draft-ietf-mboned-addrarch-04.txt		draft-ietf-mboned-addrarch-05.txt
	Internet Engineering Task Force P. Savola		Internet Engineering Task Force P. Savola
	Internet-Draft CSC/FUNET		Internet-Draft CSC/FUNET
	Obsoletes: 2776,2908,2909 (if March 3, 2006		Obsoletes: 2776,2908,2909 October 16, 2006
	approved)		(if approved)
	Intended status: Best Current		Intended status: Best Current
	Practice		Practice
	Expires: September 4, 2006		Expires: April 19, 2007
	Overview of the Internet Multicast Addressing Architecture		Overview of the Internet Multicast Addressing Architecture
	draft-ietf-mboned-addrarch-04.txt		draft-ietf-mboned-addrarch-05.txt
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
	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 page 1, line 37		skipping to change at page 1, line 37
	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."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	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 Internet-Draft will expire on September 4, 2006.		This Internet-Draft will expire on April 19, 2007.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2006).		Copyright (C) The Internet Society (2006).
	Abstract		Abstract
	The lack of up-to-date documentation on IP multicast address		The lack of up-to-date documentation on IP multicast address
	allocation and assignment procedures has caused a great deal of		allocation and assignment procedures has caused a great deal of
	confusion. To clarify the situation, this memo describes the		confusion. To clarify the situation, this memo describes the
	skipping to change at page 2, line 20		skipping to change at page 2, line 20
	2.1. Derived Allocation . . . . . . . . . . . . . . . . . . . . 4		2.1. Derived Allocation . . . . . . . . . . . . . . . . . . . . 4
	2.1.1. GLOP Allocation . . . . . . . . . . . . . . . . . . . 4		2.1.1. GLOP Allocation . . . . . . . . . . . . . . . . . . . 4
	2.1.2. Unicast-prefix -based Allocation . . . . . . . . . . . 4		2.1.2. Unicast-prefix -based Allocation . . . . . . . . . . . 4
	2.2. Administratively Scoped Allocation . . . . . . . . . . . . 5		2.2. Administratively Scoped Allocation . . . . . . . . . . . . 5
	2.3. Static IANA Allocation . . . . . . . . . . . . . . . . . . 6		2.3. Static IANA Allocation . . . . . . . . . . . . . . . . . . 6
	2.4. Dynamic Allocation . . . . . . . . . . . . . . . . . . . . 6		2.4. Dynamic Allocation . . . . . . . . . . . . . . . . . . . . 6
	3. Multicast Address Assignment . . . . . . . . . . . . . . . . . 6		3. Multicast Address Assignment . . . . . . . . . . . . . . . . . 6
	3.1. Derived Assignment . . . . . . . . . . . . . . . . . . . . 7		3.1. Derived Assignment . . . . . . . . . . . . . . . . . . . . 7
	3.2. SSM Assignment inside the Node . . . . . . . . . . . . . . 7		3.2. SSM Assignment inside the Node . . . . . . . . . . . . . . 7
	3.3. Manually Configured Assignment . . . . . . . . . . . . . . 7		3.3. Manually Configured Assignment . . . . . . . . . . . . . . 7
	3.4. Static IANA Assignment . . . . . . . . . . . . . . . . . . 7		3.4. Static IANA Assignment . . . . . . . . . . . . . . . . . . 8
	3.4.1. Global IANA Assignment . . . . . . . . . . . . . . . . 8		3.4.1. Global IANA Assignment . . . . . . . . . . . . . . . . 8
	3.4.2. Scope-relative IANA Assignment . . . . . . . . . . . . 8		3.4.2. Scope-relative IANA Assignment . . . . . . . . . . . . 8
	3.5. Dynamic Assignments . . . . . . . . . . . . . . . . . . . 8		3.5. Dynamic Assignments . . . . . . . . . . . . . . . . . . . 9
	4. Summary and Future Directions . . . . . . . . . . . . . . . . 9		4. Summary and Future Directions . . . . . . . . . . . . . . . . 10
	4.1. Prefix Allocation . . . . . . . . . . . . . . . . . . . . 10		4.1. Prefix Allocation . . . . . . . . . . . . . . . . . . . . 10
	4.2. Address Assignment . . . . . . . . . . . . . . . . . . . . 11		4.2. Address Assignment . . . . . . . . . . . . . . . . . . . . 11
	4.3. Future Actions . . . . . . . . . . . . . . . . . . . . . . 11		4.3. Future Actions . . . . . . . . . . . . . . . . . . . . . . 11
	5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12		5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 12		7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13		8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
	8.1. Normative References . . . . . . . . . . . . . . . . . . . 13		8.1. Normative References . . . . . . . . . . . . . . . . . . . 13
	8.2. Informative References . . . . . . . . . . . . . . . . . . 13		8.2. Informative References . . . . . . . . . . . . . . . . . . 13
	Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . . 15		Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . . 15
	A.1. Changes since -01 . . . . . . . . . . . . . . . . . . . . 15		A.1. Changes between -04 and -05 . . . . . . . . . . . . . . . 15
			A.2. Changes between -03 and -04 . . . . . . . . . . . . . . . 16
			A.3. Changes between -02 and -03 . . . . . . . . . . . . . . . 16
			A.4. Changes between -01 and -02 . . . . . . . . . . . . . . . 16
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16
	Intellectual Property and Copyright Statements . . . . . . . . . . 17		Intellectual Property and Copyright Statements . . . . . . . . . . 17
	1. Introduction		1. Introduction
	Good, up-to-date documentation of IP multicast is close to non-		Good, up-to-date documentation of IP multicast is close to non-
	existent. Particularly, this is an issue with multicast address		existent. Particularly, this is an issue with multicast address
	allocations (to networks and sites) and assignments (to hosts and		allocations (to networks and sites) and assignments (to hosts and
	applications). This problem is stressed by the fact that there		applications). This problem is stressed by the fact that there
	exists confusing or misleading documentation on the subject		exists confusing or misleading documentation on the subject
	[RFC2908]. The consequence is that those who wish to learn of IP		[RFC2908]. The consequence is that those who wish to learn about IP
	multicast and how the addressing works do not get a clear view of the		multicast and how the addressing works do not get a clear view of the
	current situation.		current situation.
