1 LSP-Trace over MPLS tunnels draft-nitinb-lsp-ping-over-mpls-tunnel-00 Nitin BahadurJuniper Networks Kireeti KompellaJuniper Networks IETF 69, MPLS WG, Chicago

2 Tracing a Tunneled LSP ABC E D LDP RSVP 1.Do not allow tracing inside RSVP LSP 2.Allow tracing inside RSVP LSP

3 Problem scenario ABC E D LDP RSVP 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 Solution ABC E D LDP RSVP Intermediate node (router B) provides a FEC stack of 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, 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 ( instead of ) 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 ?