draft-ietf-mboned-ssm232-09.txt   rfc4608.txt 
Network Working Group Shepherd Network Working Group D. Meyer
Internet-Draft Cisco Request for Comments: 4608 R. Rockell
Expires: December 16, 2006 Rockell BCP: 120 G. Shepherd
Sprint Category: Best Current Practice August 2006
Meyer
Cisco
June 14, 2006
Source-Specific Protocol Independent Multicast in 232/8 Source-Specific Protocol Independent Multicast in 232/8
draft-ietf-mboned-ssm232-09
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
IP Multicast group addresses in the 232/8 (232.0.0.0 to IP Multicast group addresses in the 232/8 (232.0.0.0 to
232.255.255.255) range are designated as source-specific multicast 232.255.255.255) range are designated as source-specific multicast
destination addresses and are reserved for use by source-specific destination addresses and are reserved for use by source-specific
multicast applications and protocols. This document defines multicast applications and protocols. This document defines
operational recommendations to ensure source-specific behavior within operational recommendations to ensure source-specific behavior within
the 232/8 range. the 232/8 range.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................2
1.1. BCP, Experimental Protocols and Normative References . . . 3 1.1. BCP, Experimental Protocols, and Normative References ......2
2. Operational practices in 232/8 . . . . . . . . . . . . . . . . 4 2. Operational practices in 232/8 ..................................4
2.1. Preventing local sources from sending to shared tree . . . 4 2.1. Preventing Local Sources from Sending to Shared Tree .......4
2.2. Preventing remote sources from being learned/joined 2.2. Preventing Remote Sources from Being Learned/Joined
via MSDP . . . . . . . . . . . . . . . . . . . . . . . . . 5 via MSDP ...................................................4
2.3. Preventing receivers from joining the shared tree . . . . . 5 2.3. Preventing Receivers from Joining the Shared Tree ..........4
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 2.4. Preventing RPs as Candidates for 232/8 .....................5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 3. Acknowledgements ................................................5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations .........................................5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. References ......................................................6
6.1. Normative References . . . . . . . . . . . . . . . . . . . 7 5.1. Normative References .......................................6
6.2. Informative References . . . . . . . . . . . . . . . . . . 7 5.2. Informative References .....................................6
7. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
8. Intellectual Property and Copyright Statements . . . . . . . . . . 9
1. Introduction 1. Introduction
Current PIM Sparse Mode (PIM-SM) [I-D.pim-sm-v2-new] relies on the Current Protocol Independent Multicast - Sparse Mode (PIM-SM)
shared Rendezvous Point (RP) tree to learn about active sources for a [RFC4601] relies on the shared Rendezvous Point (RP) tree to learn
group and to support group-generic (Any Source Multicast or ASM) data about active sources for a group and to support group-generic (Any
distribution. The IP Multicast group address range 232/8 has been Source Multicast or ASM) data distribution. The IP Multicast group
designated for Source-Specific Multicast (SSM) applications and address range 232/8 has been designated for Source-Specific Multicast
protocols [IANA] and SHOULD support source-only trees only, [RFC3569] applications and protocols [IANA] and SHOULD support
precluding the requirement of an RP and a shared tree; active sources source-only trees only, precluding the requirement of an RP and a
in the 232/8 range will be discovered out of band. PIM-SM Designated shared tree; active sources in the 232/8 range will be discovered out
Routers (DR), with local membership, are capable of joining the of band. PIM Sparse Mode Designated Routers (DR) with local
shortest path tree for the source directly using SSM functionality of membership are capable of joining the shortest path tree for the
PIM-SM. source directly using SSM functionality of PIM-SM.
Operational best common practices in the 232/8 group address range Operational best common practices in the 232/8 group address range
are necessary to ensure shortest path source-only trees across are necessary to ensure shortest path source-only trees across
multiple domains in the Internet [RFC3569], and to prevent data from multiple domains in the Internet [RFC3569], and to prevent data from
sources sending to groups in the 232/8 range from arriving via shared sources sending to groups in the 232/8 range from arriving via shared
trees. This avoids unwanted data arrival, and allows several sources trees. This avoids unwanted data arrival and allows several sources
to use the same group address without conflict at the receivers. to use the same group address without conflict at the receivers.