	The aim of this document is to provide a brief overview of multicast		The aim of this document is to provide a brief overview of multicast
	addressing and allocation techniques. The term 'addressing		addressing and allocation techniques. The term 'addressing
	architecture' refers to the set of addressing mechanisms and methods		architecture' refers to the set of addressing mechanisms and methods
	in an informal manner.		in an informal manner.
	It is important to note that Source-specific Multicast (SSM)		It is important to note that Source-specific Multicast (SSM)
	[I-D.ietf-ssm-arch] does not have these addressing problems; hence,		[RFC4607] does not have these addressing problems because SSM group
	this document focuses on the Any Source Multicast (ASM) model.		addresses have only local significance; hence, this document focuses
			on the Any Source Multicast (ASM) model.
	This memo obsoletes RFCs 2776, 2908, and 2909 and re-classifies them		This memo obsoletes RFCs 2776, 2908, and 2909 and re-classifies them
	Historic.		Historic.
	1.1. Terminology: Allocation or Assignment		1.1. Terminology: Allocation or Assignment
	Almost all multicast documents and many other RFCs (such as DHCPv4		Almost all multicast documents and many other RFCs (such as DHCPv4
	[RFC2131] and DHCPv6 [RFC3315]) have used the terms address		[RFC2131] and DHCPv6 [RFC3315]) have used the terms address
	"allocation" and "assignment" interchangeably. However, the operator		"allocation" and "assignment" interchangeably. However, the operator
	and address management communities use these for two conceptually		and address management communities use these terms for two
	different processes.		conceptually different processes.
	In unicast operations, address allocations refer to leasing a large		In unicast operations, address allocations refer to leasing a large
	block of addresses from Internet Assigned Numbers Authority (IANA) to		block of addresses from Internet Assigned Numbers Authority (IANA) to
	a Regional Internet Registry (RIR) or from RIR to a Local Internet		a Regional Internet Registry (RIR) or from RIR to a Local Internet
	Registry (LIR) possibly through a National Internet Registry (NIR).		Registry (LIR) possibly through a National Internet Registry (NIR).
	Address assignments, on the other hand, are the leases of smaller		Address assignments, on the other hand, are the leases of smaller
	address blocks or even single addresses to the end-user sites or end-		address blocks or even single addresses to the end-user sites or end-
	users themselves.		users themselves.
	Therefore, in this memo, we will separate the two different		Therefore, in this memo, we will separate the two different
	skipping to change at page 4, line 19		skipping to change at page 4, line 19
	number of ways as described below.		number of ways as described below.
	Note that these are all only pertinent to ASM -- SSM requires no		Note that these are all only pertinent to ASM -- SSM requires no
	address block allocation because the group address has only local		address block allocation because the group address has only local
	significance (however, we discuss the address assignment inside the		significance (however, we discuss the address assignment inside the
	node in Section 3.2).		node in Section 3.2).
	2.1. Derived Allocation		2.1. Derived Allocation
	Derived allocations take the unicast prefix or some other properties		Derived allocations take the unicast prefix or some other properties
	of the network to determine unique multicast address allocations.		of the network (e.g., an autonomous system (AS) number) to determine
			unique multicast address allocations.
	2.1.1. GLOP Allocation		2.1.1. GLOP Allocation
	GLOP address allocation [RFC3180] inserts the 16-bit public		GLOP address allocation [RFC3180] inserts the 16-bit public AS number
	Autonomous System (AS) number in the middle of the IPv4 multicast		in the middle of the IPv4 multicast prefix 233.0.0.0/8, so that each
	prefix 233.0.0.0/8, so that each AS number can get a /24 worth of		AS number can get a /24 worth of multicast addresses. While this is
	multicast addresses. While this is sufficient for multicast testing		sufficient for multicast testing or small scale use, it might not be
	or small scale use, it might not be sufficient in all cases for		sufficient in all cases for extensive multicast use.
	extensive multicast use.
