Step 1: Verify the CSPF Failure

Purpose

To simulate a configuration error on the network, router R5 has the administrative group coloring removed from interface so-0/0/0. The result is a CSPF failure at R5 because there is no longer a path between R1 and R6 that includes the red color.

Action

To confirm that the LSP is down and verify the configuration on routers R1 and R5, enter the following JUNOS CLI operational mode commands:

user@host> clear mpls lsp

user@host> show mpls lsp extensive

Sample Output 1

user@R1> clear mpls lsp 

[edit protocols mpls]

user@R1# run show mpls lsp extensive

Ingress LSP: 1 sessions

10.0.0.6

  From: 0.0.0.0, State: Dn, ActiveRoute: 0, LSPname: R1-to-R6

  ActivePath: (none)

  LoadBalance: Random

  Metric: 100

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

  Primary                    State: Dn

          Include: red    Exclude: blue

    Will be enqueued for recomputation in 24 second(s).

    9 May 11 20:12:28 CSPF failed: no route toward 10.0.0.6

    8 May 11 20:12:28 Clear Call

    7 May 11 20:12:28 Deselected as active

    6 May 11 19:31:42 Selected as active path

    5 May 11 19:31:42 Record Route:  10.1.15.2 10.1.56.2

    4 May 11 19:31:42 Up

    3 May 11 19:31:42 Originate Call

    2 May 11 19:31:42 CSPF: computation result accepted

    1 May 11 19:31:12 CSPF failed: no route toward 10.0.0.6[5 times]

  Created: Wed May 11 19:29:17 2005

Total 1 displayed, Up 0, Down 1

[...Output truncated...]

Sample Output 2

[edit protocols mpls]

user@R5# run show mpls lsp 

Ingress LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

Egress LSP: 0 sessions

Total 0 displayed, Up 0, Down 0

Transit LSP: 1 sessions

To              From            State   Rt Style Labelin Labelout LSPname 

10.0.0.1        10.0.0.6        Up       1  1 FF  100352        3 R6-to-R1

Total 1 displayed, Up 1, Down 0

What It Means

Sample Output 1 from ingress router R1 shows that the clear mpls lsp command was issued to confirm that R1 cannot reestablish LSP R1-to-R6. The sample output from the show mpls lsp extensive command shows that LSP R1-to-R6 is down, State: Dn and ActivePath: (None); and that the CSPF has failed, CSPF failed: no route toward 10.0.0.6.

Sample Output 2 from transit router R5 shows that LSP R1-to-R6 is not included in the output, indicating that the LSP is not transiting R5.

Most network problems appear as a local CSPF failure, as shown in the sample output. The CSPF failure indicates that no path meeting the constraints for the LSP can be found in the router's traffic engineering database. To resolve these problems effectively, use CSPF tracing on the ingress router, and analyze the traffic engineering database to locate the node that should meet the constraints.