draft-ietf-mboned-addrarch-02.txt		draft-ietf-mboned-addrarch-03.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 August 8, 2005		Obsoletes: 2776,2908,2909 (if October 18, 2005
	approved)		approved)
	Expires: February 9, 2006		Expires: April 21, 2006
	Overview of the Internet Multicast Addressing Architecture		Overview of the Internet Multicast Addressing Architecture
	draft-ietf-mboned-addrarch-02.txt		draft-ietf-mboned-addrarch-03.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 35		skipping to change at page 1, line 35
	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 February 9, 2006.		This Internet-Draft will expire on April 21, 2006.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2005).		Copyright (C) The Internet Society (2005).
	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
	allocation and assignment techniques and mechanisms currently (as of		allocation and assignment techniques and mechanisms currently (as of
	this writing) in use.		this writing) in use.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1 Terminology: Allocation or Assignment . . . . . . . . . . 3		1.1. Terminology: Allocation or Assignment . . . . . . . . . . 3
	2. Multicast Address Allocation . . . . . . . . . . . . . . . . . 3		2. Multicast Address Allocation . . . . . . . . . . . . . . . . . 4
	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 Scope-relative Allocation . . . . . . . . . . . . . . . . 5		2.2. Scope-relative 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 . . . . . . . . . . . . . . . . . . . . 6		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 . . . . . . . . . . . . . . . . . . 7
	3.5 Dynamic Assignments . . . . . . . . . . . . . . . . . . . 8		3.5. Dynamic Assignments . . . . . . . . . . . . . . . . . . . 8
	4. Summary and Future Directions . . . . . . . . . . . . . . . . 9		4. Summary and Future Directions . . . . . . . . . . . . . . . . 9
	4.1 Prefix Allocation . . . . . . . . . . . . . . . . . . . . 9		4.1. Prefix Allocation . . . . . . . . . . . . . . . . . . . . 9
	4.2 Address Assignment . . . . . . . . . . . . . . . . . . . . 10		4.2. Address Assignment . . . . . . . . . . . . . . . . . . . . 10
	4.3 Future Actions . . . . . . . . . . . . . . . . . . . . . . 10		4.3. Future Actions . . . . . . . . . . . . . . . . . . . . . . 11
	5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11		5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 12		7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12		8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
	8.1 Normative References . . . . . . . . . . . . . . . . . . . 12		8.1. Normative References . . . . . . . . . . . . . . . . . . . 12
	8.2 Informative References . . . . . . . . . . . . . . . . . . 13		8.2. Informative References . . . . . . . . . . . . . . . . . . 13
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . 14		Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . . 14
	A. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 14		A.1. Changes since -01 . . . . . . . . . . . . . . . . . . . . 14
	A.1 Changes since -01 . . . . . . . . . . . . . . . . . . . . 14		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15
	Intellectual Property and Copyright Statements . . . . . . . . 16		Intellectual Property and Copyright Statements . . . . . . . . . . 15
	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 of 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,		[I-D.ietf-ssm-arch] does not have these addressing problems; hence,
	this document focuses on Any Source Multicast (ASM) model.		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 for two conceptually
	different processes.		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
	skipping to change at page 4, line 12		skipping to change at page 4, line 16
	Multicast address allocation, i.e., how a network operator might be		Multicast address allocation, i.e., how a network operator might be
	able to obtain a larger block of addresses, can be handled in a		able to obtain a larger block of addresses, can be handled in a
	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 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
	Autonomous System (AS) number in the middle of the IPv4 multicast		Autonomous System (AS) number in the middle of the IPv4 multicast
	prefix 233.0.0.0/8, so that each AS number can get a /24 worth of		prefix 233.0.0.0/8, so that each AS number can get a /24 worth of
	multicast addresses. While this is sufficient for multicast testing		multicast addresses. While this is sufficient for multicast testing
	or small scale use, it might not be sufficient in all cases for		or small scale use, it might not be 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, but has to be calculated (e.g., from [RFC3180], AS 5662 maps		prefix when the AS number is greater than 255, but has to be
	to 233.22.30.0/24). A usage issue is that GLOP addresses are not		calculated (e.g., from [RFC3180], AS 5662 maps to 233.22.30.0/24). A
	tied to any prefix but to routing domains, so they cannot be used or		usage issue is that GLOP addresses are not tied to any prefix but to
	calculated automatically.		routing domains, so they cannot be used or calculated automatically.