	A minor operational debugging issue with GLOP addresses is that the		A minor operational debugging issue with GLOP addresses is that the
	connection between the AS and the prefix is not apparent from the		connection between the AS and the prefix is not apparent from the
	prefix when the AS number is greater than 255, but has to be		prefix when the AS number is greater than 255, but has to be
	calculated (e.g., from [RFC3180], AS 5662 maps to 233.22.30.0/24). A		calculated (e.g., from [RFC3180], AS 5662 maps to 233.22.30.0/24). A
	usage issue is that GLOP addresses are not tied to any prefix but to		usage issue is that GLOP addresses are not tied to any prefix but to
	routing domains, so they cannot be used or calculated automatically.		routing domains, so they cannot be used or calculated automatically.
			GLOP allocation algorithm has not been defined for IPv6 multicast
			because the unicast-prefix -based allocation (described below)
			addresses the same need in a simpler fashion. GLOP hasn't been (and
			likely never will be) specified for 4-byte AS numbers
			[I-D.ietf-idr-as4bytes].
	2.1.2. Unicast-prefix -based Allocation		2.1.2. Unicast-prefix -based Allocation
	RFC 3306 [RFC3306] describes a mechanism which embeds up to 64 first		RFC 3306 [RFC3306] describes a mechanism which embeds up to 64 high-
	bits of an IPv6 unicast address in the prefix part of the IPv6		order bits of an IPv6 unicast address in the prefix part of the IPv6
	multicast address, leaving at least 32 bits of group-id space		multicast address, leaving at least 32 bits of group-id space
	available after the prefix mapping.		available after the prefix mapping.
	A similar mapping has been proposed for IPv4		A similar mapping has been proposed for IPv4
	[I-D.ietf-mboned-ipv4-uni-based-mcast], but it provides a rather low		[I-D.ietf-mboned-ipv4-uni-based-mcast], but it provides a rather low
	amount of addresses (e.g., 1 per an IPv4 /24 block). While there		amount of addresses (e.g., 1 per an IPv4 /24 block). Although large
	exist large networks without an AS number of their own, this has not		networks without an AS number do exist, this technique has not been
	been seen to add sufficient value compared to GLOP addressing.		seen to add value compared to GLOP addressing.
	The IPv6 unicast-prefix-based allocations are an extremely useful way		The IPv6 unicast-prefix-based allocations are an extremely useful way
	to allow each network operator, even each subnet, obtain multicast		to allow each network operator, even each subnet, to obtain multicast
	addresses easily, through an easy computation. Further, as the IPv6		addresses easily, through an easy computation. Further, as the IPv6
	multicast header also includes the scope value [RFC3513], multicast		multicast header also includes the scope value [RFC3513], multicast
	groups of smaller scope can also be used with the same mapping.		groups of smaller scope can also be used with the same mapping.
	The IPv6 Embedded RP technique [RFC3956], used with Protocol		The IPv6 Embedded RP technique [RFC3956], used with Protocol
	Independent Multicast - Sparse Mode (PIM-SM), further leverages the		Independent Multicast - Sparse Mode (PIM-SM), further leverages the
	unicast prefix based allocations, by embedding the unicast prefix and		unicast prefix based allocations, by embedding the unicast prefix and
	interface identifier of the PIM-SM Rendezvous Point (RP) in the		interface identifier of the PIM-SM Rendezvous Point (RP) in the
	prefix. This provides all the necessary information needed to the		prefix. This provides all the necessary information needed to the
	routing systems to run the group in either inter- or intra-domain		routing systems to run the group in either inter- or intra-domain
	operation. A difference to RFC 3306 is, however, that the hosts		operation. A difference from RFC 3306 is, however, that the hosts
	cannot calculate their "multicast prefix" automatically, as the		cannot calculate their "multicast prefix" automatically, as the
	prefix depends on the decisions of the operator setting up the RP but		prefix depends on the decisions of the operator setting up the RP,
	rather requires an assignment method.		but instead requires an assignment method.
	All the IPv6 unicast-prefix-based allocation techniques provide		All the IPv6 unicast-prefix-based allocation techniques provide
	sufficient amount of multicast address space for the network		sufficient amount of multicast address space for the network
	operators.		operators.
	2.2. Administratively Scoped Allocation		2.2. Administratively Scoped Allocation
	Administratively scoped multicast [RFC2365] is provided by two		Administratively scoped multicast address allocation [RFC2365] is
	different means: under 239.0.0.0/8 in IPv4 or by 4-bit encoding in		provided by two different means: under 239.0.0.0/8 in IPv4 or by
	the IPv6 multicast address prefix [RFC3513].		4-bit encoding in the IPv6 multicast address prefix [RFC3513].
	As IPv6 administratively scoped allocations can be handled with		Since IPv6 administratively scoped allocations can be handled with
	unicast-prefix-based multicast addressing as described in		unicast-prefix-based multicast addressing as described in
	Section 2.1.2, we'll just discuss IPv4 in this section.		Section 2.1.2, we'll just discuss IPv4 in this section.
