Step 2: Examine the CSPF Log File
Purpose
After you have confirmed that the LSP is down, obtain more information about the possible cause of the failure.
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NOTE: To obtain useful information from the CSPF log file, make sure that CSPF tracing is configured on the ingress router. For more information on configuring CSPF tracing, see Configuring CSPF Tracing. |
Action
To examine the CSPF log file, enter the following JUNOS CLI operational mode commands:
user@host>monitor startfilename
user@host>show logfilename
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NOTE: To stop monitoring CSPF, issue the |
Sample Output
user@R1> monitor start cspf
[edit protocols mpls]
user@R1# run show log cspf-failed3
May 27 10:22:23 trace_on: Tracing to "/var/log/cspf" started
May 27 10:22:29 CSPF adding path R1-to-R6(primary ) to CSPF queue 1
May 27 10:22:29 CSPF creating CSPF job
May 27 10:22:29
May 27 10:22:29 CSPF for path R1-to-R6(primary ), begin at R1.00 , starting
May 27 10:22:29path include: 0x00000100<< administration group red
May 27 10:22:29path exclude: 0x00000010<< administration group blue
May 27 10:22:29 bandwidth: CT0=0bps ; setup priority: 0; random
May 27 10:22:29 CSPF final destination 10.0.0.6
May 27 10:22:29 CSPF starting from R1.00 (10.0.0.1) to 10.0.0.6, hoplimit 254
May 27 10:22:29 constraint include 0x00000100
May 27 10:22:29 constraint exclude 0x00000010
May 27 10:22:29 Node R1.00 (10.0.0.1) metric 0, hops 0, avail 32000 32000 32000 32000
May 27 10:22:29 Link 10.1.12.1->10.1.12.2(R2.00/10.0.0.2) metric 10 color 0x00000000 bw 155.52Mbps
May 27 10:22:29 Reverse Link for 10.1.12.1->10.1.12.2 is 10.1.12.2->10.1.12.1
May 27 10:22:29 link fails include 0x00000100
May 27 10:22:29 Link 10.1.15.1->10.1.15.2(R5.00/10.0.0.5) metric 10 color 0x00000100 bw 155.52Mbps
May 27 10:22:29 Reverse Link for 10.1.15.1->10.1.15.2 is 10.1.15.2->10.1.15.1
May 27 10:22:29 link's interface switch capability descriptor #1
May 27 10:22:29 encoding: Packet, switching: Packet
May 27 10:22:29 link passes constraints
May 27 10:22:29 Link 10.1.13.1->10.1.13.2(R3.00/10.0.0.3) metric 10 color 0x00000010 bw 155.52Mbps
May 27 10:22:29 Reverse Link for 10.1.13.1->10.1.13.2 is 10.1.13.2->10.1.13.1
May 27 10:22:29 link fails include 0x00000100
May 27 10:22:29 Node R5.00 (10.0.0.5) metric 10, hops 1, avail 32000 32000 32000 32000
May 27 10:22:29 Link 10.1.15.2->10.1.15.1(R1.00/10.0.0.1) metric 10 color 0x00000100 bw 155.52Mbps
May 27 10:22:29 skipped: end point already visited
May 27 10:22:29 Link 10.1.45.2->10.1.45.1(R4.00/10.0.0.4) metric 10 color 0x00000000 bw 155.52Mbps
May 27 10:22:29 Reverse Link for 10.1.45.2->10.1.45.1 is 10.1.45.1->10.1.45.2
May 27 10:22:29 link fails include 0x00000100
May 27 10:22:29 Link 10.1.56.1->10.1.56.2(R6.00/10.0.0.6) metric 10 color 0x00000000 bw 155.52Mbps
May 27 10:22:29Reverse Link for 10.1.56.1->10.1.56.2 is 10.1.56.2->10.1.56.1
May 27 10:22:29link fails include 0x00000100
May 27 10:22:29 CSPF completed in 0s
May 27 10:22:29 CSPF couldn't find a route to 10.0.0.6
May 27 10:22:29 CSPF for R1-to-R6 done!
monitor stop
What It Means
The sample output shows that the monitor start cspf command was issued to start displaying entries in the cspf log file in real time. The cspf log file is generated by the routing protocol process after the file is configured with the traceoptions statement at the [edit protocols mpls] hierarchy level. In this example, the cspf log file is configured with the cspf, cspf-node, and cspf-link flags to provide the most granular information about the steps taken by the CSPF algorithm. For information on configuring CSPF tracing, see Configuring CSPF Tracing.
The only link that passes the color constraint is between R1 and R5, 10.1.15.0/32. The CSPF algorithm is a locally run algorithm, which makes its calculations on a given router. When the CSPF algorithm runs on R5, it prunes 10.1.15.2 and selects 10.1.56.1 to send the message to R6.The link between R5 and R6 10.1.56.0/32 does not pass the color constraints, indicating a problem with R5. At this stage, it is useful to examine the traffic engineering database to determine which link on R5 should be associated with the red color.