Step 3: Trace Links Visited During CSPF Computations
Purpose
The configuration of the cspf-link flag provides details in the log file about the links visited during CSPF computations. The link information is in addition to the overview information provided by the cspf flag, and the node information provided by the cpsf-node flag.
Action
To run trace links visited during CSPF computations and examine the CSPF log file, enter the following JUNOS CLI commands:
[edit protocols mpls]
user@R1#run monitor startfilename
user@R1#run show logfilename
user@R1# run show ted database
 |
NOTE: To stop monitoring CSPF, issue the |
Sample Output 1
[edit protocols mpls]
user@R1# show
traceoptions {
file cspf-link;
flag cspf;
flag cspf-link;
}
label-switched-path R6-to-R1 {
to 10.0.0.1;
}
interface so-0/0/0.0;
interface so-0/0/1.0;
interface so-0/0/2.0;
interface so-0/0/3.0;
Sample Output 2
[edit protocols mpls]
user@R1# run show log cspf-link | no-more
Apr 29 13:29:52 trace_on: Tracing to "/var/log/cspf-link" started
Apr 29 13:30:27 RPD_MPLS_LSP_DOWN: MPLS LSP R1-to-R6 down on primary()
Apr 29 13:30:27 RPD_MPLS_PATH_DOWN: MPLS path down on LSP R1-to-R6
Apr 29 13:30:27 CSPF adding path R1-to-R6(primary) to CSPF queue 1
Apr 29 13:30:27 CSPF creating CSPF job
Apr 29 13:30:27
Apr 29 13:30:27 CSPF for path R1-to-R6(primary), begin at R1.00, starting
Apr 29 13:30:27 bandwidth: CT0=0bps; setup priority: 0; random
Apr 29 13:30:27 CSPF final destination 10.0.0.6
Apr 29 13:30:27 CSPF starting from R1.00 (10.0.0.1) to 10.0.0.6, hoplimit 254
Apr 29 13:30:27 Node R1.00 (10.0.0.1) metric 0, hops 0, avail 32000 32000 32000 32000
Apr 29 13:30:27 Link 10.1.13.1->10.1.13.2(R3.00/10.0.0.3) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.13.1->10.1.13.2 is 10.1.13.2->10.1.13.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 Link 10.1.12.1->10.1.12.2(R2.00/10.0.0.2) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.12.1->10.1.12.2 is 10.1.12.2->10.1.12.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 Link 10.1.15.1->10.1.15.2(R5.00/10.0.0.5) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.15.1->10.1.15.2 is 10.1.15.2->10.1.15.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 Node R3.00 (10.0.0.3) metric 10, hops 1, avail 32000 32000 32000 32000
Apr 29 13:30:27 Link 10.1.13.2->10.1.13.1(R1.00/10.0.0.1) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 skipped: end point already visited
Apr 29 13:30:27 Link 10.1.34.1->10.1.34.2(R4.00/10.0.0.4) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.34.1->10.1.34.2 is 10.1.34.2->10.1.34.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 Link 10.1.23.2->10.1.23.1(R2.00/10.0.0.2) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.23.2->10.1.23.1 is 10.1.23.1->10.1.23.2
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 metric: 20 vs 10; hops: 2 vs 1; avail: 32000 32000 32000 32000
Apr 29 13:30:27 Link 10.1.36.1->10.1.36.2(R6.00/10.0.0.6) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.36.1->10.1.36.2 is 10.1.36.2->10.1.36.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 Node R5.00 (10.0.0.5) metric 10, hops 1, avail 32000 32000 32000 32000
