1. Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net 1 Multicast in BGP/MPLS VPNs and VPLS draft-raggarwa-l3vpn-mvpn-vpls-mcast- 01.txt Rahul Aggarwal rahul@juniper.net

2. 2 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Authors  Rahul Aggarwal (Juniper)  Thomas Morin (France Telecom)  Luyuan Fang (AT&T)  Yakov Rekhter (Juniper)  Anil Lohiya (Juniper)  Tom Pusateri (Juniper)  Lenny Giuliano (Juniper)  Chaitanya Kodeboniya (Juniper)

3. 3 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Agenda  IP Multicast in VPLS – Issues with existing proposals  Design Objective  Solution

4. 4 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net IP Multicast in VPLS  This talk is about IP multicast data traffic in VPLS  It is not about VPLS control traffic  It is also not about flooding to all PEs (by the ingress PE) in the VPLS for unknown destinations for unicast traffic

5. 5 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Current VPLS proposals:  “ Virtual Private LAN Service” ( draft-ietf-l2vpn-vpls- bgp-02.txt )  “ Virtual Private LAN Services over MPLS ” ( draft-ietf- l2vpn-vpls-ldp-05.txt )  Limitations of these solutions for IP multicast in VPLS…

6. 6 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net VPLS Reference Model PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPLS A Site 2 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPLS B Site 1 VPLS B Site 2 VPLS A Site 4 Emulated LAN for VPLS B VPLS B Site 3 VSI-A VSI-B Emulated LAN for VPLS A VPLS A Site 3 VPLS A Site 1 VSI – Virtual Switch Instance No PIM peering between CEs and PEs No PIM peering among PEs

7. 7 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Forwarding VPLS multicast traffic within the service provider – Emulated LAN  Ingress replication of the IP multicast packet for a given VPLS by the ingress PE  The packet is sent over the Emulated LAN associated with the VPLS  Emulated LAN is realized by ingress replication – use collection of the existing (unicast) LSPs From ingress PE to egress PEs No additional state (beyond what is require by unicast) on P routers May result in sending multiple copies of the same multicast packet over a given service provider link

8. 8 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Emulated LAN Ingress Replication: example PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPLS A Site 3 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPLS B Site 1 VPLS B Site 2 VPLS B Site 3 VSI-A VSI-B VPLS A Site 2 VPLS A Site 1 Links S1  G1 G1 (S1, G1) traffic to Site 2 (S1, G1) traffic to Site 3 The same (multicast) packet traverses link 3 times VPLS A Site 4 VSI- A G1 (S1, G1) traffic to Site 4

9. 9 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Sending multicast traffic to sites with no receivers: example PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPLS A Site 3 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPLS B Site 1 VPLS B Site 2 VPLS B Site 3 VSI-A VSI-B VPLS A Site 2 VPLS A Site 1 Links S1  G1 G1 (S1, G1) traffic to Site 2 (S1, G1) traffic to Site 3 VPLS A Site 4 VSI- A (S1, G1) traffic to Site 4 Multicast traffic for VPLS A extends to CE-A4, even though it has no receivers for G1 Site 4 has no receivers for G1

10. 10 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Sending multicast traffic to sites with no receivers  As long as PE does not keep track of IP multicast receivers within each site of a given VPLS, PE has to send IP multicast traffic to all the sites within that VPLS  As long as the ingress PE sends (multicast) traffic to all the sites within a VPLS, it is possible that the traffic will be delivered to the sites of that VPLS that have no receivers for the traffic  Suboptimal use of the service provider bandwidth due to sending IP multicast traffic to sites with no receivers is further compounded by the use of ingress replication for Emulated LAN

11. 11 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net How to avoid sending multicast traffic to sites with no receivers – PIM/IGMP snooping  Well-known approach used by Ethernet switches An Ethernet switch determines whether a particular port has receivers for a given (S,G) by snooping on the PIM/IGMP messages received over that port Requires to disable PIM Join suppression  In the context of VPLS, PE has to snoop on PIM/IGMP messages received from: all sites of that VPLS (directly) connected to the PE, Can not be avoided AND all the remote PEs that have members of that VPLS Huge overhead particularly given the periodic nature of PIM Joins  Just like with Ethernet switches, PIM/IGMP snooping in the context of VPLS requires to disable PIM Join suppression by VPLS customers

