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RSVP Setup Protection draft-shen-mpls-rsvp-setup-protection-00

Yimin Shen (Juniper Networks) Yuji Kamite (NTT Communication) IETF 83, Paris, France. RSVP Setup Protection draft-shen-mpls-rsvp-setup-protection-00. Overview. What is setup protection? A mechanism that protects LSPs during initial Path message signaling time.

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RSVP Setup Protection draft-shen-mpls-rsvp-setup-protection-00

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  1. Yimin Shen (Juniper Networks) Yuji Kamite (NTT Communication) IETF 83, Paris, France RSVP Setup Protectiondraft-shen-mpls-rsvp-setup-protection-00

  2. Overview What is setup protection? • A mechanism that protects LSPs during initial Path message signaling time. • Based on RSVP facility-backup fast reroute. Why setup protection? • To improve the chances of establishment for LSPs whose explicit paths (EROs) are: • Pre-computed; • Statically configured; • Computed based on a topology that may not reflect the state of every link/node in the network.

  3. RSVP Fast Reroute Establishment: • Signaling of protected LSP • Path message signals the desired path (ERO). • Resv message distributes labels and records route (RRO). • Setting up of local protection on each router • Next-hop address and label (Resv RRO). • Next-next-hop address and label (Resv RRO). Observation: • Local protection can only be established after the protected LSP has been set up.

  4. Problem Description 1. Path (dest = PE2, ERO = i1, i2, i3) What will happen, if there is a link/node failure along the path when the initial Path message is being signaled? Typical behavior today: • RSVP sends PathErr. • IGP floods update-to-date TE info. • Ingress router computes a new path around the failure, and signals the new path. • Existing bypass LSP is ignored. 2. PathErr 3. Path (dest = PE2, ERO = i1, i4, i2, i3) 6. Path i1 i2 i3 P 2 P 0 P 1 P 3 4. Path 5. Path i4 P 3 bypass LSP P 4

  5. Problem Description (cont.) Issues: • If the desired path is pre-computed or fixed, an alternative path may not be possible. • Control plane convergence and path re-computation may introduce a significant delay, which can impact LSP signaling performance. • Existing bypass LSP will not be used, even if it is the preferred alternative path.

  6. Setup Protection PLR (point of local repair) reroutes LSP through an existing bypass LSP. • Detects downstream link/node failure based on strict ERO. • Searches for an existing bypass LSP that is protecting the failed link/node. • Signals a backup LSP through the bypass LSP, using “sender template specific” method. MP (merge point) terminates the backup LSP, and re-creates the protected LSP. Two new LSP Attribute TLVs are defined: • Protected LSP Sender IPv4 Address TLV. • Protected LSP Sender IPv6 Address TLV. • Carried by the LSP_REQUIRED_ATTRIBUTES of Path message of the backup LSP. • Used by MP for recreating the protected LSP. 1. Path (dest = PE2, ERO = i1, i2, i3) 6. Resv 3. Path i1 i2 i3 P 2 MP 4. Resv P 0 P 1 PLR P 3 5. Resv 2. Path i4 P 3 bypass LSP P 4

  7. Setup Protection (cont.) The LSP appears as if it was originally set up along the desired path and failed over to the bypass LSP. • PLR sends Resv with “local protection available” and “local protection in use” in RRO. • PLR sends PathErr of “tunnel locally repaired”. PLR may perform local reversion after the failed link/node is restored. protected LSP protected LSP i1 i2 i3 P 2 MP P 0 P 1 PLR P 3 Backup LSP P 3 i4 bypass LSP P 4

  8. Next Steps • Questions and comments? • WG adoption?

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