Apr 29 13:30:27 Link 10.1.15.2->10.1.15.1(R1.00/10.0.0.1) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 skipped: end point already visited
Apr 29 13:30:27 Link 10.1.45.2->10.1.45.1(R4.00/10.0.0.4) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.45.2->10.1.45.1 is 10.1.45.1->10.1.45.2
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 metric: 20 vs 20; hops: 2 vs 2; avail: 32000 32000 32000 32000
Apr 29 13:30:27 Better path: random wins
Apr 29 13:30:27 Link 10.1.56.1->10.1.56.2(R6.00/10.0.0.6) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.56.1->10.1.56.2 is 10.1.56.2->10.1.56.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 metric: 20 vs 20; hops: 2 vs 2; avail: 32000 32000 32000 32000
Apr 29 13:30:27 Old path is better
Apr 29 13:30:27 Node R2.00 (10.0.0.2) metric 10, hops 1, avail 32000 32000 32000 32000
Apr 29 13:30:27 Link 10.1.12.2->10.1.12.1(R1.00/10.0.0.1) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 skipped: end point already visited
Apr 29 13:30:27 Link 10.1.23.1->10.1.23.2(R3.00/10.0.0.3) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 skipped: end point already visited
Apr 29 13:30:27 Link 10.1.24.1->10.1.24.2(R4.00/10.0.0.4) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.24.1->10.1.24.2 is 10.1.24.2->10.1.24.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 metric: 20 vs 20; hops: 2 vs 2; avail: 32000 32000 32000 32000
Apr 29 13:30:27 Old path is better
Apr 29 13:30:27 Link 10.1.26.1->10.1.26.2(R6.00/10.0.0.6) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.26.1->10.1.26.2 is 10.1.26.2->10.1.26.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 metric: 20 vs 20; hops: 2 vs 2; avail: 32000 32000 32000 32000
Apr 29 13:30:27 Old path is better
Apr 29 13:30:27 Node R4.00 (10.0.0.4) metric 20, hops 2, avail 32000 32000 32000 32000
Apr 29 13:30:27 Link 10.1.34.2->10.1.34.1(R3.00/10.0.0.3) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 skipped: end point already visited
Apr 29 13:30:27 Link 10.1.24.2->10.1.24.1(R2.00/10.0.0.2) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 skipped: end point already visited
Apr 29 13:30:27 Link 10.1.45.1->10.1.45.2(R5.00/10.0.0.5) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 skipped: end point already visited
Apr 29 13:30:27 Link 10.1.46.1->10.1.46.2(R6.00/10.0.0.6) metric 10 color 0x00000000 bw 155.52Mbps
Apr 29 13:30:27 Reverse Link for 10.1.46.1->10.1.46.2 is 10.1.46.2->10.1.46.1
Apr 29 13:30:27 link's interface switch capability descriptor #1
Apr 29 13:30:27 encoding: Packet, switching: Packet
Apr 29 13:30:27 link passes constraints
Apr 29 13:30:27 metric: 30 vs 20; hops: 3 vs 2; avail: 32000 32000 32000 32000
Apr 29 13:30:27 Node R6.00 (10.0.0.6) metric 20, hops 2, avail 32000 32000 32000 32000
Apr 29 13:30:27 CSPF Reached target
Apr 29 13:30:27 CSPF completed in 0.001880s
Apr 29 13:30:27 CSPF ERO for R1-to-R6(primary) (2 hops)
Apr 29 13:30:27 node 10.1.13.2/32
Apr 29 13:30:27 node 10.1.36.2/32
Apr 29 13:30:27 CSPF for R1-to-R6 done!
