The ingress router determines the physical path for each LSP by applying a CSPF algorithm to the information in the traffic engineering database (TED). CSPF is a shortest-path-first (SPF) algorithm that has been modified to take into account specific restrictions when calculating the shortest path across a network. Links that do not comply with the restrictions are removed from the tree and cannot be factored into the resulting SPF calculations. When compliant routes cannot be found, the output of the CSPF algorithm is a CSPF event or error message that can appear in the output of the show mpls lsp extensive command.
To display CSPF messages, enter the following JUNOS command-line interface (CLI) operational mode command from the ingress router:
user@R1# run 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 Will be enqueued for recomputation in 3 second(s). 68 Jan 5 10:02:56 CSPF failed: no route toward 10.0.0.6[9 times] 67 Jan 5 09:58:33 Deselected as active 66 Jan 5 09:58:33 CSPF failed: no route toward 10.0.0.6 65 Jan 5 09:58:33 Clear Call 64 Jan 5 09:58:33 Session preempted 63 Jan 5 09:58:33 Down 62 Jan 5 09:58:32 CSPF failed: no route toward 10.0.0.6[2 times] 61 Jan 5 09:57:55 10.1.36.2: Explicit Route: wrong delivery 60 Jan 5 09:57:34 CSPF failed: no route toward 10.0.0.6[2 times] 59 Jan 5 09:57:28 CSPF: link down/deleted 10.1.36.1(R3.00/10.0.0.3)->10.1.36.2(R6.00/10.0.0.6) 58 Jan 5 09:54:37 Selected as active path 57 Jan 5 09:54:37 Record Route: 10.1.13.2 10.1.36.2 56 Jan 5 09:54:37 Up 55 Jan 5 09:54:37 Originate Call 54 Jan 5 09:54:37 CSPF: computation result accepted [...Output truncated...]
The sample output from ingress router R1 shows extensive ingress LSP information, including LSP events that led to an LSP failure, with the most recent events at the top. The last line before the history log begins indicates the length of time the router waits before attempting to re-signal the LSP, three seconds in this instance.
LSP events in bold are described in this topic. Descriptions include sample output of the LSP event, an explanation of what the event means, the possible cause of the event, and any possible actions that you can take.
For completeness, events not included in this example output are also described in this topic to show LSP events that did not occur in the example network configuration, but might occur in your network. The output for these events includes the prompt user@host rather than the usual user@R1 prompt.
