draft-ietf-mboned-addrarch-03.txt   draft-ietf-mboned-addrarch-04.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 October 18, 2005 Obsoletes: 2776,2908,2909 (if March 3, 2006
approved) approved)
Expires: April 21, 2006 Intended status: Best Current
Practice
Expires: September 4, 2006
Overview of the Internet Multicast Addressing Architecture Overview of the Internet Multicast Addressing Architecture
draft-ietf-mboned-addrarch-03.txt draft-ietf-mboned-addrarch-04.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 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 April 21, 2006. This Internet-Draft will expire on September 4, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). 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
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 . . . . . . . . . . . . . . . . . 4 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. 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 . . . . . . . . . . . . . . . . . . 7
3.4.1. Global IANA Assignment . . . . . . . . . . . . . . . . 8
3.4.2. Scope-relative IANA Assignment . . . . . . . . . . . . 8
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 . . . . . . . . . . . . . . . . . . . . 10
4.2. Address Assignment . . . . . . . . . . . . . . . . . . . . 10 4.2. Address Assignment . . . . . . . . . . . . . . . . . . . . 11
4.3. Future Actions . . . . . . . . . . . . . . . . . . . . . . 11 4.3. Future Actions . . . . . . . . . . . . . . . . . . . . . . 11
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . . 13 8.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . . 14 Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . . 15
A.1. Changes since -01 . . . . . . . . . . . . . . . . . . . . 14 A.1. Changes since -01 . . . . . . . . . . . . . . . . . . . . 15
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16
Intellectual Property and Copyright Statements . . . . . . . . . . 15 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 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
skipping to change at page 4, line 44 skipping to change at page 4, line 44
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.
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
uni-based-mcast], but it provides a rather low amount of addresses [I-D.ietf-mboned-ipv4-uni-based-mcast], but it provides a rather low
(e.g., 1 per an IPv4 /24 block). While there exist large networks amount of addresses (e.g., 1 per an IPv4 /24 block). While there
without an AS number of their own, this has not been seen to add exist large networks without an AS number of their own, this has not
sufficient value compared to GLOP addressing. been seen to add sufficient 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, 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
skipping to change at page 5, line 22 skipping to change at page 5, line 22
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. Administratively Scoped 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- As IPv6 administratively scoped allocations can be handled with
prefix-based multicast addressing as described in Section 2.1.2, and unicast-prefix-based multicast addressing as described in
there is no need for separate scope-relative allocations, we'll just Section 2.1.2, 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 administratively scoped prefix 239.0.0.0/8 is further
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 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 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 (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 or have hijacked a static IANA address assignment; have been given or have hijacked a static IANA address assignment;
this makes it challenging to implement proper propagation limiting -- this makes it challenging to implement proper propagation limiting --
which could be easier if such applications could have been assigned which could be easier if such applications could have been assigned
specific scope-relative addresses instead. This is an area of specific administratively scoped addresses instead. This is an area
further future work. 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. In principle, IANA does not allocate multicast address Section 3.4.1. In principle, IANA does not allocate multicast
blocks to the operators but GLOP or Unicast-prefix-based allocations address blocks to the operators but GLOP or Unicast-prefix-based
should be used instead. 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.
skipping to change at page 7, line 9 skipping to change at page 7, line 9
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
link-scoped-mcast], where the EUI64 is embedded in the multicast [I-D.ietf-ipv6-link-scoped-mcast], where the EUI64 is embedded in the
address, providing a node with unique multicast addresses for link- multicast address, providing a node with unique multicast addresses
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 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
skipping to change at page 7, line 52 skipping to change at page 7, line 52
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 an assignment for the
for the particular application directly from IANA. Guidelines for particular application directly from IANA. There are two main forms
IANA are described in [RFC3171][I-D.ietf-mboned-rfc3171bis]. of IANA assignment: global and scope-relative. Guidelines for IANA
are described in [RFC3171][I-D.ietf-mboned-rfc3171bis].
This is seen as lucrative because it's the simplest approach for 3.4.1. Global IANA Assignment
application developers because they can then hard-code the multicast
address. Hard-coding requires no lease of the usable multicast Globally unique address assignment is seen as lucrative because it's
address, and likewise the client applications do not need to perform the simplest approach for application developers since they can then
any kind of service discovery (but depending on hard-coded hard-code the multicast address. Hard-coding requires no lease of
addresses). However, there is an architectural scaling problem with the usable multicast address, and likewise the client applications do
this approach, as it encourages a "land-grab" of the limited not need to perform any kind of service discovery (but depending on
multicast address space. hard-coded addresses). However, there is an architectural scaling
problem with this approach, as it encourages a "land-grab" of the
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 static IANA In summary, there are applications which have obtained a global
assignment and while some of which are really needed, some of which static IANA assignment and while some of which are really needed,
probably should not have been granted. Conversely, there are some some of which probably should not have been granted. Conversely,
applications that have not obtained a static IANA assignment, yet there are some applications that have not obtained a static IANA
should have requested an assignment and been granted one. assignment, yet should have requested an assignment and been granted
one.
3.4.2. Scope-relative IANA Assignment
IANA also assigns numbers as an integer offset from the highest
address in each IPv4 administrative scope as described in [RFC2365].
