Internet Engineering Task Force G. Shepherd INTERNET-DRAFT Cisco Systems draft-shepherd-ssm232-00.txt E. Luczycki Broadcast.com R. Rockell Sprintlink March, 2000 Expires September 2000 Source-Specific Protocol Independent Multicast in 232/8 Status of this Memo 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. Internet Drafts are draft documents valid for a maximum of six months. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as a "working draft" or "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. Distribution of this document is unlimited. Abstract IP Multicast group addresses in the 232/8 (232.0.0.0 to 232.255.255.255) range are designated as source-specific multicast [SSM] destination addresses and are reserved for use by source- specific applications and protocols [IANA-ALLOCATION]. This document defines operational recommendations to ensure source- specific behavior within the 232/8 range. Shepherd Expires September 2000 [Page 1]
Internet Draft draft-shepherd-ssm232-00.txt March, 2000 1. Introduction Current PIM Sparse Mode [PIM-SM] relies on the shared Rendezvous Point (RP) tree to learn about active sources for a group and to support group-generic (not source specific) data distribution. The IP Multicast group address range 232/8 has been designated for source-specific [SSM] applications and protocols [IANA-ALLOCATION] and should support source- only trees only, precluding the requirement of an RP and a shared tree; active sources in the 232/8 range will be discovered out of band. The PIM Sparse Mode [PIM-SM] Designated Routers (DR), with local membership, are capable of joining the shortest path tree for the source directly using Source-Specific PIM [PIM-SS]. Operational best common practices in the 232/8 group address range are necessary to ensure shortest path source-only trees across multiple domains in the Internet [PIM-SO], and to prevent data from sources sending to groups in the 232/8 range from arriving via shared trees. This avoids unwanted data arrival, and allows several sources to use the same group address without conflict at the receivers. The operational practices should o Prevent local sources from sending to shared tree o Prevent remote sources from being learned/joined via MSDP o Prevent receivers from joining the shared tree o Prevent RP's as candidates for 232/8 2. Operational practices in 232/8 2.1. Preventing local sources from sending to shared tree Eliminatng the use of shared trees for groups in 232/8, while mainaining coexistance with PIM-SM, behavior of the RP and/or the DR needs to be modified. This can be accomplished by - preventing data for 232/8 groups from being sent encapsulated to the RP by the DR - preventing the RP from accepting registers for 232/8 groups from the DR - preventing the RP from forwarding accepted data down (*,G) tree 2.2. Preventing remote sources from being learned/joined via MSDP PIM-SS does not require active source announcements via MSDP. All source Shepherd Expires September 2000 [Page 2]
Internet Draft draft-shepherd-ssm232-00.txt March, 2000 announcements are received out of band, the the last hop router is responsible for sending (S,G) joins directly to the source. To prevent propagation of SAs in the 232/8 range, an RP should - never originate 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 Local PIM domain practices need to be enforced to prevent local receivers from joining the shared tree for 232/8 groups. This can be accomplished by - preventing DR from sending (*,G) joins - preventing RP from accepting (*,G) join 2.4. Preventing RP's as candidates for 232/8 Because PIM-SS does not require an RP, all RPs SHOULD NOT offer themselves as candidates in the 232/8 range. This can be accomplished by - preventing RP/BSR from announcing in the 232/8 range - preventing DRs from accepting deligations in this range - precluding RP functionality on RP for the 232/8 range 3. References IANA-ALLOCATION Internet Assigned Numbers Authority, http://www.isi.edu/in- notes/iana/assignments/multicast-addresses. SSM Holbrook, H., Cain, B., "Source-Specific Multicast for IP (SSM)", draft-holbrook-ssm-00.txt, September, 2000. PIM-SMD. Estrin, et. al., "Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification", RFC 2362, June, 1998 PIM-SSBhaskar, N., "Source-Specific Protocol Independent Multicast (PIM-SS)", draft-bhaskar-pim-ss-00.txt, March, 2000. PIM-SODiot, C., Giuliano, L., Rockell, R., "Deployment of PIM-SO at Sprint (PIM-SO)", draft-bhattach-diot-PIMSO-00.txt, March, 2000. Shepherd Expires September 2000 [Page 3]
Internet Draft draft-shepherd-ssm232-00.txt March, 2000 MSDP Farinacci, D., et. al. "Multicast Source Discovery Protocol (MSDP)", draft-ietf-msdp-spec-05.txt, February, 2000. 4. Author's Addresses Greg Shepherd Cisco Systems 170 Tasman Drive San Jose, CA, 95134 Phone: +1 541 912 9758 Email: shep@cisco.com Ed Luczycki Broadcast.com eds@yahoo-inc.com Robert Rockell Sprint Internet Service Center Reston, Virginia rrockell@sprintlink.net