	The IPv4 administratively scoped prefix 239.0.0.0/8 is further		The IPv4 administratively scoped prefix 239.0.0.0/8 is further
	divided to Local Scope (239.255.0.0/16) and Organization Local Scope		divided to Local Scope (239.255.0.0/16) and Organization Local Scope
	(239.192.0.0/14); other parts of the administrative scopes are either		(239.192.0.0/14); other parts of the administrative scopes are either
	reserved for expansion or undefined [RFC2365]. However, RFC 2365 is		reserved for expansion or undefined [RFC2365]. However, RFC 2365 is
	ambiguous as to whether it's the enterprises or the IETF who are		ambiguous as to whether the enterprises or the IETF are allowed to
	allowed to expand the space.		expand the space.
	Topologies which act under a single administration can easily use the		Topologies which act under a single administration can easily use the
	scoped multicast addresses for their internal groups. Groups which		scoped multicast addresses for their internal groups. Groups which
	need to be shared between multiple routing domains (but not		need to be shared between multiple routing domains (even if not
	propagated through the Internet) are more problematic and typically		propagated through the Internet) are more problematic and typically
	need an assignment of a global multicast address because their scope		need an assignment of a global multicast address because their scope
	is undefined.		is undefined.
	There is a large number of multicast applications (such as "Norton		There is a large number of multicast applications (such as "Norton
	Ghost") which are restricted either to a link or a site, and it is		Ghost") which are restricted either to a link or a site, and it is
	extremely undesirable to propagate them further (either to the rest		extremely undesirable to propagate them further (beyond the link or
	of the site, or beyond the site). Typically many such applications		the site). Typically many such applications have been given or have
	have been given or have hijacked a static IANA address assignment;		hijacked a static IANA address assignment. The fact that assignments
	this makes it challenging to implement proper propagation limiting --		to typically locally used applications come from the same range as
	which could be easier if such applications could have been assigned		global applications, implementing proper propagation limiting is
	specific administratively scoped addresses instead. This is an area		challenging. Filtering would be easier if such applications would in
	of further future work.		future be assigned specific administratively scoped addresses
			instead. This is an area of further future work.
	There has also been work on a protocol to automatically discover		There has also been work on a protocol to automatically discover
	multicast scope zones [RFC2776], but it has never been widely		multicast scope zones [RFC2776], but it has never been widely
	implemented or deployed.		implemented or deployed.
	2.3. Static IANA Allocation		2.3. Static IANA Allocation
	In some rare cases, some organizations may have been able to obtain		In some rare cases, some organizations may have been able to obtain
	static multicast address allocations (of up to 256 addresses)		static multicast address allocations (of up to 256 addresses)
	directly from IANA. Typically these have been meant as a block of		directly from IANA. Typically these have been meant as a block of
	static assignments to multicast applications, as described in		static assignments to multicast applications, as described in
	Section 3.4.1. In principle, IANA does not allocate multicast		Section 3.4.1. In principle, IANA should not and does not allocate
	address blocks to the operators but GLOP or Unicast-prefix-based		multicast address blocks to the operators but GLOP or Unicast-prefix-
	allocations should be used instead.		based allocations should be used instead.
	2.4. Dynamic Allocation		2.4. Dynamic Allocation
	RFC 2908 [RFC2908] proposed three different layers of multicast		RFC 2908 [RFC2908] proposed three different layers of multicast
	address allocation and assignment, where layers 3 (inter-domain		address allocation and assignment, where layers 3 (inter-domain
	allocation) and layer 2 (intra-domain allocation) could be applicable		allocation) and layer 2 (intra-domain allocation) could be applicable
	here. Multicast Address-Set Claim Protocol (MASC) [RFC2909] is an		here. Multicast Address-Set Claim Protocol (MASC) [RFC2909] is an
	example of the former, and Multicast Address Allocation Protocol		example of the former, and Multicast Address Allocation Protocol
	(AAP) [I-D.ietf-malloc-aap] (abandoned in 2000 due lack of interest		(AAP) [I-D.ietf-malloc-aap] (abandoned in 2000 due lack of interest
	and technical problems) is an example of the latter.		and technical problems) is an example of the latter.
	Both of the proposed allocation protocols were quite complex, and		Both of the proposed allocation protocols were quite complex, and
	have never been deployed or seriously implemented.		have never been deployed or seriously implemented.
	It can be concluded that there are no dynamic multicast address		It can be concluded that dynamic multicast address allocation
	allocation protocols, and other methods such as GLOP or unicast-		protocols provide no benefit beyond GLOP/unicast-prefix-based
	prefix-based addressing should be used instead.		mechanisms and have been abandoned.
	3. Multicast Address Assignment		3. Multicast Address Assignment
	For multicast address assignment, i.e., how an application learns the		There are a number of possible ways for an application, node or set
	address it can use, or a node (or a set of nodes) learns an address		of nodes to learn a multicast address as described below.
	it could use for an application, has a number of options as described
	below.
	Any IPv6 address assignment method should be aware of the guidelines		Any IPv6 address assignment method should be aware of the guidelines
	for the assignment of the group-IDs for IPv6 multicast addresses		for the assignment of the group-IDs for IPv6 multicast addresses
	[RFC3307].		[RFC3307].
