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Cisco IOS XR Troubleshooting Guide for the Cisco CRS-1 Router
OL-21483-02
Chapter 13 Troubleshooting Load Balancing
Configuration Examples for Troubleshooting Load Balancing
Checking the Route Metric
Although OSPF is configured to support three equal cost paths, only two active paths are displayed in
the routing table. Use the show ospf interface command to determine the reason:
RP/0/RP0/CPU0:RouterB# show ospf 200 interface brief
Fri Sep 19 11:39:35.212 PST DST
* indicates MADJ interface
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Gi0/6/5/5 200 0 10.12.48.2/24 1 BDR 1/1
Gi0/6/5/6 200 0 10.12.44.2/24 1 BDR 1/1
Gi0/6/5/7 200 0 10.12.40.2/24 10 BDR 1/1
Gi0/6/5/7 has a higher cost thanGi0/6/5/6 and Gi0/6/5/7, and is therefore excluded. Use the show run
command to confirm that Gi0/6/7 is configured with the cost 10 command:
RP/0/RP0/CPU0:RouterB# show run router ospf 200
Fri Sep 19 11:46:36.142 PST DST
router ospf 200
maximum paths 3
area 0
interface Loopback1
passive enable
!
...
interface GigabitEthernet0/6/5/7
cost 10
Use the no cost 10 interface subcommand in the router ospf area configuration mode to restore the
default cost to GigabitEthernet0/6/5/7. The show route command now displays three paths to the
194.168.20.0 network:
RP/0/RP0/CPU0:RouterB# show route 10.1.2.1
Fri Sep 19 11:52:46.942 PST DST
Routing entry for 10.1.2.1/32
Known via "ospf 200", distance 110, metric 2, type intra area
Installed Sep 19 11:52:34.487 for 00:00:12
Routing Descriptor Blocks
10.12.48.1, from 10.1.2.1, via GigabitEthernet0/6/5/5
Route metric is 2
10.12.44.1, from 10.1.2.1, via GigabitEthernet0/6/5/6
Route metric is 2
10.12.40.1, from 10.1.2.1, via GigabitEthernet0/6/5/7
Route metric is 2
No advertising protos.
The next step is to look at how Cisco Express Forwarding uses the information in the routing table to
forward packets.
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