For example, the SLPv2 discovery scope-relative offset is "2", so
SLPv2 discovery address within IPv4 Local-Scope (239.255.0.0/16) is
"239.255.255.253", within the IPv4 Organization Local-Scope
(239.192.0.0/14) it is "239.195.255.253", and so on.
Similar scope-relative assignments also exist with IPv6 [RFC2375].
As IPv6 multicast addresses have much more flexible scoping, scope-
relative assignments are also applicable to global scopes. The
assignment policies are described in [RFC3307].
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
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. For example,
only few have implemented MADCAP, and it's not significantly only few have implemented MADCAP, and it's not significantly
deployed. Moreover, it is not clear how widely for example the APIs deployed. Moreover, it is not clear how widely for example the APIs
for communication between the multicast application and the MADCAP for communication between the multicast application and the MADCAP
client operating at the host have been implemented [RFC2771]. 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)
skipping to change at page 9, line 39 skipping to change at page 10, line 14
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 | 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).
o GLOP allocations seem to provide a sufficient IPv4 multicast o GLOP allocations seem to provide a sufficient IPv4 multicast
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 Administratively scoped allocations provide the opportunity for
IPv4 allocations. internal 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 generally an architecturally o Static IANA allocations are generally an architecturally
unacceptable 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| | 3.4.1 | Global IANA/RIR assignment |LastResort|LastResort|
| 3.4.2 | Scope-relative IANA assignment | Yes | Yes |
| 3.5 | Dynamic assignment protocols | Yes | Yes | | 3.5 | Dynamic assignment protocols | Yes | Yes |
+-------+--------------------------------+----------+----------+ +--------+--------------------------------+----------+----------+
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 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". grabbing". Scope-relative IANA assignment is acceptable but the
size of the pool is not very high. Inter-domain routing of IPv6
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 a solution is there. However, either
there are other gaps in the multicast architecture or there is no there are other gaps in the multicast architecture or there is no
sufficient demand for it in the first place when manual and static sufficient demand for it in the first place when manual and static
IANA assignments are available. Assignments using SAP also exist IANA assignments are available. Assignments using SAP also exist
but are not common; global SAP assignment is unfeasible with IPv6. but are not common; 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.
skipping to change at page 11, line 18 skipping to change at page 12, line 6
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.
o The IETF should consider whether to specify more ranges of the o The IETF should consider whether to specify more ranges of the
IPv4 scope-relative address space for static allocation for IPv4 administratively scoped address space for static allocation
applications which should not be routed over the Internet (such as for applications which should not be routed over the Internet
backup software, etc. -- so that these wouldn't need to use global (such as backup software, etc. -- so that these wouldn't need to
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 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, feedback for the preliminary version of this memo. Myung-Ki Shin,
Jerome Durand, and John Kristoff also suggested improvements. Jerome Durand, John Kristoff, and Dave Price 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.
IANA may be interested in reviewing the accuracy of the statement on IANA may be interested in reviewing the accuracy of the statement on
eGLOP address assignments in Section 3.4. eGLOP address assignments in Section 3.4.1.
(RFC-editor: please remove this section at publication.) (RFC-editor: please remove this section at publication.)
7. Security Considerations 7. Security Considerations
This memo only describes different approaches to allocating and This memo only describes different approaches to allocating and
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.
skipping to change at page 13, line 18 skipping to change at page 14, line 7
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-01
(work in progress), March 2005. (work in progress), November 2005.
[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 13, line 51 skipping to change at page 14, line 40
draft-jdurand-ipv6-multicast-ra-00 (work in progress), draft-jdurand-ipv6-multicast-ra-00 (work in progress),
February 2005. February 2005.
[MBONED-IETF59] [MBONED-IETF59]
"MBONED WG session at IETF59", "MBONED WG session at IETF59",
<http://www.ietf.org/proceedings/04mar/172.htm>. <http://www.ietf.org/proceedings/04mar/172.htm>.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997. RFC 2131, March 1997.
[RFC2375] Hinden, R. and S. Deering, "IPv6 Multicast Address
Assignments", RFC 2375, July 1998.
[RFC2608] Guttman, E., Perkins, C., Veizades, J., and M. Day, [RFC2608] Guttman, E., Perkins, C., Veizades, J., and M. Day,
"Service Location Protocol, Version 2", RFC 2608, "Service Location Protocol, Version 2", RFC 2608,
June 1999. June 1999.
[RFC2730] Hanna, S., Patel, B., and M. Shah, "Multicast Address [RFC2730] Hanna, S., Patel, B., and M. Shah, "Multicast Address
Dynamic Client Allocation Protocol (MADCAP)", RFC 2730, Dynamic Client Allocation Protocol (MADCAP)", RFC 2730,
December 1999. December 1999.
[RFC2771] Finlayson, R., "An Abstract API for Multicast Address [RFC2771] Finlayson, R., "An Abstract API for Multicast Address
Allocation", RFC 2771, February 2000. Allocation", RFC 2771, February 2000.
skipping to change at page 15, line 8 skipping to change at page 15, line 44
(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 administraively scoped address space and the
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.
Espoo Espoo
Finland Finland
Email: psavola@funet.fi Email: psavola@funet.fi
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
skipping to change at page 16, line 20 skipping to change at page 17, line 47
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.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
 End of changes. 38 change blocks. 
75 lines changed or deleted 103 lines changed or added

This html diff was produced by rfcdiff 1.29, available from http://www.levkowetz.com/ietf/tools/rfcdiff/