	3.1. Derived Assignment		3.1. Derived Assignment
	There are significantly fewer options for derived address assignment		There are significantly fewer options for derived address assignment
	compared to derived allocation. Derived multicast assignment has		compared to derived allocation. Derived multicast assignment has
	only been specified for IPv6 link-scoped multicast		only been specified for IPv6 link-scoped multicast [RFC4489], where
	[I-D.ietf-ipv6-link-scoped-mcast], where the EUI64 is embedded in the		the EUI64 is embedded in the multicast address, providing a node with
	multicast address, providing a node with unique multicast addresses		unique multicast addresses for link-local ASM communications.
	for link-local ASM communications.
	3.2. SSM Assignment inside the Node		3.2. SSM Assignment inside the Node
	While the SSM multicast addresses have only local (to the node)		While the SSM multicast addresses have only local (to the node)
	significance, there is still a minor issue on how to assign the		significance, there is still a minor issue on how to assign the
	addresses between the applications running on the same node (or more		addresses between the applications running on the same IP address.
	precisely, an IP address).
	This assignment is not considered to be a problem because typically		This assignment is not considered to be a problem because typically
	the addresses for the applications are selected manually or		the addresses for the applications are selected manually or
	statically, but if done using an Application Programming Interface		statically, but if done using an Application Programming Interface
	(API), the API could check that the addresses do not conflict prior		(API), the API could check that the addresses do not conflict prior
	to assigning one.		to assigning one.
	3.3. Manually Configured Assignment		3.3. Manually Configured Assignment
	With manually configured assignment, the network operator who has a		With manually configured assignment, the network operator who has a
	skipping to change at page 8, line 27		skipping to change at page 8, line 32
	limited multicast address space.		limited multicast address space.
	[RFC3138] describes how to handle those GLOP assignments (called		[RFC3138] describes how to handle those GLOP assignments (called
	"eGLOP") which use the private-use AS number space (233.252.0.0/14).		"eGLOP") which use the private-use AS number space (233.252.0.0/14).
	It was envisioned that IANA would delegate the responsibility of		It was envisioned that IANA would delegate the responsibility of
	these to RIRs, which would assign or allocate addresses as best		these to RIRs, which would assign or allocate addresses as best
	seemed fit. However, this was never carried out as IANA did not make		seemed fit. However, this was never carried out as IANA did not make
	these allocations to RIRs due to procedural reasons.		these allocations to RIRs due to procedural reasons.
	In summary, there are applications which have obtained a global		In summary, there are applications which have obtained a global
	static IANA assignment and while some of which are really needed,		static IANA assignment and while some of the assignments were really
	some of which probably should not have been granted. Conversely,		needed, others probably should not have been granted. Conversely,
	there are some applications that have not obtained a static IANA		there are some applications that have not obtained a static IANA
	assignment, yet should have requested an assignment and been granted		assignment, yet should have requested an assignment and been granted
	one.		one.
	3.4.2. Scope-relative IANA Assignment		3.4.2. Scope-relative IANA Assignment
	IANA also assigns numbers as an integer offset from the highest		IANA also assigns numbers as an integer offset from the highest
	address in each IPv4 administrative scope as described in [RFC2365].		address in each IPv4 administrative scope as described in [RFC2365].
	For example, the SLPv2 discovery scope-relative offset is "2", so		For example, the SLPv2 discovery scope-relative offset is "2", so
	SLPv2 discovery address within IPv4 Local-Scope (239.255.0.0/16) is		SLPv2 discovery address within IPv4 Local-Scope (239.255.0.0/16) is
	skipping to change at page 9, line 10		skipping to change at page 9, line 16
	The layer 1 of RFC 2908 [RFC2908] described dynamic assignment from		The layer 1 of RFC 2908 [RFC2908] described dynamic assignment from
	Multicast Address Allocation Servers (MAAS) to applications and		Multicast Address Allocation Servers (MAAS) to applications and
	nodes, with Multicast Address Dynamic Client Allocation Protocol		nodes, with Multicast Address Dynamic Client Allocation Protocol
	(MADCAP) [RFC2730] as an example. Since then, there has been a		(MADCAP) [RFC2730] as an example. Since then, there has been a
	proposal for DHCPv6 assignment		proposal for DHCPv6 assignment
	[I-D.jdurand-assign-addr-ipv6-multicast-dhcpv6].		[I-D.jdurand-assign-addr-ipv6-multicast-dhcpv6].
	It would be rather straightforward to deploy a dynamic assignment		It would be rather straightforward to deploy a dynamic assignment
	protocol which would lease group addresses based on a multicast		protocol which would lease group addresses based on a multicast
	prefix to the applications wishing to use multicast. For example,		prefix to the applications wishing to use multicast. However, only
	only few have implemented MADCAP, and it's not significantly		few have implemented MADCAP, and it hasn't been significantly
	deployed. Moreover, it is not clear how widely for example the APIs		deployed. So, it is not clear if the lack of deployment is due to a
	for communication between the multicast application and the MADCAP		currently missing need. Moreover, it is not clear how widely for
	client operating at the host have been implemented [RFC2771].		example the APIs for communication between the multicast application
			and the MADCAP client operating at the host have been implemented
			[RFC2771].