The operational practices SHOULD: o Prevent local sources from The operational practices SHOULD:
sending to shared tree o Prevent receivers from joining the shared
tree o Prevent RP's as candidates for 232/8 o Prevent remote sources
from being learned/joined via MSDP [RFC3618]
1.1. BCP, Experimental Protocols and Normative References o Prevent local sources from sending to shared tree
o Prevent receivers from joining the shared tree
o Prevent RPs as candidates for 232/8
o Prevent remote sources from being learned/joined via Multicast
Source Discovery Protocol (MSDP) [RFC3618]
1.1. BCP, Experimental Protocols, and Normative References
This document describes the best current practice for a widely This document describes the best current practice for a widely
deployed Experimental protocol, MSDP. There is no plan to advance deployed Experimental protocol, MSDP. There is no plan to advance
the MSDP's status (for example, to Proposed Standard). The reasons MSDP's status (for example, to Proposed Standard). The reasons for
for this include: this include:
o MSDP was originally envisioned as a temporary protocol to be o MSDP was originally envisioned as a temporary protocol to be
supplanted by whatever the IDMR working group produced as an supplanted by whatever the Inter-Domain Multicast Routing
inter-domain protocol. However, the IDMR WG (or subsequently, the (IDMR) working group produced as an inter-domain protocol.
BGMP WG) never produced a protocol that could be deployed to However, the IDMR WG (or subsequently, the Border Gateway
replace MSDP. Multicast Protocol (BGMP) WG) never produced a protocol that
could be deployed to replace MSDP.
o One of the primary reasons given for MSDP to be classified as o One of the primary reasons given for MSDP to be classified as
Experimental was that the MSDP Working Group came up with Experimental was that the MSDP Working Group came up with
modifications to the protocol that the WG thought made it better modifications to the protocol that the WG thought made it
but that implementors didn't see any reasons to deploy. Without better but that implementors didn't see any reasons to deploy.
these modifications (e.g., UDP or GRE encapsulation), MSDP can Without these modifications (e.g., UDP or GRE encapsulation),
have negative consequences to initial packets in datagram streams. MSDP can have negative consequences to initial packets in
datagram streams.
o Scalability: Although we don't know what the hard limits might be, o Scalability: Although we don't know what the hard limits might
readvertising everything you know every 60 seconds clearly limits be, readvertising everything you know every 60 seconds clearly
the amount of state you can advertise. limits the amount of state you can advertise.
o MSDP reached near ubiquitous deployment as the de-facto standard o MSDP reached nearly ubiquitous deployment as the de facto
inter-domain multicast protocol in the IPv4 Internet. standard inter-domain multicast protocol in the IPv4 Internet.
o No consensus could be reached regarding the reworking of MSDP to o No consensus could be reached regarding the reworking of MSDP
address the many concerns of various constituencies within the to address the many concerns of various constituencies within
IETF. As a result, a decision was taken to document what is the IETF. As a result, a decision was taken to document what
(ubiquitously) deployed and move that document to Experimental. is (ubiquitously) deployed and to move that document to
While advancement of MSDP to Proposed Standard was considered, for Experimental. Although advancement of MSDP to Proposed
the reasons mentioned above, it was immediately discarded. Standard was considered, for the reasons mentioned above, it
was immediately discarded.
o The advent of source specific multicast and protocols such as bi- o The advent of protocols such as source-specific multicast and
directional PIM, as well as embedded RP techniques for IPv6, have bi-directional PIM, as well as embedded RP techniques for IPv6,
further reduced consensus that a replacement protocol for MSDP for have further reduced consensus that a replacement protocol for
the IPv4 Internet is required. MSDP for the IPv4 Internet is required.
The RFC Editor's policy regarding references is that they be split The RFC Editor's policy regarding references is that they be split
into two categories known as "normative" and "informative". into two categories known as "normative" and "informative".
Normative references specify those documents which must be read to Normative references specify those documents that must be read for
understand or implement the technology in an RFC (or whose technology one to understand or implement the technology in an RFC (or whose
must be present for the technology in the new RFC to work) [RFCED]. technology must be present for the technology in the new RFC to work)
In order to understand this document, one must also understand both [RFCED]. In order to understand this document, one must also
the PIM-SM and MSDP documents. As a result, references to these understand both the PIM [RFC4601] and MSDP [RFC3618] documents. As a
documents are normative. The IETF has adopted the policy that BCPs result, references to these documents are normative.
must not have normative references to Experimental protocols.
However, this document is a special case in that the underlying The IETF has adopted the policy that BCPs must not have normative
Experimental document (MSDP) is not planned to be advanced to references to Experimental protocols. However, this document is a
Proposed Standard. The MBONED Working Group requests approval under special case in that the underlying Experimental document (MSDP) is
the Variance Procedure as documented in RFC 2026 [RFC2026]. Note to not planned to be advanced to Proposed Standard.
