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Source Specific Multicast (SSM) Solutions Aug./2000

Source Specific Multicast (SSM) Solutions Aug./2000. Agenda. Current Status of PIM-SM, MSDP, IGMP New stuff: Source Specific Solutions IGMPv3/PIM-SSM Interim features Roadmap. PIM Sparse Mode Review. Link. Data. Control. A. B. D. RP. C. E.

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Source Specific Multicast (SSM) Solutions Aug./2000

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  1. Source Specific Multicast (SSM) SolutionsAug./2000

  2. Agenda • Current Status of PIM-SM, MSDP, IGMP • New stuff: Source Specific Solutions • IGMPv3/PIM-SSM • Interim features • Roadmap

  3. PIM Sparse Mode Review Link Data Control A B D RP C E The Rendevous Point (RP) is the shared root, and is administratively assigned.

  4. PIM Sparse Mode Review Receiver 1 Joins Group GC Creates (*, G) State, Sends(*, G) Join to the RP A B D RP Join C E Receiver 1

  5. PIM Sparse Mode Review RP Creates (*, G) State A B D RP C E Receiver 1

  6. PIM Sparse Mode Review Source 1 Sends DataA Sends Registers to the RP Source 1 Register A B D RP C E Receiver 1

  7. PIM Sparse Mode Review RP De-Encapsulates RegistersForwards Data Down the Shared TreeSends Joins Towards the Source Source Join Join A B D RP C E Receiver 1 Receiver 2

  8. PIM Sparse Mode Review RP Sends Register-Stop OnceData Arrives Natively Source Register-Stop A B D RP C E Receiver 1

  9. PIM Sparse Mode Review Shared tree rooted at the RP Question: What if this is suboptimal path? Source A B D RP C E Receiver 1

  10. PIM Sparse Mode Review Source Answer: Switch over to shortest path tree. A B D RP (S, G) Join C E Receiver 1

  11. PIM Sparse Mode Review Source Shortest path tree rooted at the source. A B D RP C E Receiver 1

  12. PIM Sparse Mode Review NOTE: RP still important ! Required to support sources which arrive later or are not known by application. Source A B D RP Source 2 C E RP also: - announces active sources via MSDP - identifies group modality - serves as root for bidir Receiver 1

  13. MSDP Overview RP RP RP RP RP r SA Join (*, 224.2.2.2) SA SA SA SA SA SA Message192.1.1.1, 224.2.2.2 s SA Message192.1.1.1, 224.2.2.2 Register 192.1.1.1, 224.2.2.2 MSDP Example Domain E MSDP Peers Source ActiveMessages SA Domain C Domain B Domain D Domain A

  14. MSDP Overview RP RP RP RP RP r Join (S, 224.2.2.2) s MSDP Example Domain E MSDP Peers Domain C Domain B Domain D Domain A

  15. MSDP Overview RP RP RP RP RP Multicast Traffic r s MSDP Example Domain E MSDP Peers Domain C Domain B Domain D Domain A

  16. MSDP Overview RP RP RP RP RP Multicast Traffic r Join (S, 224.2.2.2) s MSDP Example Domain E MSDP Peers Domain C Domain B Domain D Domain A

  17. MSDP Overview RP RP RP RP RP Multicast Traffic r s MSDP Example Domain E MSDP Peers Domain C Domain B Domain D Domain A

  18. What if source is well-known? • Simplify solution for well-known sources, particularly in cases where there is a single source sending to a given group. • Allow immediate use of shortest forwarding path to a specific source, without need to create shared tree. • Eliminate dependence on MSDP for finding sources. • Simplify address allocation for global, single source groups when combined with elimination of shared trees (232/8).

  19. SSM Objective Data Flow r r r s Join source, Get content on shortest path Domain E Join Domain C Domain B Domain D Domain A

  20. Source Specific Multicast • Allows first-hop router to respond to receiver initiated join requests for specific sources within a group. • Allows first-hop router to send s,g join directly to source without creation of shared tree. • Support elimination of shared tree state in 232/8, simplifying address allocation.

  21. Source Specific Multicast • Long term solution: • IGMPv3 in routers and hosts • Allows for inclusions lists and exclusion lists • PIM-SSM • Sends immediate PIM S,G joins based on include lists • Prevents *,G joins from being sent • Interim solutions: • Achieve SSM functionality when IGMPv3 not yet deployed.