Apr 29 13:30:27 RPD_MPLS_PATH_UP: MPLS path up on LSP R1-to-R6
Apr 29 13:30:27 RPD_MPLS_LSP_UP: MPLS LSP R1-to-R6 up on primary() Route 10.1.13.2 10.1.36.2
Sample Output 3
user@R1# run show ted database | no-more
TED database: 6 ISIS nodes 6 INET nodes
ID Type Age(s) LnkIn LnkOut Protocol
R1.00(10.0.0.1)Rtr 148 3 3IS-IS(2)
To: R3.00(10.0.0.3), Local: 10.1.13.1, Remote: 10.1.13.2
To: R5.00(10.0.0.5), Local: 10.1.15.1, Remote: 10.1.15.2
To: R2.00(10.0.0.2), Local: 10.1.12.1, Remote: 10.1.12.2
ID Type Age(s) LnkIn LnkOut Protocol
OSPF(0.0.0.0)
To: R3.00(10.0.0.3), Local: 10.1.13.1, Remote: 10.1.13.2
To: R5.00(10.0.0.5), Local: 10.1.15.1, Remote: 10.1.15.2
To: R2.00(10.0.0.2), Local: 10.1.12.1, Remote: 10.1.12.2
ID Type Age(s) LnkIn LnkOut Protocol
R2.00(10.0.0.2) Rtr 580 4 4 IS-IS(2)
To: R1.00(10.0.0.1), Local: 10.1.12.2, Remote: 10.1.12.1
To: R3.00(10.0.0.3), Local: 10.1.23.1, Remote: 10.1.23.2
To: R4.00(10.0.0.4), Local: 10.1.24.1, Remote: 10.1.24.2
To: R6.00(10.0.0.6), Local: 10.1.26.1, Remote: 10.1.26.2
ID Type Age(s) LnkIn LnkOut Protocol
OSPF(0.0.0.0)
To: R1.00(10.0.0.1), Local: 10.1.12.2, Remote: 10.1.12.1
To: R3.00(10.0.0.3), Local: 10.1.23.1, Remote: 10.1.23.2
To: R4.00(10.0.0.4), Local: 10.1.24.1, Remote: 10.1.24.2
To: R6.00(10.0.0.6), Local: 10.1.26.1, Remote: 10.1.26.2
ID Type Age(s) LnkIn LnkOut Protocol
R3.00(10.0.0.3) Rtr 390 4 4 IS-IS(2)
To: R1.00(10.0.0.1), Local: 10.1.13.2, Remote: 10.1.13.1
To: R4.00(10.0.0.4), Local: 10.1.34.1, Remote: 10.1.34.2
To: R2.00(10.0.0.2), Local: 10.1.23.2, Remote: 10.1.23.1
To: R6.00(10.0.0.6), Local: 10.1.36.1, Remote: 10.1.36.2
ID Type Age(s) LnkIn LnkOut Protocol
OSPF(0.0.0.0)
To: R1.00(10.0.0.1), Local: 10.1.13.2, Remote: 10.1.13.1
To: R4.00(10.0.0.4), Local: 10.1.34.1, Remote: 10.1.34.2
To: R2.00(10.0.0.2), Local: 10.1.23.2, Remote: 10.1.23.1
To: R6.00(10.0.0.6), Local: 10.1.36.1, Remote: 10.1.36.2
ID Type Age(s) LnkIn LnkOut Protocol
R4.00(10.0.0.4) Rtr 677 4 4 IS-IS(2)
To: R3.00(10.0.0.3), Local: 10.1.34.2, Remote: 10.1.34.1
To: R5.00(10.0.0.5), Local: 10.1.45.1, Remote: 10.1.45.2
To: R2.00(10.0.0.2), Local: 10.1.24.2, Remote: 10.1.24.1
To: R6.00(10.0.0.6), Local: 10.1.46.1, Remote: 10.1.46.2
ID Type Age(s) LnkIn LnkOut Protocol
OSPF(0.0.0.0)
To: R3.00(10.0.0.3), Local: 10.1.34.2, Remote: 10.1.34.1
To: R5.00(10.0.0.5), Local: 10.1.45.1, Remote: 10.1.45.2
To: R2.00(10.0.0.2), Local: 10.1.24.2, Remote: 10.1.24.1
To: R6.00(10.0.0.6), Local: 10.1.46.1, Remote: 10.1.46.2
ID Type Age(s) LnkIn LnkOut Protocol
R5.00(10.0.0.5) Rtr 609 3 3 IS-IS(2)
To: R1.00(10.0.0.1), Local: 10.1.15.2, Remote: 10.1.15.1
To: R4.00(10.0.0.4), Local: 10.1.45.2, Remote: 10.1.45.1
To: R6.00(10.0.0.6), Local: 10.1.56.1, Remote: 10.1.56.2
ID Type Age(s) LnkIn LnkOut Protocol
OSPF(0.0.0.0)
To: R1.00(10.0.0.1), Local: 10.1.15.2, Remote: 10.1.15.1
To: R4.00(10.0.0.4), Local: 10.1.45.2, Remote: 10.1.45.1
To: R6.00(10.0.0.6), Local: 10.1.56.1, Remote: 10.1.56.2
ID Type Age(s) LnkIn LnkOut Protocol
R6.00(10.0.0.6) Rtr 633 4 4 IS-IS(2)
To: R3.00(10.0.0.3), Local: 10.1.36.2, Remote: 10.1.36.1
To: R4.00(10.0.0.4), Local: 10.1.46.2, Remote: 10.1.46.1
