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Copyright © 2004 Juniper Networks, Inc. Proprietary and 1 Multicast in BGP/MPLS VPNs and VPLS draft-raggarwa-l3vpn-mvpn-vpls-mcast

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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 [email protected] Slide 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) Slide 3 3 Copyright 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Agenda IP Multicast in VPLS Issues with existing proposals Design Objective Solution Slide 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 Slide 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 Slide 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 Slide 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 Slide 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 Slide 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 Slide 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 Slide 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 Slide 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 Slide 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: Slide 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 Slide 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 Slide 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 Slide 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 doesnt grow proportional to the number of VPLSs Similar to unicast in VPLS or unicast in 2547 Slide 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 Slide 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 Slide 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 Slide 21 21 Copyright 2004 Juniper Networks,

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