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LSP-Trace over MPLS tunnels

LSP-Trace over MPLS tunnels. draft-nitinb-lsp-ping-over-mpls-tunnel-00 Nitin Bahadur Juniper Networks Kireeti Kompella Juniper Networks IETF 69, MPLS WG, Chicago. E. A. B. C. D. RSVP. RSVP. LDP. LDP. LDP. Tracing a Tunneled LSP. Do not allow tracing inside RSVP LSP

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LSP-Trace over MPLS tunnels

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  1. LSP-Trace over MPLS tunnels draft-nitinb-lsp-ping-over-mpls-tunnel-00 Nitin Bahadur Juniper Networks Kireeti Kompella Juniper Networks IETF 69, MPLS WG, Chicago

  2. E A B C D RSVP RSVP LDP LDP LDP Tracing a Tunneled LSP • Do not allow tracing inside RSVP LSP • Allow tracing inside RSVP LSP

  3. E A B C D RSVP RSVP LDP LDP LDP Problem scenario Allow tracing inside RSVP LSP • Node B’s next-hop for LDP LSP is node C • Node A sends echo request with LDP FEC to node C • Node C knows nothing about LDP FEC, returns error • Node A reports trace error

  4. Problem Statement • For hierarchical LSPs or LSPs tunneled over other LSPs, we should be able to trace the entire end-to-end path. • Intermediate outer-LSP nodes should allow inner LSP trace to go through • Intermediate outer-LSP nodes not required to provide detailed information about outer LSP

  5. E A B C D RSVP RSVP LDP LDP LDP Solution • Intermediate node (router B) provides a FEC stack of <RSVP, LDP> in echo response • Ingress (router A) uses that FEC stack in echo request when sending next echo request (to router C) • When router D receives echo request with FEC stack containing <RSVP, LDP>, it sends Egress-Ok for RSVP FEC • Ingress (router A) now pops an entry from (local) FEC stack and resends echo request to router D with LDP FEC

  6. Solution (contd.) • Intermediate routers provide ingress information regarding start of a new tunnel. • FEC details can be hidden by sending a NIL FEC in response (<NIL, LDP> instead of <RSVP, LDP>) • Main logic at ingress application to correctly traverse the tunnels

  7. TLV changes proposed by draft • Builds on RFC 4379 (LSP-Ping) • Intermediate routers that are ingress of a new tunnel/LSP-segment modify the echo response as follows: • Add a bit in DSMAP to indicate more data is associated with DSMAP • A new Downstream FEC stack TLV is added • Contains information to associate with particular DSMAP • Contains FEC stack (similar to that in echo request) for tracing downstream

  8. Next Steps • WG feedback on problem/solution • Adopt as WG doc ?

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