Strange CEF Behavior?

mcallahan313 · ‎05-20-2008

Is there any valid reason that "sh ip cef x.x.x.x" would yield results different from the output of "sh ip cef"?

I have a situation where this is the case, and while the system should be using the path shown with "sh ip cef" it is actually trying to use the incorrect path displayed with "sh ip cef x.x.x.x"

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(Actual output, scrubbed for privacy)

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ROUTER#sh ip cef x.x.42.66

x.x.32.0/20, version 259912, epoch 0, cached adjacency y.y.192.129

0 packets, 0 bytes

via y.y.192.161, 0 dependencies, recursive

next hop y.y.192.129, GigabitEthernet2/0 via y.y.192.161/32

valid cached adjacency

ROUTER#sh ip cef | beg x.x.3

x.x.30.0/24 z.z.112.9 GigabitEthernet0/2

x.x.32.0/20 z.z.112.9 GigabitEthernet0/2 <<<Match>>>

x.x.32.0/21 z.z.112.9 GigabitEthernet0/2

x.x.32.0/24 z.z.112.9 GigabitEthernet0/2

x.x.33.0/24 z.z.112.9 GigabitEthernet0/2

x.x.34.0/24 y.y.192.129 GigabitEthernet2/0

x.x.35.0/24 y.y.192.129 GigabitEthernet2/0

x.x.36.0/24 y.y.192.129 GigabitEthernet2/0

x.x.37.0/24 z.z.112.9 GigabitEthernet0/2

x.x.38.0/24 z.z.112.9 GigabitEthernet0/2

x.x.39.0/24 z.z.112.9 GigabitEthernet0/2

x.x.44.0/24 z.z.112.9 GigabitEthernet0/2

smahbub · ‎05-26-2008

Cisco Express Forwarding (CEF) is advanced, Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the Internet, on networks characterized by intensive Web-based applications, or interactive sessions.

Refer the following url for more info on CEF configuration and troubleshooting:

http://www.cisco.com/en/US/docs/ios/12_2/switch/configuration/guide/xcfcefc.html#wp1000875

mcallahan313 · ‎05-27-2008

Thanks but the problem appears to have been a glitch in the IOS version that was in use, as a downgrade resolved my issue.