	An entirely different approach is Session Announcement Protocol (SAP)		An entirely different approach is Session Announcement Protocol (SAP)
	[RFC2974]. In addition to advertising global multicast sessions, the		[RFC2974]. In addition to advertising global multicast sessions, the
	protocol also has associated ranges of addresses for both IPv4 and		protocol also has associated ranges of addresses for both IPv4 and
	IPv6 which can be used by SAP-aware applications to create new groups		IPv6 which can be used by SAP-aware applications to create new groups
	and new group addresses. Creating a session (and obtaining an		and new group addresses. Creating a session (and obtaining an
	address) is a rather tedious process which is why it isn't done all		address) is a rather tedious process which is why it isn't done all
	that often. (Note that the IPv6 SAP address is unroutable in the		that often. (Note that the IPv6 SAP address is unroutable in the
	inter-domain multicast.)		inter-domain multicast.)
	A conclusion about dynamic assignment protocols is that:		A conclusion about dynamic assignment protocols is that:
	1. multicast is not significantly attractive in the first place,		1. multicast is not significantly attractive in the first place,
	2. very many applications have a static IANA assignment and thus		2. most applications have a static IANA assignment and thus require
	require no dynamic or manual assignment,		no dynamic or manual assignment,
	3. those that cannot be easily satisfied with IANA or manual		3. those that cannot be easily satisfied with IANA or manual
	assignment (i.e., where dynamic assignment would be desirable)		assignment (i.e., where dynamic assignment would be desirable)
	are rather marginal, or		are rather marginal, or
	4. that there are other gaps why dynamic assignments are not seen as		4. that there are other gaps why dynamic assignments are not seen as
	a useful approach (for example, issues related to service		a useful approach (for example, issues related to service
	discovery/rendezvous).		discovery/rendezvous).
	In consequence, more work on rendezvous/service discovery would be		In consequence, more work on rendezvous/service discovery would be
	skipping to change at page 10, line 13		skipping to change at page 10, line 18
	memo, and presents some potential future directions.		memo, and presents some potential future directions.
	4.1. Prefix Allocation		4.1. Prefix Allocation
	Summary of prefix allocation methods for ASM is in Figure 1.		Summary of prefix allocation methods for ASM is in Figure 1.
	+-------+--------------------------------+--------+--------+		+-------+--------------------------------+--------+--------+
	| Sect. | Prefix allocation method | IPv4 | IPv6 |		| Sect. | Prefix allocation method | IPv4 | IPv6 |
	+-------+--------------------------------+--------+--------+		+-------+--------------------------------+--------+--------+
	| 2.1.1 | Derived: GLOP | Yes | NoNeed*|		| 2.1.1 | Derived: GLOP | Yes | NoNeed*|
	| 2.1.2 | Derived: Unicast-prefix-based |No -yet | Yes |		| 2.1.2 | Derived: Unicast-prefix-based | No | Yes |
	| 2.2 | Administratively scoped | Yes | NoNeed*|		| 2.2 | Administratively scoped | Yes | NoNeed*|
	| 2.3 | Static IANA allocation | No | No |		| 2.3 | Static IANA allocation | No | No |
	| 2.4 | Dynamic allocation protocols | No | No |		| 2.4 | Dynamic allocation protocols | No | No |
	+-------+--------------------------------+--------+--------+		+-------+--------------------------------+--------+--------+
	* = the need satisfied by IPv6 unicast-prefix-based allocation.		* = the need satisfied by IPv6 unicast-prefix-based allocation.
	Figure 1		Figure 1
	o Only ASM is affected by the assignment/allocation issues (however,		o Only ASM is affected by the assignment/allocation issues (however,
	both ASM and SSM have roughly the same address discovery issues).		both ASM and SSM have roughly the same address discovery issues).
	skipping to change at page 11, line 32		skipping to change at page 11, line 32
	o Manually configured assignment is what's typically done today, and		o Manually configured assignment is what's typically done today, and
	works to a sufficient degree in smaller scale.		works to a sufficient degree in smaller scale.
	o Global IANA assignment has been done extensively in the past, but		o Global IANA assignment has been done extensively in the past, but
	it needs to be tightened down to prevent problems caused by "land-		it needs to be tightened down to prevent problems caused by "land-
	grabbing". Scope-relative IANA assignment is acceptable but the		grabbing". Scope-relative IANA assignment is acceptable but the
	size of the pool is not very high. Inter-domain routing of IPv6		size of the pool is not very high. Inter-domain routing of IPv6
	IANA-assigned prefixes is likely going to be challenging.		IANA-assigned prefixes is likely going to be challenging.
	o Dynamic assignment, e.g., MADCAP has been implemented, but there		o Dynamic assignment, e.g., MADCAP has been implemented, but there
	is no wide deployment, so a solution is there. However, either		is no wide deployment. So, either there are other gaps in the
	there are other gaps in the multicast architecture or there is no		multicast architecture or there is no sufficient demand for it in
	sufficient demand for it in the first place when manual and static		the first place when manual and static IANA assignments are
	IANA assignments are available. Assignments using SAP also exist		available. Assignments using SAP also exist but are not common;
	but are not common; global SAP assignment is unfeasible with IPv6.		global SAP assignment is unfeasible with IPv6.
	o Derived assignments are only applicable in a fringe case of link-		o Derived assignments are only applicable in a fringe case of link-
	scoped multicast.		scoped multicast.