12. 12 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net PIM snooping : example PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPLS A Site 3 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPLS B Site 1 VPLS B Site 2 VPLS B Site 3 VSI-A VSI-B VPLS A Site 2 VPLS A Site 1 Links S1  G1 G1 (S1, G1) traffic to Site 2 (S1, G1) traffic to Site 3 VSI- A PE1 does not send (S1,G1) traffic to Site 4, as PE1 notices that Site 4 has no receivers for G1 PIM Join (S1, G1) from Site 2 PIM Join (S1, G1) from Site 3 VPLS A Site 4 Site 4 has no receivers for G1

13. 13 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Multicast in 2547 VPNs vs multicast in VPLS  Focus on minimizing service provider bandwidth usage by (a) minimizing the amount of (multicast) traffic replication within the service provider, and by (b) avoiding sending traffic to the PE routers with no receivers At the expense of additional state within the service provider  Focus on minimizing state in the service provider routers by eliminating any multicast-related state in the P routers At the expense of additional bandwidth usage within the service provider Why the tradeoffs for multicast in 2547 VPNs are NOT the same as the tradeoffs for multicast in VPLS ? 2547 VPNs: VPLS:

14. 14 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Solution  The existing solutions are clearly not sufficient for IP multicast support in VPLS  Draft-raggarwa-l3vpn-mvpn-vpls-mcast-00.txt Work in progress Aims to overcome the issues that have been pointed out  A scalable MVPN/VPLS multicast architecture Overcomes issues with prior solutions This presentation talks only about VPLS  Reuse procedures across MVPN/VPLS multicast as much as possible

15. 15 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net VPLS IP Multicast Avoid Flooding  IGMP/PIM snooping between PE and directly connected sites Not performed for remote sites  Convert periodic PIM C-Joins snooped from a directly connected CE to reliable protocol messages across the SP core Eliminates the overhead of snooping periodic PIM messages from remote sites This can be done using either PIM or BGP Draft points out the information elements  The C-Join/Prune has to be sent to all the PEs in the VPLS if the PE sending the C-Join/Prune does not know the route to the C-Source A database of C-Source to the PE that the C-source is behind needs to be maintained to eliminate this overhead

16. 16 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net VPLS IP Multicast Data Plane  Flexible/Scalable Transport of Customer Multicast Data Packets through the SP core  SP Multicast Trees Allow multiple VPLSs to share a single SP multicast tree Can be set up using PIM or P2MP MPLS TE LSPs or another P2MP technology  Ingress Replication Has its applicability

17. 17 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Aggregate Trees  Allow one SP multicast Tree to be shared across multiple VPLSs  Can be setup using PIM-SM or PIM-SSM or P2MP MPLS TE or another P2MP technology  Requires an inner label to demultiplex a particular VPLS ‘Upstream’ label allocation by the root of the tree  A flexible tool to reduce state in the SP network  State in the SP network doesn’t grow proportional to the number of VPLSs Similar to unicast in VPLS or unicast in 2547

18. 18 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Aggregate Trees…  Use BGP signaling  Mapping of an Aggregate Tree to VPLSs associated with the Tree are signaled by the root using BGP Leaves of the tree are PEs belonging to all the VPLSs mapped to the tree: discovered using the auto-discovery mechanism (eg. BGP) Applicable to both BGP and LDP based VPLS  The draft points out the information elements to be exchanged  Encoding open to discussion

19. 19 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Aggregate Trees: Example PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPLS A Site 3 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPLS B Site 1 VPLS B Site 2 VPLS B Site 3 VSI-A VSI-B VPLS A Site 2 VPLS A Site 1 Links S1  G1 G1 The same (multicast) packet traverses the link only once VPLS A Site 4 VSI- A G1 Aggregate Tree for VPLS A and VPLS B Upstream label for VPLS A Upstream label for VPLS B

20. 20 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Aggregate Data Trees  A flexible tool to create separate trees for a set of customer groups to avoid flooding  Allow one SP multicast Tree to be shared across multiple (C- S,C-Gs) that may belong to different VPLSs Leaves of the tree are (C-S, C-Gs) discovered from the C- Join information  Setup using BGP signaling by the root Applicable to both LDP and BGP based VPLS  Requires an inner label to de-multiplex a particular VPLS ‘Upstream’ label allocation by the root of the tree

21. 21 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net On P2MP MPLS TE  Certainly applicable to setting up SP multicast tree Potential TE benefits  Aggregate Tree and Aggregate Data Trees  Procedures in the draft are independent of the SP P2MP technology and apply to P2MP MPLS TE as well

22. 22 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Conclusion  Solution aims to overcome the limitations of IP multicast in VPLS with existing solutions  VPLS portion to be moved to a separate draft  WG Feedback ?