With current multicast deployment in the Internet, different
	multicast routing protocols coexist and operate under separate parts of		multicast routing protocols coexist and operate under separate parts of
	the multicast address space [1]. Multicast routers are consistently		the multicast address space [1]. Multicast routers are consistently
	configured with information that maps specific multicast destination		configured with information that maps specific multicast destination
	address ranges to multicast routing protocols. Part of this		address ranges to multicast routing protocols. Part of this
	configuration describes the subset of the address space that is used by		configuration describes the subset of the address space that is used by
	source-specific multicast (SSM) [2].		source-specific multicast (SSM) [3]. Under current deployment, the
			ability to extend the IPv4 SSM destination address range is used to
			define SSM destination addresses that operate within administratively
			scoped boundaries. Note that the SSM range for IPv6 is well defined for
			all valid scopes [4] and a mechanism to allow additional ranges to
			operate in SSM mode on a per-link bases is not required.
	There are currently two requirements for a router to advertise its		There are currently two requirements for a router to advertise its
	configured SSM range on its attached links:		configured SSM range on its attached links:
	o On links with multiple multicast routers, advertisement of the		o On links with multiple multicast routers, advertisement of the
	configured SSM range by each router can be used to discover miss-		configured SSM range by each router can be used to discover
	configurations.		misconfigurations.
	o IP systems with multicast sources or receivers can use the		o IP systems with multicast sources or receivers can use the
	advertisements to learn the SSM group range with which the network is		advertisements to learn the SSM group range with which the network is
	configured.		configured.
	This document defines an optional extension for the IPv4 Multicast		This document defines an optional extension for the IPv4 Multicast
	Router Discovery protocol [3] which can be used to advertise the SSM		Router Discovery protocol [2] that can be used by a router to advertise
	range. Note that the SSM range for IPv6 is well defined and a mechanism		the configured SSM address range.
	to allow additional ranges to operate in SSM mode on a per-link bases is
	not required.
	2. SSM Range Option Format		2. SSM Range Discovery Option Format
	The SSM Range option SHOULD be included in all Multicast Router		The SSM Range Discovery option SHOULD be included in all Multicast
	Advertisement messages [3]. It contains the list of multicast		Router Advertisement messages [2]. It contains the list of multicast
	destination address ranges that are configured to operate under Source		destination address ranges that are configured to operate under Source
	Specific Multicast on this router. The format of the option is as		Specific Multicast on this router. The format of the option is as
	follows:		follows:
	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=X | Length=var | Mask-Len-1 | Prefix-1 ...		| Type=X | Length=var | Mask-Len-1 | Prefix-1 ...
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Mask-Len-2 | Prefix-2 ...		| Mask-Len-2 | Prefix-2 ...
	skipping to change at page 3, line 4 ¶		skipping to change at page 3, line 13 ¶
	follows:		follows:
	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=X | Length=var | Mask-Len-1 | Prefix-1 ...		| Type=X | Length=var | Mask-Len-1 | Prefix-1 ...
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Mask-Len-2 | Prefix-2 ...		| Mask-Len-2 | Prefix-2 ...
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ... |		| ... |
	Type The type value of the Multicast Router Advertisement SSM Range		Type The type value of the Multicast Router Advertisement SSM Range
	option is X (TBD by IANA).		Discovery option is X (TBD by IANA).
	Length		Length
	The length of the SSM Range Discovery option is variable and		The length of the option in octets excluding the type and length
	depends on the number of destination ranges present in the option		fields. The length of the SSM Range Discovery option is variable
	as well as the sizes of the ranges.		and depends on the number of destination ranges present in the
			option as well as the sizes of the ranges.
	Mask-Len-n		Mask-Len-n
	The mask length for the nth address range.		The mask length in bits for the nth address range.
	Prefix-n		Prefix-n
	The multicast destination address prefix for the nth range present		The multicast destination address prefix for the nth range present
	in this option. The size of the prefix field is variable and		in this option. The size of the prefix field is variable and
	depends on the number of significant bits in the prefix (specified		depends on the number of significant bits in the prefix (specified
	in the corresponding Mask-Len field). The field is padded by enough		in the corresponding Mask-Len field). The field is padded by enough
	trailing bits to make the end of the field fall on an octet		trailing bits to make the end of the field fall on an octet
	boundary. Note that the value of the trailing bits is irrelevant.		boundary. The value of the trailing bits must be sent as zero and
			ignored on receipt. For example a prefix with a mask length field
			holding the value 16 would have a prefix field that takes up two
			octets and requires no padding. A prefix with a mask length of 17
			would have a prefix field that takes up three octets and includes 7
			trailing padding bits.
	3. Notes on Option Processing		3. Notes on Option Processing
	Routers originating Multicast Router Advertisement messages SHOULD		Routers originating Multicast Router Advertisement messages SHOULD
	NOT include more than one SSM Range Discovery option in each message.		NOT include more than one SSM Range Discovery option in each message.
	Systems with a multicast capable IP host stack that receive a Multicast		Systems with a multicast capable IP host stack that receive a Multicast
	Router Advertisement message with more than one SSM Range Discovery		Router Advertisement message with more than one SSM Range Discovery
	options MUST only use the prefixes from the last SSM Range Discovery		options MUST only use the prefixes from the last SSM Range Discovery
	option in the message as the active SSM range.		option in the message as the active SSM range.
