Step 1: Verify the LSP

Purpose

Typically, you use the show mpls lsp extensive command to verify the LSP. However for quick verification of the LSP state, use the show mpls lsp command. If the LSP is down, use the extensive option (show mpls lsp extensive) as a follow-up. If your network has numerous LSPs, you might consider specifying the name of the LSP, using the name option (show mpls lsp name name or show mpls lsp name name extensive).

Action

To determine whether the LSP is up, enter the following command from the ingress router:

user@host> show mpls lsp extensive

Sample Output 1

user@R1> show mpls lsp extensive

Ingress LSP: 1 sessions

10.0.0.6

  From: 10.0.0.1, State: Dn, ActiveRoute: 0, LSPname: R1-to-R6

  ActivePath: (none)

  LoadBalance: Random

  Encoding type: Packet, Switching type: Packet, GPID: IPv4

  Primary                    State: Dn

    2 Oct 27 15:06:05 10.1.13.2: No Route toward dest[4 times]

    1 Oct 27 15:05:56 Originate Call

  Created: Wed Oct 27 15:05:55 2004

Total 1 displayed, Up 0, Down 1

Egress LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

Transit LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

user@R3> show mpls lsp extensive 

Ingress LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

Egress LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

Transit LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

user@R6> show mpls lsp extensive

Ingress LSP: 1 sessions

10.0.0.1

  From: 10.0.0.6, State: Dn, ActiveRoute: 0, LSPname: R6-to-R1

  ActivePath: (none)

  LoadBalance: Random

  Encoding type: Packet, Switching type: Packet, GPID: IPv4

  Primary                    State: Dn

    Will be enqueued for recomputation in 22 second(s).

    1 Oct 27 14:59:12 CSPF failed: no route toward 10.0.0.1[4 times]

  Created: Wed Oct 27 14:57:44 2004

Total 1 displayed, Up 0, Down 1

Egress LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

Transit LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

What It Means

The sample output shows that the LSP is down in both directions, from R1 to R6, and from R6 to R1. The output from R1 shows that R1 is using a no-cspf LSP since it tried to originate the call without being able to reach the destination. The output from R6 shows that the Constrained Shortest Path First (CSPF) algorithm failed, resulting in no route to destination 10.0.0.1.