--- 1/draft-ietf-mboned-msdp-deploy-05.txt 2006-02-05 00:20:33.000000000 +0100 +++ 2/draft-ietf-mboned-msdp-deploy-06.txt 2006-02-05 00:20:33.000000000 +0100 @@ -1,30 +1,19 @@ INTERNET-DRAFT M. McBride -draft-ietf-msdp-deploy-05.txt J. Meylor + J. Meylor D. Meyer Category Best Current Practice -Expires: July 2004 January 2004 +Expires: September 2004 March 2004 Multicast Source Discovery Protocol (MSDP) Deployment Scenarios - - -Copyright Notice - - Copyright (C) The Internet Society (2004). All Rights Reserved. - - Abstract - - This document describes best current practices for intra-domain and - inter-domain deployment of the Multicast Source Discovery Protocol - (MSDP) in conjunction with Protocol Independent Multicast Sparse Mode - (PIM-SM). + Status of this Document This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. @@ -33,62 +22,71 @@ and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - 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 [RFC 2119]. - This document is a product of the MBONED Working Group. Comments should be addressed to the authors, or the mailing list at mboned@lists.uoregon.edu. +Copyright Notice + + Copyright (C) The Internet Society (2004). All Rights Reserved. + + Abstract + + This document describes best current practices for intra-domain and + inter-domain deployment of the Multicast Source Discovery Protocol + (MSDP) in conjunction with Protocol Independent Multicast Sparse Mode + (PIM-SM). + Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 2. Inter-domain MSDP Peering Scenarios. . . . . . . . . . . . . . 5 - 2.1. Peering between PIM Border Routers. . . . . . . . . . . . . 5 - 2.2. Peering between Non-Border Routers. . . . . . . . . . . . . 6 - 2.3. MSDP Peering without BGP. . . . . . . . . . . . . . . . . . 8 - 2.4. MSDP Peering at a Multicast Exchange. . . . . . . . . . . . 8 - 3. Intra-domain MSDP Peering Scenarios. . . . . . . . . . . . . . 9 - 3.1. Peering between MSDP and MBGP Configured Routers. . . . . . 9 - 3.2. MSDP Peer is not BGP Peer (or no BGP Peer). . . . . . . . . 10 - 3.3. Hierarchical Mesh Groups. . . . . . . . . . . . . . . . . . 11 - 3.4. MSDP and Route Reflectors . . . . . . . . . . . . . . . . . 11 - 3.5. MSDP and Anycast RPs. . . . . . . . . . . . . . . . . . . . 12 - 4. Intellectual Property. . . . . . . . . . . . . . . . . . . . . 13 - 5. Security Considerations. . . . . . . . . . . . . . . . . . . . 13 - 5.1. Filtering SA messages . . . . . . . . . . . . . . . . . . . 14 - 5.2. SA message state limits . . . . . . . . . . . . . . . . . . 14 - 6. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 14 - 7. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 15 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 - 8.1. Normative References. . . . . . . . . . . . . . . . . . . . 16 - 8.2. Informative References. . . . . . . . . . . . . . . . . . . 17 - 9. Author's Addresses . . . . . . . . . . . . . . . . . . . . . . 17 - 10. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 17 + 1.1. BCP, Experimental Protocols and Normative References. . . . 5 + 2. Inter-domain MSDP Peering Scenarios. . . . . . . . . . . . . . 6 + 2.1. Peering between PIM Border Routers. . . . . . . . . . . . . 7 + 2.2. Peering between Non-Border Routers. . . . . . . . . . . . . 8 + 2.3. MSDP Peering without BGP. . . . . . . . . . . . . . . . . . 9 + 2.4. MSDP Peering at a Multicast Exchange. . . . . . . . . . . . 10 + 3. Intra-domain MSDP Peering Scenarios. . . . . . . . . . . . . . 10 + 3.1. Peering between MSDP and MBGP Configured Routers. . . . . . 10 + 3.2. MSDP Peer is not BGP Peer (or no BGP Peer). . . . . . . . . 11 + 3.3. Hierarchical Mesh Groups. . . . . . . . . . . . . . . . . . 12 + 3.4. MSDP and Route Reflectors . . . . . . . . . . . . . . . . . 13 + 3.5. MSDP and Anycast RPs. . . . . . . . . . . . . . . . . . . . 14 + 4. Security Considerations. . . . . . . . . . . . . . . . . . . . 14 + 4.1. Filtering SA messages . . . . . . . . . . . . . . . . . . . 15 + 4.2. SA message state limits . . . . . . . . . . . . . . . . . . 15 + 5. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 15 + 6. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 16 + 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 + 7.1. Normative References. . . . . . . . . . . . . . . . . . . . 17 + 7.2. Informative References. . . . . . . . . . . . . . . . . . . 18 + 8. Author's Addresses . . . . . . . . . . . . . . . . . . . . . . 18 + 9. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 18 + 10. Intellectual Property . . . . . . . . . . . . . . . . . . . . 