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BGP based Virtual Private Multicast Service Auto-Discovery and

Signaling

draft-raggarwa-l2vpn-p2mp-pw-02.txt

R. Aggarwal (Juniper)

Y. Kamite (NTT)

F. Jounay (France Telecom)

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Motivation What is a P2MP PW?

Virtual Private Multicast Service (VPMS)

VPMS Auto-Discovery

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What is a P2MP PW ? A Point-to-Multipoint (P2MP) Pseudo Wire

(PW) is a mechanism that emulates the essential attributes of a unidirectional P2MP Telecommunications service such as P2MP ATM over a Packet Switched Network (PSN).

Chartered in PWE3 WG

• draft-ietf-pwe3-p2mp-pw-requirements

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Virtual Private Multicast Service (VPMS)

One applicability of P2MP PWs is to deliver a Layer 2 multicast service, that carries multicast frames (encoded using Layer 2 or IP mechanisms) from a multicast source to one or more multicast receivers.

P2MP PWs enable a L2VPN to provide a Virtual Private P2MP unidirectional service (VPMS), which may be in addition to the Virtual Private Wire Service (VPWS) offered by the L2VPN.

Chartered in L2VPN WG

• draft-ietf-l2vpn-vpms-frmwk-requirements-00

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VPMS Auto-discovery Auto-discovery (A-D) is required as per Virtual Private

Multicast Service (VPMS) requirements

• “Framework and Requirements for Virtual Private Multicast Service (VPMS)", draft-ietf-l2vpn-vpms-frmwk-requirements

Draft-raggarwa-l2vpn-p2mp-pw-02.txt describes procedures for BGP based VPMS A-D

• These procedures are meant to apply to both BGP and LDP as P2MP PW signaling protocols

• Procedures in the draft are fully specified only for BGP as the P2MP PW signaling protocol at this point

Draft-raggarwa-l2vpn-p2mp-pw-02.txt also describes BGP based procedures for P2MP PW signaling for VPMS that may be used when BGP is used for VPMS A-D

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Historical Context of the Draft Comparison with draft-raggarwa-l2vpn-p2mp-pw-

00.txt and draft-raggarwa-l2vpn-p2mp-pw-00.txt

• Version 0/1 specified VPMS service definition• Now specified in draft-ietf-l2vpn-vpms-frmw

requirements

• Version 0/1 specified P2MP PW encapsulation and forwarding

• Now specified in draft-raggarwa-pwe3-p2mp-pw-encaps

• Version 0/1 specified BGP based VPMS A-D and P2MP PW signaling

• Retained in draft-raggarwa-l2vpn-p2mp-pw-02.txt

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Layer 2 Multicast VPN A L2VPN that offers VPMS is referred to as a L2 Multicast VPN

A L2 MVPN is defined by two sets of sites, Sender Sites set and Receiver Sites set, with the following properties:

• CEs within the Sender Sites set could originate traffic for CEs in the Receiver Sites set. A PE delivers traffic received from a CE in the Sender Sites set to the CEs in the Receiver Sites set using a P2MP PW.

• CEs not in the Receiver Sites set should not be able to receive this traffic.

• CEs within the Receiver Sites set could receive traffic originated by any CEs in the Sender Sites set.

• CEs within the Receiver Sites set should not be able to receive traffic originated by any CE that is not in the Sender Sites set.

A L2 MVPN is determined by a set of administrative policies that define the sender sites and receiver sites and these policies could be implemented using Route Targets

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Auto-Discovery (A-D) Auto-discovery procedures for the PEs in the Receiver Sites set to

discover the PEs (and CEs) in the Sender Sites Set.

Depending on the P2MP PSN signaling technology the PEs in the Sender Sites set may have to discover the PEs in the Receiver Sites set

This draft uses procedures in draft-ietf-l2vpn-vpls-mcast for A-D

• BGP NLRI: <RD, CE ID>

• MUST carry the set of Route Targets being exported by the VPMS instance

.

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Discovering Sender Sites and Receiver Sites

Whether a CE belongs to a sender site or a receiver site is determined from the Route Targets (RT) that are configured to enforce the administrative policies of a L2 MVPN.

These RTs are advertised in the corresponding BGP A-D routes.

For instance if some of the sites in a VPMS are only in sender site set while others are only in receiver sites set, then

• CEs that are in the receiver site set are configured to import only sender site set RTs.

• CEs that are in the sender site set are configured to import only the receiver site set RTs.

• In this case two RTs are required to provision the VPMS instance.

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Redundancy draft-ietf-l2vpn-vpms-frmw requirements specifies

redundancy requirements that require multi-homing a sender CE to two or more PEs

• Ingress PE redundancy BGP based A-D allows multi-homing a CE to two or more

PEs

• If the CE ID is the same on all the multi-homed PEs, BGP path selection ensures that only a single PE is chosen as the primary PE at a time

It’s a matter of policy whether

• More than one ingress PEs send traffic on the P2MP PWs that they are the root of and the egress PEs drop the duplicate copies

• Only the primary ingress PE sends traffic on the P2MP PW that it is the root of

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Signaling L2 MVPN requires signaling procedures for the root

PE to signal P2MP PWs to leaf PEs. P2MP PSN tunnels carry the P2MP PW traffic

• With a P2MP PW demultiplexor that can be used to identify individual root CEs and enables carrying traffic for multiple P2MP PWs (which may belong to different L2VPNs) over the same P2MP PSN tunnel.

• Using upstream assigned MPLS label as the P2MP PW de-multiplexor.

• Draft-raggarwa-pwe3-p2mp-pw-encaps

P2MP PW de-multiplexor is signaled using mechanisms described in draft-ietf-l2vpn-vpls-mcast

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Inter-AS and Multi-Segment P2MP PWs

Following applies only to P2MP PWs signaled using BGP

Inter-AS optons (a), (b) and (c) that are described in VPLS-MCAST are supported

A Multi-Segment P2MP PW is equivalent to a segmented inter-AS tree that is described in [VPLS-MCAST], for inter-AS option (b).

• In VPLS-MCAST a segmented inter-AS tree for a particular VPLS instance is formed by dynamically stitching intra-AS segments.

• A segment of an inter-AS segmented tree is equivalent to a segment of a Multi-Segment P2MP PW.

Procedures that are used in VPLS-MCAST for segmented inter-AS trees are re-used to dynamically stitch segments of a Multi- Segment P2MP PW.