	The SSM range specified by routers originating Multicast Router		The SSM range specified by routers originating Multicast Router
	Advertisement messages with the SSM Range Discovery option MUST not		Advertisement messages with the SSM Range Discovery option MUST not
	include any part of the link-local multicast range 224.0.0/24. Systems		include any part of the link-local multicast range 224.0.0/24. Systems
	with a multicast capable IP host stack that receive a Multicast Router		with a multicast capable IP host stack that receive a Multicast Router
	Advertisement message with a SSM Range Discovery option that includes		Advertisement message with a SSM Range Discovery option that includes
	destination addresses in the link-local multicast range 224.0.0/24 MUST		destination addresses in the link-local multicast range 224.0.0/24 MUST
	use as the active SSM range the contents of the option excluding any		use as the active SSM range the contents of the option excluding any
	addresses in the range 224.0.0/24.		addresses in the range 224.0.0/24.
	A router receiving a Multicast Router Advertisement message with an		A router receiving a Multicast Router Advertisement message with an
	SSM Range Discovery Option MUST compare the contents of the option with		SSM Range Discovery option MUST compare the contents of the option with
	the multicast address ranges in the local SSM configuration and signal		the multicast address ranges in the local SSM configuration and signal
	any differences to the administrator in a rate-limited manner.		any differences to the administrator in a rate-limited manner.
	Signaling of range differences may be accomplished by a mechanism as		Signaling of range differences may be accomplished by a mechanism as
	simple as an entry in the router log containing the address of the		simple as an entry in the router log containing the address of the
	router with the mismatch in configuration.		router with the mismatch in configuration.
	4. Security Considerations		4. Security Considerations
	Multicast Router Advertisement messages are IGMP messages sent to		Multicast Router Advertisement messages are IGMP messages sent to
	the All-Systems multicast group (224.0.0.1) which is not forwarded by		the All-Systems multicast group (224.0.0.1) which is not forwarded by
	routers. Only rogue systems on a connected link can masquerade as		routers. Only rogue systems on a connected link can masquerade as
	multicast routers. Such rogue systems can include the SSM Range		multicast routers. Such rogue systems can include the SSM Range
	Discovery option in their messages and cause the SSM range mapping to be		Discovery option in their messages and cause the SSM range mapping to be
	incorrectly set by hosts on the link. The next Multicast Router		incorrectly set by hosts on the link. The next Multicast Router
	Advertisement from a real valid router on the link will restore the		Advertisement from a real valid router on the link will restore the
	correct mapping. This spec mandates that routers log the reception of		correct mapping. This spec mandates that routers log the reception of
	inconsistent range advertisements which makes it easier to detect rogue		inconsistent range advertisements which makes it easier to detect rogue
	systems.		systems.
	5. IANA Considerations		5. IANA Considerations
	This document introduces the new SSM Range Option for the Multicast		This document introduces the new SSM Range Discovery option for the
	Router Discovery protocol. This option requires a new MRD type value to		Multicast Router Discovery protocol. This option requires a new MRD type
	be assigned by IANA.		value to be assigned by IANA.
	6. Acknowledgments		6. Acknowledgments
	The author would like to thank Bill Fenner and Dave Thaler for their		The author would like to thank Bill Fenner and Dave Thaler for their
	contribution to this document.		contribution to this document.
	7. Authors' Addresses		7. Authors' Addresses
	Isidor Kouvelas		Isidor Kouvelas
	Cisco Systems		Cisco Systems
	170 W. Tasman Drive		170 W. Tasman Drive
	San Jose, CA 95134		San Jose, CA 95134
	kouvelas@cisco.com		kouvelas@cisco.com
	8. Normative		8. Normative References
	[1] Z. Albanna, K. Almeroth, D. Meyer, M. Schipper, "IANA Guidelines for		[1] Z. Albanna, K. Almeroth, D. Meyer, M. Schipper, "IANA Guidelines for
	IPv4 Multicast Address Assignments", RFC 3171 (BCP 51), August		IPv4 Multicast Address Assignments", RFC 3171 (BCP 51), August
	2001.		2001.
	[2] H. Holbrook, B. Cain, "Source-Specific Multicast for IP", work in		[2] S. Biswas, B. Haberman, "IGMP Multicast Router Discovery", Work In
			Progress, <draft-ietf-idmr-igmp-mrdisc-??.txt>, 2002.
			9. Informative References
			[3] H. Holbrook, B. Cain, "Source-Specific Multicast for IP", work in
	progress, <draft-ietf-ssm-arch-00.txt>, 21 November 2001.		progress, <draft-ietf-ssm-arch-00.txt>, 21 November 2001.
	[3] S. Biswas, B. Haberman, "IGMP Multicast Router Discovery", Work In		[4] B. Haberman, D. Thaler, "Unicast-Prefix-based IPv6 Multicast
	Progress, <draft-ietf-idmr-igmp-mrdisc-??.txt>, 2002.		Addresses", RFC 3306, August 2002.
End of changes. 18 change blocks.
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