19 + 11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 19 1. Introduction MSDP [RFC3618] is used primarily in two deployment scenarios: o Between PIM Domains MSDP can be used between Protocol Independent Multicast Sparse - Mode (PIM-SM) [RFC2362] domains to convey information + Mode (PIM-SM) [PIM-SM] domains to convey information about active sources available in other domains. MSDP peering used in such cases is generally one to one peering, and utilizes the deterministic peer-RPF (Reverse Path Forwarding) rules described in the MSDP specification (i.e., does not use mesh-groups). Peerings can be aggregated on a single MSDP peer. Such a peer can typically have from one to hundreds of peerings, which is similar in scale to BGP peerings. o Within a PIM Domain @@ -103,42 +101,110 @@ one-to-one peering with MSDP peers outside that PIM domain for discovery of external sources. MSDP for anycast-RP without external MSDP peering is a valid deployment option and common. Current best practice for MSDP deployment utilizes PIM-SM and the Border Gateway Protocol with multi-protocol extensions (MBGP) [RFC1771, RFC2858]. This document outlines how these protocols work together to provide an intra-domain and inter-domain Any Source Multicast (ASM) service. - Multicast (ASM) service. The PIM-SM specification assumes that SM - operates only in one PIM domain. MSDP is used to enable the use of - multiple PIM domains by distributing the required information about - active multicast sources to other PIM domains. Due to breaking the - Internet multicast infrastructure down to multiple PIM domains, MSDP - also enables the possibility to set policy on the visibility of the - groups and sources. + The PIM-SM specification assumes that SM operates only in one PIM + domain. MSDP is used to enable the use of multiple PIM domains by + distributing the required information about active multicast sources + to other PIM domains. Due to breaking the Internet multicast + infrastructure down to multiple PIM domains, MSDP also enables the + possibility to set policy on the visibility of the groups and + sources. Transit IP providers typically deploy MSDP to be part of the global multicast infrastructure by connecting to their upstream and peer multicast networks using MSDP. Edge multicast networks typically have two choices: to use their Internet providers RP, or to have their own RP and connect it to their ISP using MSDP. By deploying their own RP and MSDP, one can use internal multicast groups which are not visible to the provider's RP. This helps with internal multicast being able to continue to work in the event there is a problem with connectivity to the provider or the provider's RP/MSDP is experiencing difficulties. In the simplest cases where no internal multicast groups are necessary, there is often no need to deploy MSDP. +1.1. BCP, Experimental Protocols and Normative References + + This document describes the best current practice for a widely + deployed Experimental protocol, MSDP. There is no plan to advance the + MSDP's status (for example, to Proposed Standard). The reasons for + this include: + + o MSDP was originally envisioned as a temporary protocol to be + supplanted by whatever the IDMR working group produced as an + inter-domain protocol. However, the IDMR WG (or subsequently, + the 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 + Experimental was that the MSDP Working Group came up with + modifications to the protocol that the WG thought made it + better but that implementors didn't see any reasons to + deploy. Without these modifications (e.g., UDP or GRE + encapsulation), MSDP can have negative consequences to initial + packets in datagram streams. + + o Scalability: Although we don't know what the hard limits might + be, readvertising everything you know every 60 seconds clearly + limits the amount of state you can advertise. + + o MSDP reached near ubiquitous deployment as the de-facto + standard inter-domain multicast protocol in the IPv4 Internet. + + o No consensus could be reached regarding the reworking of MSDP + to address the many concerns of various constituencies within + the IETF. As a result, a decision was taken to document what is + (ubiquitously) deployed and move that document to Experimental. + While advancement of MSDP to Proposed Standard was considered, + for the reasons mentioned above, it was immediately discarded. + + o The advent of protocols such as source specific multicast and + bi-directional PIM, as well as embedded RP techniques for + IPv6, have further reduced consensus that a