RFC-Editor: If IETF/IESG approves this, please change the above
sentence into: The MBONED Working Group has requested approval under The MBONED Working Group requests approval under the Variance
the Variance Procedure as documented in RFC 2026 [RFC2026]. The IESG Procedure as documented in RFC 2026 [RFC2026]. The IESG followed the
followed the Variance Procedure, and after an additional 4 week IETF Variance Procedure and, after an additional 4-week IETF Last Call,
Last Call evaluated the comments and status and has approved this evaluated the comments and status and has approved the document.
document.
The key words "MUST"", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Operational practices in 232/8 2. Operational practices in 232/8
2.1. Preventing local sources from sending to shared tree 2.1. Preventing Local Sources from Sending to Shared Tree
Eliminating the use of shared trees for groups in 232/8, while In order to eliminate the use of shared trees for groups in 232/8,
maintaining coexistence with ASM in PIM-SM, behavior of the RP and/or while maintaining coexistence with ASM in PIM-SM, the behavior of the
the DR needs to be modified. This can be accomplished by RP and/or the DR needs to be modified. This can be accomplished by
o preventing data for 232/8 groups from being sent encapsulated to
the RP by the DR.
o preventing the RP from accepting registers for 232/8 groups from - preventing data for 232/8 groups from being sent encapsulated
the DR. to the RP by the DR,
o preventing the RP from forwarding accepted data down (*,G) tree - preventing the RP from accepting registers for 232/8 groups
for 232/8 groups. from the DR, and
2.2. Preventing remote sources from being learned/joined via MSDP - preventing the RP from forwarding accepted data down (*,G) tree
for 232/8 groups.
2.2. Preventing Remote Sources from Being Learned/Joined via MSDP
SSM does not require active source announcements via MSDP. All SSM does not require active source announcements via MSDP. All
source announcements are received out of band, the the last hop source announcements are received out of band, and the last hop
router being responsible for sending (S,G) joins directly to the router is responsible for sending (S,G) joins directly to the source.
source. To prevent propagation of SAs in the 232/8 range, an RP To prevent propagation of SAs in the 232/8 range, an RP SHOULD
SHOULD
o never originate an SA for any 232/8 groups. - never originate an SA for any 232/8 groups, and
o never accept or forward an SA for any 232/8 groups. - never accept or forward an SA for any 232/8 groups.
2.3. Preventing receivers from joining the shared tree 2.3. Preventing Receivers from Joining the Shared Tree
Local PIM-SM domain practices need to be enforced to prevent local Local PIM domain practices need to be enforced to prevent local
receivers from joining the shared tree for 232/8 groups. This can be receivers from joining the shared tree for 232/8 groups. This can be
accomplished by 232/8 range. accomplished by
o preventing DR from sending (*,G) joins for 232/8 groups. - preventing DR from sending (*,G) joins for 232/8 groups, and
o preventing RP from accepting (*,G) join for 232/8 groups. - preventing RP from accepting (*,G) join for 232/8 groups.
However, within a local PIM-SM domain, any last-hop router NOT However, within a local PIM domain, any last-hop router NOT
preventing (*,G) joins may trigger unwanted (*,G) state toward the RP preventing (*,G) joins may trigger unwanted (*,G) state toward the RP
which intersects an existing (S,G) tree, allowing the receiver on the that intersects an existing (S,G) tree, allowing the receiver on the
shared tree to receive the data, breaking the source-specific shared tree to receive the data, which breaks the source-specific
[RFC3569] service model. It is therefore recommended that ALL [RFC3569] service model. It is therefore recommended that ALL
routers in the domain MUST reject AND never originate (*,G) joins for routers in the domain MUST reject AND never originate (*,G) joins for
232/8 groups. In those cases in which an ISP is offering its 232/8 groups.
customers (or others) the use of the ISP's RP, the ISP SHOULD NOT
allow (*,G) joins in the 232/8 range.
Because SSM does not require a PIM-SM RP, all RPs SHOULD NOT offer In those cases in which an ISP is offering its customers (or others)
the use of the ISP's RP, the ISP SHOULD NOT allow (*,G) joins in the
232/8 range.
2.4. Preventing RPs as Candidates for 232/8
Because SSM does not require an RP, all RPs SHOULD NOT offer
themselves as candidates in the 232/8 range. This can be themselves as candidates in the 232/8 range. This can be
accomplished by accomplished by
o preventing RP/BSR from announcing in the 232/8 range - preventing RP/BSR from announcing in the 232/8 range,
o preventing ALL routers from accepting RP delegations in the 232/8
range
o precluding RP functionality on RP for the 232/8 range - preventing ALL routers from accepting RP delegations in the
232/8 range, and
Note that in typical practice, RP's announce themselves as candidates - precluding RP functionality on RP for the 232/8 range.
