Support for Downstream Mapping Information

To validate the downstream mapping for an LSP, a node sending a DSMAP TLV must include the incoming and (optionally) outgoing IF_Num values for the interfaces that it expects the LSP to transit. Additionally, it includes the out-label for the LSP in the Label TLV for the DSMAP in the echo request message.

The incoming and outgoing if-num values correspond to the incoming and outgoing interfaces transited by an LSP at the next hop LER and LSR are configured using the dsmap command, as follows:

config
   router
      mpls
         lsp
            working-tp-path
               mep
                 dsmap <in-if-num>[:<out-if-num>]

config
   router
      mpls
         lsp
            protect-tp-path
               mep
                  dsmap <in-if-num>[:<out-if-num>]


config
   router
      mpls
         mpls-tp
            transit-path
               forward-path
                  mip
                     dsmap <in-if-num>[:<out-if-num>]
                     exit
                reverse-path
                   mip
                      dsmap <in-if-num>[:<out-if-num>]
                      exit

A node sending a DSMAP TLV includes these in-if-num and out-if-num (if configured) values. Additionally, it includes the out-label for the LSP in the Label TLV for the DSMAP in the echo request message.