	4.3. Future Actions		4.3. Future Actions
	o Multicast address discovery/"rendezvous" needs to be analyzed at		o Multicast address discovery/"rendezvous" needs to be analyzed at
	more length, and an adequate solution provided; the result also		more length, and an adequate solution provided; the result also
	needs to be written down to be shown to the IANA static assignment		needs to be written down to be shown to the IANA static assignment
	requestors. See [I-D.ietf-mboned-addrdisc-problems] for more.		requestors. See [I-D.ietf-mboned-addrdisc-problems] for more.
	skipping to change at page 12, line 19		skipping to change at page 12, line 19
	use global addresses which should never leak in any case).		use global addresses which should never leak in any case).
	o The IETF should seriously consider its static IANA allocations		o The IETF should seriously consider its static IANA allocations
	policy, e.g., "locking it down" to a stricter policy (like "IETF		policy, e.g., "locking it down" to a stricter policy (like "IETF
	Consensus") and looking at developing the discovery/rendezvous		Consensus") and looking at developing the discovery/rendezvous
	functions, if necessary.		functions, if necessary.
	5. Acknowledgements		5. Acknowledgements
	Tutoring a couple multicast-related papers, the latest by Kaarle		Tutoring a couple multicast-related papers, the latest by Kaarle
	Ritvanen [RITVANEN] convinced the author that the up-to-date		Ritvanen [RITVANEN] convinced the author that updated multicast
	multicast address assignment/allocation documentation is necessary.		address assignment/allocation documentation is needed.
	Multicast address allocations/assignments were discussed at the		Multicast address allocations/assignments were discussed at the
	MBONED WG session at IETF59 [MBONED-IETF59].		MBONED WG session at IETF59 [MBONED-IETF59].
	Dave Thaler, James Lingard, and Beau Williamson provided useful		Dave Thaler, James Lingard, and Beau Williamson provided useful
	feedback for the preliminary version of this memo. Myung-Ki Shin,		feedback for the preliminary version of this memo. Myung-Ki Shin,
	Jerome Durand, John Kristoff, and Dave Price also suggested		Jerome Durand, John Kristoff, Dave Price, and Spencer Dawkins also
	improvements.		suggested improvements.
	6. IANA Considerations		6. IANA Considerations
	This memo includes no request to IANA, but as the allocation and		This memo includes no request to IANA, but as the allocation and
	assignment of multicast addresses are related to IANA functions, it		assignment of multicast addresses are related to IANA functions, it
	wouldn't hurt if the IANA reviewed this entire memo.		wouldn't hurt if the IANA reviewed this entire memo.
	IANA considerations in sections 4.1.1 and 4.1.2 of [RFC2908] still		IANA considerations in sections 4.1.1 and 4.1.2 of [RFC2908] still
	apply to the administratively scoped prefixes.		apply to the administratively scoped prefixes.
	skipping to change at page 13, line 13		skipping to change at page 13, line 13
	out of scope of this memo.		out of scope of this memo.
	Obviously, especially the dynamic assignment protocols are inherently		Obviously, especially the dynamic assignment protocols are inherently
	vulnerable to resource exhaustion attacks, as discussed e.g., in		vulnerable to resource exhaustion attacks, as discussed e.g., in
	[RFC2730].		[RFC2730].
	8. References		8. References
	8.1. Normative References		8.1. Normative References
	[I-D.ietf-ipv6-link-scoped-mcast]
	Park, J., "A Method for Generating Link Scoped IPv6
	Multicast Addresses", draft-ietf-ipv6-link-scoped-mcast-09
	(work in progress), July 2005.
	[I-D.ietf-ssm-arch]
	Holbrook, H. and B. Cain, "Source-Specific Multicast for
	IP", draft-ietf-ssm-arch-07 (work in progress),
	October 2005.
	[RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23,		[RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23,
	RFC 2365, July 1998.		RFC 2365, July 1998.
	[RFC3171] Albanna, Z., Almeroth, K., Meyer, D., and M. Schipper,		[RFC3171] Albanna, Z., Almeroth, K., Meyer, D., and M. Schipper,
	"IANA Guidelines for IPv4 Multicast Address Assignments",		"IANA Guidelines for IPv4 Multicast Address Assignments",
	BCP 51, RFC 3171, August 2001.		BCP 51, RFC 3171, August 2001.
	[RFC3180] Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8",		[RFC3180] Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8",
	BCP 53, RFC 3180, September 2001.		BCP 53, RFC 3180, September 2001.
	skipping to change at page 13, line 46		skipping to change at page 13, line 36
	[RFC3307] Haberman, B., "Allocation Guidelines for IPv6 Multicast		[RFC3307] Haberman, B., "Allocation Guidelines for IPv6 Multicast
	Addresses", RFC 3307, August 2002.		Addresses", RFC 3307, August 2002.
	[RFC3513] Hinden, R. and S. Deering, "Internet Protocol Version 6		[RFC3513] Hinden, R. and S. Deering, "Internet Protocol Version 6
	(IPv6) Addressing Architecture", RFC 3513, April 2003.		(IPv6) Addressing Architecture", RFC 3513, April 2003.