To: R5.00(10.0.0.5), Local: 10.1.56.2, Remote: 10.1.56.1
To: R2.00(10.0.0.2), Local: 10.1.26.2, Remote: 10.1.26.1
ID Type Age(s) LnkIn LnkOut Protocol
OSPF(0.0.0.0)
To: R3.00(10.0.0.3), Local: 10.1.36.2, Remote: 10.1.36.1
To: R4.00(10.0.0.4), Local: 10.1.46.2, Remote: 10.1.46.1
To: R5.00(10.0.0.5), Local: 10.1.56.2, Remote: 10.1.56.1
To: R2.00(10.0.0.2), Local: 10.1.26.2, Remote: 10.1.26.1
What It Means
Sample Output 1 shows the configuration of the cspf-link file, cspf flag, and cspf-link flag at the [edit protocols mpls traceoptions] hierarchy level. See Configuring CSPF Tracing for steps to configure CSPF tracing.
Sample Output 2 shows the contents of the cspf-link file in the /var/log/ directory on ingress router R1. The cspf-link file contains the CSPF computations logged when the cspf and cspf-link flags are configured at the [edit protocols mpls traceoptions] hierarchy level and after the run monitor start cspf and run show log cspf commands are issued.
Each line of output describes the steps taken by the CSPF algorithm to calculate the shortest path between the ingress and egress routers. Because the cspf-link flag is configured, the output shows the node and link information included in the calculations performed by the CSPF algorithm. For example, R1 (ingress router) has three links with three possible paths to the egress router (R6), Link 10.1.13.1->10.1.13.2, Link 10.1.12.1->10.1.12.2, and Link 10.1.15.1->10.1.15.2. In this instance, the CSPF algorithm selects the 10.1.13.1->10.1.13.2 link as the shortest path to the egress router.
The result of the CSPF algorithm is formed into a strict-hop ERO. For example, the ERO for the LSP R1-to-R6 contains two hops that pass through nodes 10.1.13.2/32 and 10.1.36.2.32. When the ERO is completed, CSPF for R1-to-R6 done!, the ERO is passed to the RSVP protocol process, where it is used for signaling and establishing the LSP in the network. The output shows RPD_MPLS_LSP_UP, indicating that the LSP was established successfully
Sample Output 3 shows a brief summary of the contents of the traffic engineering database. (For more detailed information, use the detail or extensive options.) When CSPF tracing is configured, the contents of the specified CSPF log file should correlate to the contents of the traffic engineering database; that is, the links shown in the output for the show log filename command should also appear in the output for the show ted database command. In the example network shown in Figure , the six nodes and all links associated with those nodes appear in the output of both commands.
The traffic engineering database is built through link-state routing protocol extensions that allow for the flooding of information regarding available link bandwidth, link coloring, and so on. Also, the traffic engineering database includes information contained in the OSPF and IS-IS databases. For example, R1 has three links configured at IS-IS Level 2, and the same three links configured in OPSF area 0.0.0.0.
For a more detailed examination of the traffic engineering database, see Examining a CSPF Failure.