Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net 1 Multicast in BGP/MPLS VPNs draft-to-become-l3vpn-2547bis-mcast- 00.txt Eric Rosen Rahul Aggarwal

2 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Other Authors/Contributors  Co-Authors Yiqun Cai, IJsbrands Wijnands, Yakov Rekhter, Thomas Morin  Contributors/Acknowledgements Arjen Boers, Toerless Eckert, Luyuan Fang, Dino Farinacci, Lenny Guiliano, Anil Lohiya, Tom Pusateri, Ted Qian, Robert Raszuk, Tony Speakman, Dan Tappan, Authors of draft- yasukawa-l3vpn-p2mp-mcast-00.txt

3 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Agenda  Design Objective  Overview of the MVPN Architecture  MVPN Auto-Discovery  MVPN Routing Information Exchange  I-PMSI Instantiation  S-PMSI Instantiation  Inter-AS Procedures  Co-locating C-RP on the PE  Encapsulation

4 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Multicast Support for 2547 VPN: components  Control plane: exchanging VPN multicast routing information: Between CE and PE Among PEs  Data plane: forwarding VPN multicast traffic within the service provider(s) Very similar to the unicast support for 2547 VPNs

5 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Design Objectives for multicast support in 2547 VPN service (not a complete list)  A given customer (multicast) packet should traverse a given service provider link at most once  Deliver customer multicast traffic to only PEs that have (customer) receivers for that traffic  Deliver customer multicast traffic along the “optimal” paths within the service provider (from the ingress PE to the egress PEs) The amount of state within the service provider network required to support Multicast in 2547 VPN service should be no greater than what is required to support unicast in 2547 VPN service The overhead of maintaining the state to support Multicast in 2547 VPN service should be no greater than what is required to support unicast in 2547 VPN service Optimize Bandwidth: Optimize State: Optimizing Bandwidth and State are conflicting goals

6 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Agenda  Design Objective  Overview of the MVPN Architecture  MVPN Auto-Discovery  MVPN Routing Information Exchange  I-PMSI Instantiation  S-PMSI Instantiation  Inter-AS Procedures  Co-locating C-RP on the PE  Encapsulation

7 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net MVPN Architecture Control Plane  MVPN Auto-Discovery Allows discovering MVPN membership information using BGP Elimination of overhead of PIM Hellos  MVPN Routing Information Exchange among PEs Preserves the ability to use existing PIM machinery Allows reliable exchange of VPN Multicast Routing Information PIM refresh reduction or BGP  Control traffic doesn’t necessarily use the tunnels used by the data traffic Similar to 2547 unicast architecture Allows unicast PIM or BGP

8 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net MVPN Architecture Data Plane Ingress Replication Separate Tree for Every C-(S, G) Separate Tree per-set-of MVPNs “Inclusive Mapping” Separate Tree per-set-of C-(S, G)s “Selective Mapping” Increasing P-router state and Bandwidth efficiency State = Unicast 2547bis Unbounded State Aggregate State Tree = PIM-SM, PIM-SSM, PIM-Bidir, RSVP-TE P2MP LSPs, Receiver Initiated P2MP LSPs Decreasing P-router state and Bandwidth efficiency

9 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net New Framework and Terminology  Prior proposals differ in following ways: multicast service expected from SP network method of implementing the multicast service method of exchanging multicast routing info  One size doesn’t fit all, so need way of describing various options Distinguish multicast service from implementation Clarify relation between routing info exchange and multicast data transport service Clarify inter-relationships of various options

10 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net P-Multicast Service Interface  PMSI: Provider-network Multicast Service Interface  Service is scoped to one MVPN  Three types: MI-PMSI: Multipoint Inclusive, all→all all PEs can transmit to all PEs UI-PMSI: Unidirectional Inclusive, some→all Unidirectional, selected PEs can transmit to selected PEs Selective: S-PMSI, some→some Unidirectional, selected PEs can transmit to selected PEs

11 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Instantiating PMSIs  PMSIs instantiated by tunnels. Possible tunnels: PIM-created trees (any flavor) Point-to-Multipoint LSPs Unicast tunnels: from ingress to all egresses, with ingress replication to root of distribution tree  PMSI instantiation may require set of tunnels  Single tunnel may instantiate more than one PMSI  Encaps a function of tunnel, not service

12 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Mappings to Old Terminology  Default MDT MI-PMSI, instantiated by PIM Shared Tree or set of PIM Source Trees  Data MDT S-PMSI, instantiated by PIM Source Tree  New terminology helpful in: Describing the complete set of options Allowing multiple instantiations of same service, without changing service spec

13 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Tunnel Issues  Applicability of each technique? One size doesn’t fit all MPLS vs. GRE vs. MPLS-in-GRE vs. … Source-initiated or receiver-initiated creation  Options for creating and destroying the tunnels: As part of the discovery phase As separate phase after discovery As needed (depending on traffic characteristics)  Ensuring interoperability? Force common tunnel choice?

