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LSP-Trace over MPLS tunnels

LSP-Trace over MPLS tunnels. draft-nitinb-lsp-ping-over-mpls-tunnel-01 Nitin Bahadur Juniper Networks Kireeti Kompella Juniper Networks George Swallow Cisco Systems IETF 70, MPLS WG, Vancouver. E. A. B. C. D. RSVP. RSVP. LDP. LDP. LDP. Tracing a hierarchical 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-01 Nitin Bahadur Juniper Networks Kireeti Kompella Juniper Networks George Swallow Cisco Systems IETF 70, MPLS WG, Vancouver

  2. E A B C D RSVP RSVP LDP LDP LDP Tracing a hierarchical LSP • Options available at node B: • Do not allow tracing inside RSVP LSP • Allow tracing inside RSVP LSP

  3. A B C D E RSVP RSVP LDP LDP LDP Problem scenario (1): Tracing a hierarchical LSP • Node B’s “effective” next-hop for LDP LSP is node D • However the “real” next-hop is node C • Node A sends echo request with LDP FEC to node C • Node C knows nothing about LDP FEC, so cannot perform FEC validation. • Node A cannot tell why it is getting a response from node C

  4. E A B C D RSVP RSVP LDP LDP LDP Solution • Intermediate node (router B) provides a PUSH FEC stack tlv containing <RSVP> in DSMAP of echo response • Ingress (router A) pushes RSVP onto it’s 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 • Implicitly conveys that RSVP LSP is over -- pop it • Ingress (router A) now pops an entry from (local) FEC stack and resends echo request to router D with LDP FEC

  5. A B C D E F LDP LDP eBGP RSVP RSVP Problem Scenario (II): Tracing a stitched LSP No current mechanism to perform end-to-end trace of stitched LSPs. Current trace mechanisms will only trace till router C.

  6. A B C D E F LDP LDP eBGP RSVP RSVP Solution • Intermediate node (router C) provides a POP FEC stack sub-tlv (LDP) and PUSH FEC stack sub-tlv (eBGP) in DSMAP of echo response. • Ingress (router A) performs the corresponding stitch operation and sends eBGP FEC in next echo request (to router D) • Router D provides a POP FEC stack tlv (eBGP) and PUSH FEC stack sub-tlv (RSVP) in DSMAP of echo response. • Ingress (router A) performs the corresponding stitch operation and sends RSVP FEC in next echo request (to router E) • Router F responds with EGRESS_OK for the end-to-end LSP.

  7. Solution concept • Intermediate routers provide ingress information regarding: • start of a new tunnel • end of a tunnel • tunnel stitch. • FEC details can be hidden by sending a NIL FEC, instead of actual FEC being pushed. • Analogous to push/pop operations in the data-plane. • Main logic at ingress application to correctly traverse the tunnels

  8. TLV changes proposed … • Builds on RFC 4379 (LSP-Ping) • Downstream Mapping TLV deprecated • Not extensible: can’t have sub-TLVs (blame Kireeti!) • Not easy to associate new information in echo response • Downstream detailed mapping TLV introduced • Similar to previous one • Contains sub-TLVs to represent all variable length things • New sub-TLVs can be added in future to associate things with DSMAP. • Procedures outlined to deal with old and new TLV formats.

  9. Downstream Detailed Mapping TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MTU | Address Type | DS Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Downstream IP Address (4 or 16 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Downstream Interface Address (4 or 16 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sub-tlv length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + + List of Sub TLVs + + + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  10. DDMAP Sub-TLVs Multipath Sub-TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Multipath Type| Multipath Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | (Multipath Information) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Label-stack Sub-TLV 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Downstream Label | Protocol | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Downstream Label | Protocol | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  11. DDMAP Sub-TLVs (contd.) Stack change sub-TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Operation Type| Address type| FEC-tlv length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote Peer Address (0, 4 or 16 octets | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . FEC TLV . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Operation Type # Operation ----------------------- --------- 1 Push 2 Pop

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

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