CSPF: Computation Result Ignored Event

LSP Event

CSPF: computation result ignored

Sample Output

user@host> show mpls lsp extensive

[...Output truncated...]

34 May  8 13:27:39 CSPF failed: no route toward 10.11.2.10

   33 May  8 13:27:39 CSPF: link down/deleted 

0.0.0.0(eagle.04/0.0.0.0)->0.0.0.0(papst.00/10.255.11.215)

   32 May  8 13:27:12 CSPF: computation result ignored[16 times]

   31 May  8 13:19:35 Record Route:  10.11.1.9(flag=9 Label=100064) 

10.11.1.2(flag=9 Label=100048) 10.11.2.1(flag=1 Label=100048) 

[...Output truncated...]

What It Means

This LSP event indicates that during reoptimization, a CSPF path computation for a potential optimal path is performed. Various checks are carried out to evaluate whether the new path is better than the existing one. If the new path is not considered to be better, the CSPF computation results for the new path are ignored and the new path is not signaled.

Cause

There can be various reasons for ignoring computation of a potential optimal path:

• The optimization is purely metric based, so switching to the new path could increase bandwidth congestion on links.
• Switching to the new path could cause preemption.
• The metric of the new path is higher than that of the existing path.
• The metric is the same on the new and existing paths, but the number of hops in the new path is higher than on the existing path.