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Verify the CSPF Failure



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.


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

Sample Output 1

Sample Output 2


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

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.