	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 first
	bits of an IPv6 unicast address in the prefix part of the IPv6		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 [I-D.ietf-mboned-ipv4-		A similar mapping has been proposed for IPv4 [I-D.ietf-mboned-ipv4-
	uni-based-mcast], but it provides a rather low amount of addresses		uni-based-mcast], but it provides a rather low amount of addresses
	(e.g., 1 per an IPv4 /24 block). While there exist large networks		(e.g., 1 per an IPv4 /24 block). While there exist large networks
	without an AS number of their own, this has not been seen to add		without an AS number of their own, this has not been seen to add
	sufficient value compared to GLOP addressing.		sufficient value compared to GLOP addressing.
	The IPv6 unicast-prefix -based allocations are an extremely useful		The IPv6 unicast-prefix-based allocations are an extremely useful way
	way to allow each network operator, even each subnet, obtain		to allow each network operator, even each subnet, obtain multicast
	multicast addresses easily, through an easy computation. Further, as		addresses easily, through an easy computation. Further, as the IPv6
	the IPv6 multicast header also includes the scope value [RFC3513],		multicast header also includes the scope value [RFC3513], multicast
	multicast groups of smaller scope can also be used with the same		groups of smaller scope can also be used with the same mapping.
	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 to 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 but
	rather requires an assignment method.		rather 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 Scope-relative Allocation		2.2. Scope-relative Allocation
	Administratively scoped multicast [RFC2365] is provided by two		Administratively scoped multicast [RFC2365] is provided by two
	different means: under 239.0.0.0/8 in IPv4 or by 4-bit encoding in		different means: under 239.0.0.0/8 in IPv4 or by 4-bit encoding in
	the IPv6 multicast address prefix [RFC3513].		the IPv6 multicast address prefix [RFC3513].
	As IPv6 scope-relative allocations can be handled with unicast-prefix		As IPv6 scope-relative allocations can be handled with unicast-
	-based multicast addressing as described in Section 2.1.2, and there		prefix-based multicast addressing as described in Section 2.1.2, and
	is no need for separate scope-relative allocations, we'll just		there is no need for separate scope-relative allocations, we'll just
	discuss IPv4 in this section.		discuss IPv4 in this section.
	The IPv4 scope-relative prefix 239.0.0.0/8 is further divided to		The IPv4 scope-relative prefix 239.0.0.0/8 is further divided to
	Local Scope (239.255.0.0/16) and Organization Local Scope		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 it's the enterprises or the IETF who are
	allowed to expand the space.		allowed to 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 (but not
	propagated through Internet) are more problematic and typically need		propagated through the Internet) are more problematic and typically
	an assignment of a global multicast address because their scope is		need an assignment of a global multicast address because their scope
	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, but 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 (either to the rest
	of the site, or beyond the site). Typically many such applications		of the site, or beyond the site). Typically many such applications
	have been given a static IANA address assignment; this makes it		have been given or have hijacked a static IANA address assignment;
	challenging to implement proper propagation limiting -- which could		this makes it challenging to implement proper propagation limiting --
	be easier if such applications could have been assigned specific		which could be easier if such applications could have been assigned
	scope-relative addresses instead. This is an area of further future		specific scope-relative addresses instead. This is an area of
	work.		further future work.