replacement + protocol for MSDP for the IPv4 Internet is required. + + The RFC Editor's policy regarding references is that they be split + into two categories known as "normative" and "informative". Normative + references specify those documents which must be read to understand + or implement the technology in an RFC (or whose technology must be + present for the technology in the new RFC to work) [RFCED]. In order + to understand this document, one must also understand both the PIM + and MSDP documents. As a result, references to these documents are + normative. + + The IETF has adopted the policy that BCPs must not have normative + references to Experimental protocols. However, this document is a + special case in that the underlying Experimental document (MSDP) is + not planned to be advanced to Proposed Standard. + + The MBONED Working Group requests approval under the Variance + Procedure as documented in RFC 2026 [RFC2026]. + + Note to RFC-Editor: If IETF/IESG approves this, please change the + above sentence into: The MBONED Working Group has requested approval + under the Variance Procedure as documented in RFC 2026 [RFC2026]. + The IESG followed the Variance Procedure, and after an additional 4 + week IETF Last Call evaluated the comments and status and has + approved this 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 [RFC 2119]. + 2. Inter-domain MSDP Peering Scenarios The following sections describe the most common inter-domain MSDP peering possibilities and their deployment options. 2.1. Peering between PIM Border Routers In this case, the MSDP peers within the domain have their own RP located within a bounded PIM domain. In addition, the domain will typically have its own Autonomous System (AS) number and one or more @@ -464,112 +528,91 @@ address either through Auto-RP, BSR, or a static RP assignment. Each designated router in the domain will send source registers and group joins to the Anycast RP address. Unicast routing will direct those registers and joins to the nearest Anycast RP. If a particular Anycast RP router fails, unicast routing will direct subsequent registers and joins to the nearest Anycast RP. That RP will then forward an MSDP update to all peers within the Anycast MSDP mesh group. Each RP will then forward (or receive) the SAs to (from) external customers and providers. -4. Intellectual Property - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. Information on the - IETF's procedures with respect to rights in standards-track and - standards-related documentation can be found in BCP-11. Copies of - claims of rights made available for publication and any assurances of - licenses to be made available, or the result of an attempt made to - obtain a general license or permission for the use of such - proprietary rights by implementors or users of this specification can - be obtained from the IETF Secretariat. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights which may cover technology that may be required to practice - this standard. Please address the information to the IETF Executive - Director. - -5. Security Considerations +4. Security Considerations An MSDP service should be secured by explicitly controlling the state which is created by, and passed within, the MSDP service. As with unicast routing state, MSDP state should be controlled locally, at the edge origination points. Selective filtering at the multicast service edge helps ensure that only intended sources result in SA message creation, and this control helps to reduce the likelihood of state-aggregation related problems in the core. There are a variety of points where local policy should be applied to the MSDP service. -5.1. Filtering SA messages +4.1. Filtering SA messages The process of originating SA messages should be filtered to ensure only intended local sources are resulting in SA message origination. In addition, MSDP speakers should filter on which SA messages get received and forwarded. Typically there is a fair amount of (S,G) state in a PIM-SM domain that is local to the domain. However, without proper filtering, sa- messages containing these local (S,G) announcements may be advertised to the global MSDP infrastructure. Examples of this includes domain local applications that use global IP multicast addresses and sources that use RFC 1918 addresses [RFC1918]. To improve on the scalability of MSDP and to avoid global visibility of domain local (S,G) information, an external SA filter list is recommended to help prevent unnecessary creation, forwarding, and caching of well-known