  22. IGMPv2 H3 Report for 232.1.2.3 2nd S,G join(s) 1st *,G join Host sends IGMPv2 report for group DR sends *,G join to RP (it has to, it doesn’t know the sources) DR sends S,G join to source (data provides the sources) 1.1.1.10 1.1.1.11 1.1.1.12 H2 H3 H1 1.1.1.1 rtr-a DR adds membership

  23. IGMPv3 H3 Report for 232.1.2.3 source_list S,G join(s) Host sends IGMPv3 report for group which can specify a list of sources to explicity include. IPMulticastListen (Socket, IF, G, INCLUDE, source-list) DR sends S,G join directly to sources in the source_list, and is not required to send *,G join to RP (and must not in 232/8). 1.1.1.10 1.1.1.11 1.1.1.12 H2 H3 H1 1.1.1.1 rtr-a DR adds membership.

  24. PIM Source Specific Mode Host learns of source, group/port First-hop learns of source, group/port First-hop send PIM s,g join directly A B D RP (S, G) Join (S, G) report C E Source Out-of-band source directory, example: web server Receiver 1

  25. PIM Source Specific Mode Source Result: Shortest path tree rooted at the source, with no shared tree. A B D RP C E Receiver 1

  26. Effect of shared trees • Can’t control traffic on shared tree • Can’t avoid address collisions

  27. Eliminating Shared Trees *,G Source C Source B Source A RP Join Data *,G forwarding trees Receiver 1 Want: source A, G, but can only ask for: *,G

  28. Eliminating Shared Trees Source C Source B Source A RP *,G Join Data With data arrival we know “S” so DR can now send S,G join. Receiver 1

  29. Eliminating Shared Trees sa-message registers Source C Source B Source A RP *,G Finally, shortest path but with *,G forwarding trees: Still could get packets from unintended sources: - Source B: registers - Source C: sa-messages Receiver 1

  30. Eliminating Shared Trees Source C Source B sa-message C Source A RP *,G A B registers How to eliminate *,G A: Don’t create *,G using pim-SSM B. Filter registers C. Filter sa-messages Receiver 1

  31. Eliminating Shared Trees Problem: Must specify what group SSM applies to globally. Solution: 232/8 has been allocated by IANA. In this range: • Config PIM-SSM code, include at least 232/8: • prevents *,G • Config pre-PIM-SSM code: • filter registers for sources in 232/8 • filter sa-messages for sources in 232/8

  32. Eliminating shared trees in 232/8 • Control access of 232/8 source data to legacy shared trees by filtering register messages. ip pim accept-register list <acl> | route-map <map> • Control is per source and/or per group. • Prevent origination or forwarding of sa-messages so 232/8 sources cannot send to external receivers. • Accept register AND sa-filters ip msdp sa-filter out|in ...

  33. So where is IGMPv3 ? • IGMPv3 - currently an IETF draft • draft-ietf-idmr-igmp-v3-04.txt (NOTE: Up for last call now) • Most multicast host/router vendors doing initial implementations: • cisco: IGMPv3 implementation commited. • Full IGMPv3 host stacks and apps are in initial implementation phase now. • FreeBSD, LINUX • MIM, vic/vat : What about windows apps?

  34. Source Specific Multicast • Interim solution: IGMPv3-lite • Utilizes simple daemon so application can send v3 messages with source include info directly to router. Daemon available for win95/98/00, MacOS • Interim solution: URD URL RenDezvous • Requires no changes to host stack or apps. • First-hop router intercepts S,G info from http redirect sent by content provider’s web page.

  35. How to Get There What cisco is doing: • IGMPv3/v3-lite/URD and PIM-SSM • 12.1(4)T now, 12.1E and 12.0S soon. • Some IGMPv3 host-side work in-house • IP/TV v3/v3-lite capable client • Extensive work with stack/apps vendors. • Extending field test program • several ISPs and content providers RUNNING LIVE TESTS TODAY!

  36. How to Get There What needs to be done: • Deployment of PIM-SM/SSM multicast • Config 232/8 filtering when PIM-SM • Deployment of IGMPv3 on DR’s • IGMPv3 capable stacks, applications • v3-lite or URD when IGMPv3 not available • Source content • 232/8 (source specific only), and non-232/8 • Further develop web based elements

  37. IETF Documents New SSM WG IDMR WG Combined PIM-SM/SSM PIM WG MBONED WG Framework draft-bhattach-pim-ssm-00.txt PIM SSM Arch IGMPv3 draft-holbrook-ssm-arch.00.txt draft-ietf-idmr-igmp-v3-04.txt draft-holbrook-idmr-igmpv3-ssm-00.txt draft-ietf-pim-sm-v2-new-00.txt 232/8 BCP Ref API draft-shep-ssm232-00.txt draft-ietf-idmr-msf-api-00.txt

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