14 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Agenda  Design Objective  Overview of the MVPN Architecture  MVPN Auto-Discovery  MVPN Routing Information Exchange  I-PMSI Instantiation  S-PMSI Instantiation  Inter-AS Procedures  Co-locating C-RP on the PE  Encapsulation

15 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Discovery What MVPN multicast-specific info needs to be known before MVPN service can be set up: What PMSIs are going to be used: Will MVPN routing information be unicast or multicast Do we want to have the service available before it is needed What tunnels are to be used to instantiate the PMSIs: What information is needed to set up the tunnels and identify the tunnels What encapsulation is going to be used Is aggregation supported

16 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Agenda  Design Objective  Overview of the MVPN Architecture  MVPN Auto-Discovery  MVPN Routing Information Exchange  I-PMSI Instantiation  S-PMSI Instantiation  Inter-AS Procedures  Co-locating C-RP on the PE  Encapsulation

17 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Exchange of VPN Multicast Routing Info Among PEs  Only two possibilities considered: PIM BGP

18 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Exchange of VPN Multicast Routing Info Among PEs: PIM  C-Join/Prune messages can be either: Multicast (requires MI-PMSI) Unicast (from one PE to one PE) N.B.: Unicast is different from MI-PMSI over unicast tunnels Can use full or lightweight adjacency

19 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Using PIM…  Lightweight adjacencies Minimizes overhead by eliminating periodic messages: Refresh reduction (to be spec’ed by PIM WG) Hello suppression (in L3VPN, BGP provides the necessary information) Not interoperable with full adjacencies  Finding the RPF in inter-AS MVPNs

20 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Using PIM  Control Messages: Multicast or Unicast MI-PMSI: Allows Asserts, Join Suppression, standard “PIM on a LAN” Unicast: no join suppression, no asserts Various Pros and Cons to each Unicast presupposes that all PEs must choose same PE as RPF hop for given C-S

21 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net MVPN Routing Information Exchange Using BGP PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPN A Site 3 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPN B Site 1 VPN B Site 2 VPN A Site 4 VPN B Site 3 VRF-A VRF-B VPN A Site 2 VPN A Site 1 VRF-A RR PEs have I-BGP Peering Only With the RR C-S -> C-G PIM C-Join C-S, C-G BGP MVPN Routing Information Update: <RD, C-S, C-G, Originator PE – PE1 Upstream PE – PE2, RT>

22 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Agenda  Design Objective  Overview of the MVPN Architecture  MVPN Auto-Discovery  MVPN Routing Information Exchange  I-PMSI Instantiation  S-PMSI Instantiation  Inter-AS Procedures  Co-locating C-RP on the PE  Encapsulation

23 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net I-PMSI Instantiation  UI-PMSI or MI-PMSI  Ingress Replication  P-Multicast Trees No architectural limitations on the tree building protocol Current spec limits specific procedures to PIM-SM, PIM-SSM, PIM-Bidir, RSVP-TE P2MP LSPs Source Based Trees or Shared Trees Aggregation  Tunnel Identifier (Usage Described Later) for RSVP-TE P2MP LSPs for PIM-SSM

24 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net PMSI Instantiation Ingress Replication PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPN A Site 3 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPN B Site 1 VPN B Site 2 VPN A Site 4 VPN B Site 3 VRF-A VRF-B VPN A Site 2 VPN A Site 1 VRF-A RR MVPN Membership Discovery: <Ingress Replication Capability, Downstream MPLS Label> eg PE1 C-S -> C-G PIM C-Join C-S, C-G MVPN Rtng Information – Unicast PIM or BGP Ingress Replication – Flooding (S-PMSI Recommended)

25 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Aggregate P-Multicast Trees  Allow one P-multicast Tree to be shared across multiple VPNs  Can be setup using PIM-SM or PIM-SSM or P2MP MPLS TE Support for PIM-Bidir is for further study  Requires a MPLS label to demultiplex a particular VPN ‘Upstream’ label allocation by the root of the tree Egress PEs maintain a separate label space for each P- multicast tree root  State grows less than linearly with number of MVPNs Some efficiency of multicast routing may be sacrificed

