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BGP based Multi-homing in VPLS IETF-75

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Presentation on theme: "BGP based Multi-homing in VPLS IETF-75"— Presentation transcript:

1 BGP based Multi-homing in VPLS IETF-75
Bhupesh Kothari Kireeti Kompella Wim Henderickx Florin Balus

2 Status draft-kothari-henderickx-l2vpn-vpls-multihoming-01.txt
Common BGP based multi-homing procedures for LDP and BGP signaled VPLS Draft is based on: draft-kompella-l2vpn-vpls-multihoming-02.txt draft-henderickx-l2vpn-vpls-multihoming-00.txt

3 Outline Provisioning Model Multi-homing NLRI
Designated Forwarder Election Multi-AS VPLS MAC Flush

4 Background: BGP VPLS PW infrastructure is created based on VE-IDs (RFC 4761) VE-ID=2 BGP VPLS PE2 A C VE-ID=1 PE1 PE3 B VE-ID=3 Single VE-ID on PE1 is sufficient for customer sites A and B VE-ID is assigned per VPLS instance irrespective of ACs (no customer site attached to PE3)

5 Background: LDP VPLS PW infrastructure is created based on procedures defined in RFC 4762 LDP VPLS PE2 A C PE1 PE3 B PWs can be created either using FEC-128 or FEC-129 Procedures defined in this draft for LDP signaled VPLS do not depend on use of BGP Auto-discovery

6 Provisioning Model Multi-homing Identifier (MH-ID): Same MH-ID must be configured on PEs connected to the same customer site MH-ID=10 VPLS PE3 B PE1 Customer site A dual-homed to PE devices for redundancy PE4 A PE2 C MH-ID=10

7 Multi-homing NLRI VPLS Use of NLRI defined in RFC 4761
VE-ID field in the NLRI is set to MH-ID LB, OFF and LR are set to zero MH-ID=10 VPLS PE3 B PE1 PE4 A PE2 C MH-ID=10 MH-ID is not used to create PWs

8 Designated Forwarder Election
Based on DF tie-breaking rules, PE1 is DF PE1: MH-ID=10, PREF=200 VPLS PE1 PE3 B Based on DF election, PE3 can chose to not send traffic to PE2 (depends on whether there are additional sites on PE2 or not) A PE2 AC is put in non-forwarding state PE2: MH-ID=10, PREF=100 PE2 loses DF election; elected as non-DF

9 Multi-AS Procedures For the tie-breaker, the loopback of the PE originating the MH NLRI is needed This may be overwritten in a multi-AS environment (such as in option B) To preserve this, we use the Route Origin Extended Community

10 Multi-AS Procedures Local Pref is not passed across ASes
Again, this is needed for tie-breaking To solve this, the “VPLS Preference” field in the L2 info community is used Compatibility between LP and VPLS Pref is described in the document

11 Multi-AS Procedures For both BGP and LDP signaling, there are three models for inter-AS operation “option A”: direct, back-to-back connections between ASes, with each AS treating the other as a CE device “option B”: ASBRs mediating the VPLS “option C”: multi-hop eBGP connections between RRs in each AS This is completely analogous to IP VPNs

12 MAC Flush If the designated forwarder (PE1) for a multi-homed CE goes down, remote PEs (PE3) should flush the MACs they learned from PE1 Ideally, this is done implicitly However, if PE3 is not upgraded, it may not flush; thus, in some cases, PE1 may have to send an explicit flush to the remote PEs

13 Next Steps Propose to adopt this as WG document?

14 Questions/Comments?


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