	[RFC3956] Savola, P. and B. Haberman, "Embedding the Rendezvous		[RFC3956] Savola, P. and B. Haberman, "Embedding the Rendezvous
	Point (RP) Address in an IPv6 Multicast Address",		Point (RP) Address in an IPv6 Multicast Address",
	RFC 3956, November 2004.		RFC 3956, November 2004.
			[RFC4489] Park, J-S., Shin, M-K., and H-J. Kim, "A Method for
			Generating Link-Scoped IPv6 Multicast Addresses",
			RFC 4489, April 2006.
			[RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for
			IP", RFC 4607, August 2006.
	8.2. Informative References		8.2. Informative References
			[I-D.ietf-idr-as4bytes]
			Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
			Number Space", draft-ietf-idr-as4bytes-12 (work in
			progress), November 2005.
	[I-D.ietf-malloc-aap]		[I-D.ietf-malloc-aap]
	Handley, M. and S. Hanna, "Multicast Address Allocation		Handley, M. and S. Hanna, "Multicast Address Allocation
	Protocol (AAP)", June 2000.		Protocol (AAP)", June 2000.
	[I-D.ietf-mboned-addrdisc-problems]		[I-D.ietf-mboned-addrdisc-problems]
	Savola, P., "Lightweight Multicast Address Discovery		Savola, P., "Lightweight Multicast Address Discovery
	Problem Space", draft-ietf-mboned-addrdisc-problems-01		Problem Space", draft-ietf-mboned-addrdisc-problems-02
	(work in progress), November 2005.		(work in progress), March 2006.
	[I-D.ietf-mboned-ipv4-uni-based-mcast]		[I-D.ietf-mboned-ipv4-uni-based-mcast]
	Thaler, D., "Unicast-Prefix-based IPv4 Multicast		Thaler, D., "Unicast-Prefix-based IPv4 Multicast
	Addresses", draft-ietf-mboned-ipv4-uni-based-mcast-02		Addresses", draft-ietf-mboned-ipv4-uni-based-mcast-02
	(work in progress), October 2004.		(work in progress), October 2004.
	[I-D.ietf-mboned-rfc3171bis]		[I-D.ietf-mboned-rfc3171bis]
	Albanna, Z., Almeroth, K., Cotton, M., and D. Meyer, "IANA		Albanna, Z., Almeroth, K., Cotton, M., and D. Meyer, "IANA
	Guidelines for IPv4 Multicast Address Assignments",		Guidelines for IPv4 Multicast Address Assignments",
	draft-ietf-mboned-rfc3171bis-02 (work in progress),		draft-ietf-mboned-rfc3171bis-02 (work in progress),
	skipping to change at page 15, line 36		skipping to change at page 15, line 39
	[RITVANEN]		[RITVANEN]
	Ritvanen, K., "Multicast Routing and Addressing", HUT		Ritvanen, K., "Multicast Routing and Addressing", HUT
	Report, Seminar on Internetworking, May 2004,		Report, Seminar on Internetworking, May 2004,
	<http://www.tml.hut.fi/Studies/T-110.551/2004/papers/>.		<http://www.tml.hut.fi/Studies/T-110.551/2004/papers/>.
	Appendix A. Changes		Appendix A. Changes
	(To be removed prior to publication as an RFC.)		(To be removed prior to publication as an RFC.)
	A.1. Changes since -01		A.1. Changes between -04 and -05
			o Editorial updates. These and the following are from Spencer
			Dawkins.
			o New text explictly stating that GLOP for v6 is not needed and GLOP
			for 4byte ASNs isn't (and likely won't be) defined.
			o Expand reasons for filtering difficulties with global IANA
			assignments for local apps, and that it would be easier if these
			were done from the local pool.
			o Explicitly mention dynamic allocations protocols' lack of benefit
			and abandonment.
			A.2. Changes between -03 and -04
			o S/scope-relative/administratively scoped/ and expand Static IANA
			Assignment section to two subsections; mainly from Dave Price.
			o Mention the routing challenges of IPv6 IANA assigned prefixes in
			section 4.2
			A.3. Changes between -02 and -03
			o Reword architectural implications of Static IANA and editorial
			improvements; mainly from John Kristoff.
			A.4. Changes between -01 and -02
	o Mention the mechanisms which haven't been so succesful: eGLOP and		o Mention the mechanisms which haven't been so succesful: eGLOP and
	MZAP.		MZAP.
	o Remove the appendices on multicast address discovery (a separate		o Remove the appendices on multicast address discovery (a separate
	draft now) and IPv4 unicast-prefix-based multicast addressing.		draft now) and IPv4 unicast-prefix-based multicast addressing.
	o Add a note on administraively scoped address space and the		o Add a note on administratively scoped address space and the
	expansion ambiguity.		expansion ambiguity.
	o Remove the references to draft-ietf-mboned-ipv6-issues-xx.txt		o Remove the references to draft-ietf-mboned-ipv6-issues-xx.txt
	o Minor editorial cleanups.		o Minor editorial cleanups.
	Author's Address		Author's Address
	Pekka Savola		Pekka Savola
	CSC - Scientific Computing Ltd.		CSC - Scientific Computing Ltd.
End of changes. 41 change blocks.
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