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 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 l Facility backup protection only relies on P2P Bypass tunnels l Hence to protect a branch node, several P2P Bypass tunnels are required and the PLR must replicate the traffic l This may lead to significant inefficient bandwidth usage

Background 2/2 l Traffic replicated on shared links l In some networks there may be several tens of LSRs downstream to a protected node on a P2MP LSP è Operational exemples with 30 downstream LSRs… l This may make this solution inapplicable R1R1 R2R2 R5R5 R4R4 R3R3 Protected P2MP TE-LSP P2P Bypass tunnel 40 -> 45, R4 22, R5 25 -> 40, R2 FRR -> 30, 45, R3 31, 22, R2 30-> pop, R4 31->pop, R5 IP 25 IP 45 IP 22 IP 28 IP 37 IP 40 IP > 28, R6 22-> 37, R7 IP 2231 IP 45 IP 22 Replication

Solution overview l This draft defines extensions to the facility backup FRR procedure so as to support P2MP Bypass tunnels l A P2MP Bypass Tunnel is used to protected a set of P2MP TE-LSPs against branch node failure è 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 l 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 è Inner label = backup LSP Label, used on the MP to forward traffic to the protected LSP. Outer label = P2MP Bypass tunnel Label l 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) è draft-ietf-mpls-rsvp-upstream-00.txt

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

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

Illustration R1R1 R2R2 R5R5 R4R4 R3R3 Protected P2MP TE-LSP P2MP Bypass tunnel IP 25 IP 22 IP 28 IP 37 IP 40 IP 5030 IP 45 R6R6 R7R7 P2MP tunnel B P2MP tunnel P Path P2MP tunnel P sender R1 sub-lsp to R6 UA Label 50 IF HOP = tunnel B Path P2MP tunnel P sender R1 sub-lsp to R7 UA Label 50 IF HOP = tunnel B 40 -> 45, R4 22, R5 25 -> 40, R2 FRR: 50, 30, R3 30-> 21, R4 23, R5 45-> 28, R6 21 -> P2MP Tunnel B ILM 22-> 37, R7 23 -> P2MP Tunnel B ILM P2MP tunnel B ILM (label 21) 50 -> 28, R6 P2MP tunnel B ILM (label 23) 50 -> 37, R7 IP 5021 IP 5023

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

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

Thanks Questions?