	There has also been work on protocol to automatically discover		There has also been work on a protocol to automatically discover
	multicast scope zones [RFC2776], but it has never been seriously		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. In principle, IANA does not allocate multicast address		Section 3.4. In principle, IANA does not allocate multicast address
	blocks to the operators but GLOP or Unicast-prefix -based allocations		blocks to the operators but GLOP or Unicast-prefix -based allocations
	should be used instead.		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
	skipping to change at page 6, line 48		skipping to change at page 7, line 5
	For multicast address assignment, i.e., how an application learns the		For multicast address assignment, i.e., how an application learns the
	address it can use, or a node (or a set of nodes) learns an address		address it can use, or a node (or a set of nodes) learns an address
	it could use for an application, has a number of options as described		it could use for an application, has a number of options as described
	below.		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 [I-D.ietf-ipv6-		only been specified for IPv6 link-scoped multicast [I-D.ietf-ipv6-
	link-scoped-mcast], where the EUI64 is embedded in the multicast		link-scoped-mcast], where the EUI64 is embedded in the multicast
	address, providing a node with unique multicast addresses for link-		address, providing a node with unique multicast addresses for link-
	local ASM communications.		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 node (or more
	precisely, an 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
	multicast address prefix assigns the multicast group addresses to the		multicast address prefix assigns the multicast group addresses to the
	requesting nodes using a manual process.		requesting nodes using a manual process.
	Typically the user or administrator which wants to use a multicast		Typically the user or administrator which wants to use a multicast
	address for particular application requests an address from the		address for particular application requests an address from the
	network operator using phone, email, or similar means, and the		network operator using phone, email, or similar means, and the
	network operator provides the user with a multicast address. Then		network operator provides the user with a multicast address. Then
	the user/administrator of the node or application manually configures		the user/administrator of the node or application manually configures
	skipping to change at page 7, line 44		skipping to change at page 7, line 49
	This is a relatively simple process; it has been sufficient for		This is a relatively simple process; it has been sufficient for
	certain applications which require manual configuration in any case,		certain applications which require manual configuration in any case,
	or which cannot or do not want to justify a static IANA assignment.		or which cannot or do not want to justify a static IANA assignment.
	The manual assignment works when the number of participants in a		The manual assignment works when the number of participants in a
	group is small, as each participant has to be manually configured.		group is small, as each participant has to be manually configured.
	This is the most commonly used technique when the multicast		This is the most commonly used technique when the multicast
	application does not have a static IANA assignment.		application does not have a static IANA assignment.
	3.4 Static IANA Assignment		3.4. Static IANA Assignment
	In contrast to manually configured assignment, as described above,		In contrast to manually configured assignment, as described above,
	static IANA assignment refers to getting a globally unique assignment		static IANA assignment refers to getting a globally unique assignment
	for the particular application directly from IANA. Guidelines for		for the particular application directly from IANA. Guidelines for
	IANA are described in [RFC3171][I-D.ietf-mboned-rfc3171bis].		IANA are described in [RFC3171][I-D.ietf-mboned-rfc3171bis].
	This is seen as lucrative because it's the simplest approach for		This is seen as lucrative because it's the simplest approach for
	application developers because they can then hard-code the multicast		application developers because they can then hard-code the multicast
	address. Hard-coding requires no lease of the usable multicast		address. Hard-coding requires no lease of the usable multicast
	address, and likewise the client applications do not need to perform		address, and likewise the client applications do not need to perform
	any kind of service discovery (but depending on hard-coded		any kind of service discovery (but depending on hard-coded
	addresses). However, this is a bad approach architecturally, as we		addresses). However, there is an architectural scaling problem with
	should focus on enhancing and deploying service discovery and address		this approach, as it encourages a "land-grab" of the limited
	assignment (as needed) instead of encouraging a "land-grab" of		multicast address space.
	multicast addresses.
	[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 static IANA		In summary, there are applications which have obtained a static IANA
	assignment, some of which are really needed, and some of which		assignment and while some of which are really needed, some of which
	probably should not have been granted.		probably should not have been granted. Conversely, there are some
			applications that have not obtained a static IANA assignment, yet
			should have requested an assignment and been granted one.
	3.5 Dynamic Assignments		3.5. Dynamic Assignments
	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 [I-D.jdurand-assign-addr-ipv6-		proposal for DHCPv6 assignment [I-D.jdurand-assign-addr-ipv6-
	multicast-dhcpv6].		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
	skipping to change at page 9, line 26		skipping to change at page 9, line 30
	discovery/rendezvous).		discovery/rendezvous).
	In consequence, more work on rendezvous/service discovery would be		In consequence, more work on rendezvous/service discovery would be
	needed to make dynamic assignments more useful.		needed to make dynamic assignments more useful.
