Description

This article provides information on how to identify labels that are associated with a specific MPLS LSP.

Symptoms

How to identify labels that are associated with a specific MPLS LSP.

Solution


This article can be very helpful, when troubleshooting MPLS forwarding issues. Many times, it is required to identify the label, which is assigned to a LSP, on a particular routing node.

  1. If the MPLS LSP name is known and you want to find the associated labels, use the following command on any routing node in the path:

    show rsvp session name <lsp name>
    For example:

    You want to identify the labels that are associated with the test.1234 LSP:
    > show rsvp session name test.1234

    Ingress RSVP: 1 sessions
    Total 0 displayed, Up 0, Down 0

    Egress RSVP: 0 sessions
    Total 0 displayed, Up 0, Down 0

    Transit RSVP: 60135 sessions
    To From State Rt Style Labelin Labelout LSPname
    4.4.4.4 6.6.6.6 Up 0 1 SE 796891 596963 test.1234
    Total 1 displayed, Up 1, Down 0

    The above example indicates that the test.1234 LSP has 796891 as the input label and 596963 as the output label.2)


  • If you are aware of the label and want to identify the LSP name, use the following command:

    Note : As label assignment is performed on a hop to hop basis, this command is specific to a routing node.
      show route table mpls.0 label
    For example:

    Assume that you are looking for a LSP that corresponds to the 796891 input label:
    > show route table mpls.0 label 796891

    mpls.0: 63768 destinations, 63768 routes (63768 active, 0 holddown, 0 hidden)
    + = Active Route, - = Last Active, * = Both

    796891 *[RSVP/7/1] 00:02:40, metric 1
    > to 68.1.5.134 via ae3.0, label-switched-path test.1234