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IETF 67, MPLS WG, San Diego 11/08/2006

P2MP MPLS-TE FRR with P2MP Bypass Tunnel draft-leroux-mpls-p2mp-te-bypass-00.txt J.L. Le Roux (France Telecom) R. Aggarwal (Juniper). IETF 67, MPLS WG, San Diego 11/08/2006. Background 1/2.

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IETF 67, MPLS WG, San Diego 11/08/2006

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  1. P2MP MPLS-TE FRR with P2MP Bypass Tunnel draft-leroux-mpls-p2mp-te-bypass-00.txtJ.L. Le Roux (France Telecom) R. Aggarwal (Juniper) IETF 67, MPLS WG, San Diego 11/08/2006

  2. Background 1/2 • Extensions to detour and facility backup FRR procedures so as to support FRR protection of P2MP TE-LSPs defined in draft-ietf-mpls-p2mp-rsvp-te-p2mp • Facility backup protection only relies on P2P Bypass tunnels • Hence to protect a branch node, several P2P Bypass tunnels are required and the PLR must replicate the traffic • This may lead to significant inefficient bandwidth usage

  3. R1 R2 R5 R4 R3 25 40 45 37 28 22 22 45 IP IP IP IP IP IP IP IP 31 30 45 22 IP IP Background 2/2 P2P Bypass tunnel 30-> pop, R4 31->pop, R5 Protected P2MP TE-LSP Replication • Traffic replicated on shared links • In some networks there may be several tens of LSRs downstream to a protected node on a P2MP LSP • Operational exemples with 30 downstream LSRs… • This may make this solution inapplicable 45-> 28, R6 40 -> 45, R4 22, R5 25 -> 40, R2 FRR -> 30, 45, R3 31, 22, R2 22-> 37, R7

  4. Solution overview • This draft defines extensions to the facility backup FRR procedure so as to support P2MP Bypass tunnels • A P2MP Bypass Tunnel is used to protected a set of P2MP TE-LSPs against branch node failure • A set of P2MP LSPs that traverse the PLR, the protected node and the set of MPs can be protected by the same P2MP Bypass Tunnel • During failure the traffic on a protected P2MP TE-LSP is tunneled within a P2MP bypass tunnel towards the set of MPs thanks to label stacking • Inner label = backup LSP Label, used on the MP to forward traffic to the protected LSP. Outer label = P2MP Bypass tunnel Label • To avoid data replication on the PLR, a same backup LSP label (inner label) is assigned by the PLR to all MPs, following RSVP-TE Upstream Label Assignment procedure (= P2MP MPLS Hierarchy) • draft-ietf-mpls-rsvp-upstream-00.txt

  5. PLR Procedure • To protect a P2MP TE-LSP against branch node failure the PLR selects an appropriate P2MP bypass tunnel • The set of Bypass Leaf LSRs (MP) must allow reaching all leaves downstream to the protected node • The backup P2MP LSP is signaled prior to the failure • The same backup LSP label is assigned by the PLR to all MPs, in the context of the P2MP Bypass Tunnel • For each MP, the PLR sends one or more Path messages including: • One or more S2L sub-LSPs that transit through the MP • An Upstream Assigned Label Object carrying the backup LSP label (inner label) • The Bypass Tunnel session object carried within the IF-ID HOP object • This allows context identification on the MP • Path messages for the backup LSP sent using directed signaling • During failure the PLR reroutes the traffic received on a P2MP TE-LSP within the P2MP Bypass tunnel, with the corresponding backup LSP label

  6. MP Procedure • A backup LSP label is looked up in the context of the underlying P2MP bypass tunnel on which the packet is received • This requires PHP to be deactivated on the P2MP bypass tunnel • The MP maintains a context specific ILM per P2MP bypass tunnel • The MP installs the backup LSP label in the ILM for the corresponding P2MP bypass tunnel • Identified by its session object carried in the IF-ID HOP object • A backup LSP label is mapped to the outgoing interface(s) and label(s) of the corresponding protected P2MP LSP

  7. Path P2MP tunnel P sender R1 sub-lsp to R6 UA Label 50 IF HOP = tunnel B 30-> 21, R4 23, R5 45-> 28, R6 21 -> P2MP Tunnel B ILM 40 -> 45, R4 22, R5 R7 R3 R4 R6 R2 R1 R5 25 -> 40, R2 FRR: 50, 30, R3 45 40 37 28 22 25 IP IP IP IP IP IP Path P2MP tunnel P sender R1 sub-lsp to R7 UA Label 50 IF HOP = tunnel B 21 30 23 50 50 50 IP IP IP 22-> 37, R7 23 -> P2MP Tunnel B ILM Illustration Protected P2MP TE-LSP P2MP Bypass tunnel P2MP tunnel B P2MP tunnel P P2MP tunnel B ILM (label 21) 50 -> 28, R6 P2MP tunnel B ILM (label 23) 50 -> 37, R7

  8. Next Steps • Need to address comments received on the list and offline • A P2MP LSP could be protected using a combination of P2MP bypass tunnels • Useful when there is no overlapping Bypass, Allows reusing existing Bypass • Reduces the number of bypass, but requires replication • Tension between control plane optimization and data plane optimization • Need to discuss backward compatibility with MP that do not support upstream label assignment: Combination of P2MP and P2P Bypass • Support for P2MP bypass whose leaf LSRs are a superset of the protected LSP downstream LSRs • Aggregation that allows significant reduction of the number of bypass LSPs • Counter part: During failure, the traffic is sent to LSRs that are not MP of the protected LSP (they will drop the traffic), again the tension • Define procedures for LAN interface protection • A P2MP Bypass can be used to protect a LAN interface that connects a branch LSR and a set of downstream LSRs

  9. Conclusion • This drafts complements the base P2MP RSVP-TE spec • WG feedback is required • Adopt as WG doc?

  10. ThanksQuestions?

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