	4. Summary and Future Directions		4. Summary and Future Directions
	This section summarizes the mechanisms and analysis discussed in this		This section summarizes the mechanisms and analysis discussed in this
	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 -yet | Yes |
	| 2.2 | Separate Scope-relative | Yes | NoNeed*|		| 2.2 | Separate Scope-relative | Yes | NoNeed*|
	| 2.3 | Static IANA allocation | No | No |		| 2.3 | Static IANA allocation | No | No |
	skipping to change at page 10, line 8		skipping to change at page 10, line 16
	allocation mechanism for now, but could be extended in future.		allocation mechanism for now, but could be extended in future.
	Scope-relative allocations provide the opportunity for internal		Scope-relative allocations provide the opportunity for internal
	IPv4 allocations.		IPv4 allocations.
	o Unicast-prefix -based addresses and the derivatives provide good		o Unicast-prefix -based addresses and the derivatives provide good
	allocation strategy with IPv6, also for scoped multicast		allocation strategy with IPv6, also for scoped multicast
	addresses.		addresses.
	o Dynamic allocations are a too complex and unnecessary mechanism.		o Dynamic allocations are a too complex and unnecessary mechanism.
	o Static IANA allocations are an architecturally unacceptable		o Static IANA allocations are generally an architecturally
	approach.		unacceptable approach.
	4.2 Address Assignment		4.2. Address Assignment
	Summary of address assignment methods is in Figure 2.		Summary of address assignment methods is in Figure 2.
	+-------+--------------------------------+----------+----------+		+-------+--------------------------------+----------+----------+
	| Sect. | Address assignment method | IPv4 | IPv6 |		| Sect. | Address assignment method | IPv4 | IPv6 |
	+-------+--------------------------------+----------+----------+		+-------+--------------------------------+----------+----------+
	| 3.1 | Derived: link-scope addresses | No | Yes |		| 3.1 | Derived: link-scope addresses | No | Yes |
	| 3.2 | SSM (inside the node) | Yes | Yes |		| 3.2 | SSM (inside the node) | Yes | Yes |
	| 3.3 | Manual assignment | Yes | Yes |		| 3.3 | Manual assignment | Yes | Yes |
	| 3.4 | Static IANA/RIR assignment |LastResort|LastResort|		| 3.4 | Static IANA/RIR assignment |LastResort|LastResort|
	skipping to change at page 10, line 34		skipping to change at page 10, line 42
	Figure 2		Figure 2
	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 Static IANA assignment has been done extensively in the past, but		o Static 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".		grabbing".
	o Dynamic assignment, e.g., using MADCAP have been implemented, but		o Dynamic assignment, e.g., MADCAP has been implemented, but there
	there is no wide deployment, so a solution is there. However,		is no wide deployment, so a solution is there. However, either
	either there are other gaps in the multicast architecture or there		there are other gaps in the multicast architecture or there is no
	is no sufficient demand for it in the first place when manual and		sufficient demand for it in the first place when manual and static
	static IANA assignments are available. Assignments using SAP also		IANA assignments are available. Assignments using SAP also exist
	exist but are not common; global SAP assignment is unfeasible with		but are not common; global SAP assignment is unfeasible with IPv6.
	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.
	o IPv6 multicast DAD and/or multicast prefix communication		o IPv6 multicast DAD and/or multicast prefix communication
	mechanisms should be analyzed (e.g.,		mechanisms should be analyzed (e.g.,
	[I-D.jdurand-ipv6-multicast-ra]): whether there is demand or not,		[I-D.jdurand-ipv6-multicast-ra]): whether there is demand or not,
	and specify if yes.		and specify if yes.
	skipping to change at page 11, line 32		skipping to change at page 11, line 38
	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 the up-to-date
	multicast address assignment/allocation documentation is necessary.		multicast address assignment/allocation documentation is necessary.