26 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net I-PMSI Instantiation P-Multicast Trees PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPN A Site 3 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPN B Site 1 VPN B Site 2 VPN A Site 4 VPN B Site 3 VRF-A VRF-B VPN A Site 2 VPN A Site 1 VRF-A RR MVPN Membership Discovery: eg PE1 C-S -> C-G PIM C-Join C-S, C-G Aggregate Tree – PE2 as Root BGP Signaled MVPN – Tree Binding:

27 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Agenda  Design Objective  Overview of the MVPN Architecture  MVPN Auto-Discovery  MVPN Routing Information Exchange  I-PMSI Instantiation  S-PMSI Instantiation  Inter-AS Procedures  Co-locating C-RP on the PE  Encapsulation

28 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net S-PMSI Instantiation  Separate tree for set of s that may belong to different MVPNs  Increase bandwidth efficiency for the mapped s. Eg. High Bandwidth Streams  Discover the leaves i.e. PEs with receivers in s using MVPN Routing Information For RSVP-TE P2MP LSPs or/and Aggregation Unicast PIM or BGP or MI-PMSI with Join Suppression off  Ingress Replication or P-Multicast Trees  Protocol for switching to S-PMSI BGP or UDP

29 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net S-PMSI Instantiation P-Multicast Trees – BGP Signaling PE 1 CE-B2 CE-B3 PE 3 PE 2 PE 4 VPN A Site 3 CE -A1 CE-B1 CE-A2 CE-A4 CE-A3 VPN B Site 1 VPN B Site 2 VPN A Site 4 VPN B Site 3 VRF-A VRF-B VPN A Site 2 VPN A Site 1 VRF-A RR Leaf Discovery – MVPN Routing Exchange Eg. BGP C-S1 -> C-G1 PIM C-Join C-S2, C-G2 Selective Aggregate Tree – PE2 as Root BGP Signaled set of – Tree Binding: C-S2 -> C-G2 PIM C-Join C-S1, C-G1

30 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net S-PMSIs – UDP Signaling  If an MI-PMSI is in use for flow’s MVPN, can use “in-band” protocol, i.e., UDP-based protocol identifying flow and S- PMSI  Existing protocol may benefit from some enhancements: Reduce soft state overhead Ability to identify non-PIM tunnels

31 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Inter-AS Procedures  First Model – Tunnel spans multiple ASs Support for Unicast VPN Option A, B and C “RPF Attribute” to get around Next-Hop Rewrite in Option B PIM Extension to carry the proxy address when PIM P-Multicast Trees are used and P routers don’t have the route to the ingress PE  Second Model – Each AS can have its own tunneling mechanism for intra-AS tunnels Overlay Inter-AS tunnel on top of the intra-AS tunnels Build on BGP MVPN Auto-discovery and BGP MVPN-Tunnel Binding Support for Unicast VPN Option A, B and C

32 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Inter-AS Procedures Second Model – Overlay Inter-AS Tunnel  MVPN membership spanning tree rooted at the origin AS, with other ASs as nodes of the tree  The overlay tunnel traverses this spanning tree  Origin AS announces that it has a MVPN to other ASs – not the PEs that belong to the MVPN  Each AS node on the spanning tree has its own intra-AS tunnel  MVPN-tunnel binding flows towards the root of the overlay tree using BGP – essentially MPLS label switching at the ASBRs  Support for S-PMSIs

33 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Co-locating C-RP on a PE  One potential deployment model  Customer may outsource C-RP to the SP and the SP may co-locate the C-RP with the PE  Two options: 1. Anycast RP based on (*, G) advertisements that PE receives from CEs This is similar to the model in draft-yasukawa-l3vpn-mvpn-p2mp-00.txt 2. Anycast RP based on propagating active source announcements in BGP This is the model in draft-yasukawa-l3vpn-mvpn-p2mp-00.txt

34 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Encapsulation  When multiple PMSIs are aggregated into a single tunnel, how to demux the packets Unicast Tunnels: MPLS Label (downstream-assigned) Don’t want separate IP dest addr per PE per MVPN Multicast Tunnels: MPLS Label (upstream-assigned)  When PIM messages are unicast: MPLS downstream-assigned label RD (or RT) in PIM message  Ensuring agreement (among PEs) on encaps

35 Copyright © 2004 Juniper Networks, Inc. Proprietary and Confidentialwww.juniper.net Conclusion  Comments ?  Request to be a WG document Request authors of draft-yasukawa-l3vpn-mvpn- p2mp to join the draft