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Checklist for Examining a CSPF Failure

Problem

The ingress router determines the physical path for each label-switched path (LSP) by applying a Constrained Shortest Path First (CSPF) algorithm to the information in the traffic engineering database (TED). This checklist provides the links and commands for a real-world scenario in which the CSPF algorithm fails because of the incorrect association of links with administrative groups (also known as link coloring). The links point to discussions of some basic approaches to monitoring and examining a CSPF failure, including how, when, and why you use specific commands. The links also point to an examination of an example CSPF log file, traffic engineering database, and corrective action for the example scenario. (See Table 13.)

Solution

Table 13: Checklist for Examining a CSPF Failure

Tasks

  
Case Study for a CSPF Failure  
  1. Verify That the LSP Is Established

show mpls lsp extensive
  1. Check the Administrative Group Configuration

show configuration protocols mpls
show mpls interface
show ted database extensive nodeID

Examining a CSPF Failure  
  1. Verify the CSPF Failure

clear mpls lsp
show mpls lsp extensive
  1. Examine the CSPF Log File

monitor start filename
 show log filename
 monitor stop

  1. Examine the Traffic Engineering Database

show ted database extensive

For output filtered for color:
show ted database extensive nodeID | match “(NodeID | To: | Color)"

  1. Check the Administrative Group Configuration on R5

edit
[edit protocols mpls]
show
delete interface so-0/0/1 admin-group
set interface so-0/0/0 admin-group red
show
commit

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