Note that in typical practice, RPs announce themselves as candidates
for the 224/4 (which obviously includes 232/8). It is still for the 224/4 (which obviously includes 232/8). It is still
acceptable to allow the advertisement of 224/4 (or any other superset acceptable to allow the advertisement of 224/4 (or any other superset
of 232/8); however, this approach relies on the second point, above, of 232/8); however, this approach relies on the second point, above;
namely, that routers silently just ignore the RP delegation in the namely, that routers silently ignore the RP delegation in the 232/8
232/8 range, and prevent sending or receiving using the shared tree, range and prevent sending or receiving using the shared tree, as
as described previously. Finally, an RP SHOULD NOT be configured as described previously. Finally, an RP SHOULD NOT be configured as a
a candidate RP for 232/8 (or more specific range). candidate RP for 232/8 (or for a more specific range).
3. IANA Considerations 3. Acknowledgements
This document creates no new requirements on IANA namespaces This document is the work of many people in the multicast community,
[RFC2434]. including (but not limited to) Dino Farinacci, John Meylor, John
Zwiebel, Tom Pusateri, Dave Thaler, Toerless Eckert, Leonard
Giuliano, Mike McBride, and Pekka Savola.
4. Security Considerations 4. Security Considerations
This document describes operational practices that introduce no new This document describes operational practices that introduce no new
security issues to PIM-SM in either SSM or ASM operation. However, security issues to PIM-SM [RFC4601] in either or SSM [RFC3569] or ASM
in the event that the operational practices described in this operation.
document are not adhered to, some problems may surface. In
particular, section 2.3 describes the effects of non-compliance of However, in the event that the operational practices described in
last-hop routers (or to some degree, rogue hosts sending PIM-SM this document are not adhered to, some problems may surface. In
messages themselves) on the source-specific service model; creating particular, Section 2.3 describes the effects of non-compliance of
last-hop routers (or, to some degree, rogue hosts sending PIM
messages themselves) on the source-specific service model. Creating
the (*,G) state for source-specific (S,G) could enable a receiver to the (*,G) state for source-specific (S,G) could enable a receiver to
receive data it should not get. This can be mitigated by host-side receive data it should not get. This can be mitigated by host-side
multicast source filtering. multicast source filtering.
5. Acknowledgements 5. References
This document is the work of many people in the multicast community, 5.1. Normative References
including (but not limited to) Dino Farinacci, John Meylor, John
Zwiebel, Tom Pusateri, Dave Thaler, Toerless Eckert, Leonard
Giuliano, Mike McBride, and Pekka Savola.
6. References [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
6.1. Normative References "Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
[I-D.ietf-pim-sm-v2-new] [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Fenner, B., "Protocol Independent Multicast - Sparse Mode Requirement Levels", BCP 14, RFC 2119, March 1997.
(PIM-SM): Protocol Specification (Revised)",
draft-ietf-pim-sm-v2-new-12 (work in progress),
March 2006.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996. 3", BCP 9, RFC 2026, October 1996.
[RFC2028] Hovey, R. and S. Bradner, "The Organizations Involved in [RFC3569] Bhattacharyya, S., "An Overview of Source-Specific
the IETF Standards Process", BCP 11, RFC 2028, Multicast (SSM)", RFC 3569, July 2003.
October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery
Requirement Levels", BCP 14, RFC 2119, March 1997. Protocol (MSDP)", RFC 3618, October 2003.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an 5.2. Informative References
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC3569] Bhattacharyya, S., "An Overview of Source-Specific [IANA] http://www.iana.org
Multicast (SSM)", RFC 3569, July 2003.
[RFC3618] Fenner, B. and D. Meyer, "Multicast Source Discovery [RFCED] http://www.rfc-editor.org/policy.html
Protocol (MSDP)", RFC 3618, October 2003.
6.2. Informative References Authors' Addresses
[IANA] "http://www.iana.org", 2005. David Meyer
7. Authors' Addresses EMail: dmm@1-4-5.net
Robert Rockell
Sprint
EMail: rrockell@sprint.net
Greg Shepherd Greg Shepherd
Cisco Cisco
Email: shep@cisco.com EMail: gjshep@gmail.com
Robert Rockell Full Copyright Statement
Sprint
Email: rrockell@sprint.net Copyright (C) The Internet Society (2006).
Dave Meyer This document is subject to the rights, licenses and restrictions
Cisco contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
Email: dmm@1-4-5.net 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.
8. Intellectual Property Statement 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
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
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 9, line 29 skipping to change at page 7, line 45
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 Acknowledgement
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 (2006). 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
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).
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