domain local sources. -5.2. SA message state limits +4.2. SA message state limits Proper filtering on SA message origination, receipt, and forwarding will significantly reduce the likelihood of unintended and unexpected - spikes in MSDP state However, a sa-cache state limit SHOULD BE + spikes in MSDP state However, a sa-cache state limit SHOULD be configured as a final safeguard to state spikes. When an MSDP peering has reached a stable state (i.e., when the peering has been established and the initial SA state has been transferred), it may also be desirable to configure a rate limiter for the creation of new SA state entries. -6. IANA Considerations +5. IANA Considerations - This document creates a no new requirements on IANA namespaces + This document creates no new requirements on IANA namespaces [RFC2434]. -7. Acknowledgments +6. Acknowledgments The authors would like to thank Pekka Savola, John Zwiebel, Swapna Yelamanchi, Greg Shepherd, and Jay Ford for their feedback on earlier versions of this document. -8. References +7. References -8.1. Normative References +7.1. Normative References + + [PIM-SM] Fenner, B., et. al, "Protocol Independent Multicast - + Sparse Mode (PIM-SM): Protocol Specification + (Revised)", draft-ietf-pim-sm-v2-new-09.txt. Work + in progress. [RFC1771] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995. [RFC1918] Y. Rekhter, R. Moskowitz, D. Karrenberg, G. de Groot, E. Lear, "Address Allocation for Private Internets", RFC 1918, Feburary, 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels" RFC 2119/BCP 14, March 1997. - [RFC2362] D. Estrin, et. al., "Protocol Independent - Multicast - Sparse Mode (PIM-SM): Protocol - Specification", RFC 2362, June, 1998. - [RFC2365] Meyer, D. "Administratively Scoped IP Multicast", RFC 2365, July, 1998. [RFC2434] Narten, T., and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 2434/BCP 0026, October, 1998. [RFC2858] Bates T., Y. Rekhter, R. Chandra, D. Katz, "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000. @@ -579,49 +622,53 @@ [RFC3446] Kim, D., et. al., "Anycast Rendezvous Point (RP) Mechanism using Protocol Independent Multicast (PIM) and Multicast Source Discovery Protocol (MSDP)", RFC 3446, January, 2003. [RFC3618] Meyer, D. and W. Fenner (Editors), "The Multicast Source Discovery Protocol (MSDP)", RFC 3618, October, 2003. -8.2. Informative References +7.2. Informative References [AUTORP] Fenner, W., et. al., " Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", draft-ietf-pim-sm-v2-new-08.txt, April, 2004. Work in progress. [BSR] Fenner, W., et. al., "Bootstrap Router (BSR) Mechanism for PIM Sparse Mode", draft-ietf-pim-sm-bsr-03.txt, February, 2003. Work in progress. [IANA] http://www.iana.org -9. Author's Addresses + [RFCED] http://www.rfc-editor.org/policy.html#policy.refs + +8. Author's Addresses Mike McBride Cisco Systems Email: mcbride@cisco.com John Meylor Cisco Systems Email: jmeylor@cisco.com David Meyer Email: dmm@1-4-5.net -10. Full Copyright Statement +9. Full Copyright Statement - Copyright (C) The Internet Society (2004). All Rights Reserved. + Copyright (C) The Internet Society (2004). 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 translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of @@ -632,10 +679,39 @@ The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS 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. + +10. Intellectual Property + + The IETF takes no position regarding the validity or scope of any + Intellectual Property Rights or other rights that might be claimed to + pertain to the implementation or use of the technology described in + 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 + made any independent effort to identify any such rights. Information + on the procedures with respect to rights in RFC documents can be + found in BCP 78 and BCP 79. + + Copies of IPR disclosures made to the IETF Secretariat and any + assurances of licenses to be made available, or the result of an + attempt made to obtain a general license or permission for the use of + such proprietary rights by implementers or users of this + specification can be obtained from the IETF on-line IPR repository at + http://www.ietf.org/ipr. + + The IETF invites any interested party to bring to its attention any + copyrights, patents or patent applications, or other proprietary + rights that may cover technology that may be required to implement + this standard. Please address the information to the IETF at ietf- + ipr@ietf.org. + +11. Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society.