	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 and		feedback for the preliminary version of this memo. Myung-Ki Shin,
	Jerome Durand also suggested improvements.		Jerome Durand, and John Kristoff also 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 12, line 18		skipping to change at page 12, line 21
	assigning multicast addresses, and this has no security		assigning multicast addresses, and this has no security
	considerations; the security analysis of the mentioned protocols is		considerations; the security analysis of the mentioned protocols is
	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]		[I-D.ietf-ipv6-link-scoped-mcast]
	Park, J., "A Method for Generating Link Scoped IPv6		Park, J., "A Method for Generating Link Scoped IPv6
	Multicast Addresses", draft-ietf-ipv6-link-scoped-mcast-09		Multicast Addresses", draft-ietf-ipv6-link-scoped-mcast-09
	(work in progress), July 2005.		(work in progress), July 2005.
	[I-D.ietf-ssm-arch]		[I-D.ietf-ssm-arch]
	Holbrook, H. and B. Cain, "Source-Specific Multicast for		Holbrook, H. and B. Cain, "Source-Specific Multicast for
	IP", draft-ietf-ssm-arch-06 (work in progress),		IP", draft-ietf-ssm-arch-07 (work in progress),
	September 2004.		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 5		skipping to change at page 13, line 10
	[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.
	8.2 Informative References		8.2. Informative References
	[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-00		Problem Space", draft-ietf-mboned-addrdisc-problems-00
	(work in progress), March 2005.		(work in progress), March 2005.
	skipping to change at page 14, line 35		skipping to change at page 14, line 41
	[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,		[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
	and M. Carney, "Dynamic Host Configuration Protocol for		and M. Carney, "Dynamic Host Configuration Protocol for
	IPv6 (DHCPv6)", RFC 3315, July 2003.		IPv6 (DHCPv6)", RFC 3315, July 2003.
	[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/>.
	Author's Address
	Pekka Savola
	CSC - Scientific Computing Ltd.
	Espoo
	Finland
	Email: psavola@funet.fi
	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 since -01
	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 scope-relative address space and the expansion		o Add a note on scope-relative address space and the expansion
	ambiguity.		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.
	Intellectual Property Statement		Author's Address
			Pekka Savola
			CSC - Scientific Computing Ltd.
			Espoo
			Finland
			Email: psavola@funet.fi
			Full Copyright Statement
			Copyright (C) The Internet Society (2005).
			This document is subject to the rights, licenses and restrictions
			contained in BCP 78, and except as set forth therein, the authors
			retain all their rights.
			This document and the information contained herein are provided on an
			"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
			OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
			ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
			INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
			INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
			WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
			Intellectual Property
	The IETF takes no position regarding the validity or scope of any		The IETF takes no position regarding the validity or scope of any
	Intellectual Property Rights or other rights that might be claimed to		Intellectual Property Rights or other rights that might be claimed to
	pertain to the implementation or use of the technology described in		pertain to the implementation or use of the technology described in
	this document or the extent to which any license under such rights		this document or the extent to which any license under such rights
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	on the procedures with respect to rights in RFC documents can be		on the procedures with respect to rights in RFC documents can be
	found in BCP 78 and BCP 79.		found in BCP 78 and BCP 79.
	skipping to change at page 16, line 29		skipping to change at page 16, line 18
	such proprietary rights by implementers or users of this		such proprietary rights by implementers or users of this
	specification can be obtained from the IETF on-line IPR repository at		specification can be obtained from the IETF on-line IPR repository at
	http://www.ietf.org/ipr.		http://www.ietf.org/ipr.
	The IETF invites any interested party to bring to its attention any		The IETF invites any interested party to bring to its attention any
	copyrights, patents or patent applications, or other proprietary		copyrights, patents or patent applications, or other proprietary
	rights that may cover technology that may be required to implement		rights that may cover technology that may be required to implement
	this standard. Please address the information to the IETF at		this standard. Please address the information to the IETF at
	ietf-ipr@ietf.org.		ietf-ipr@ietf.org.
	Disclaimer of Validity
	This document and the information contained herein are provided on an
	"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
	OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
	ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
	INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
	INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
	WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	Copyright Statement
	Copyright (C) The Internet Society (2005). This document is subject
	to the rights, licenses and restrictions contained in BCP 78, and
	except as set forth therein, the authors retain all their rights.
	Acknowledgment		Acknowledgment
	Funding for the RFC Editor function is currently provided by the		Funding for the RFC Editor function is currently provided by the
	Internet Society.		Internet Society.
End of changes. 44 change blocks.
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