Low performance and dropped packets in Cat 6500

[daniel.espi]

Hello,

I'm experiencing problems in my Cat 6500. It only has one interface connected but its performance is very low. I've done many ping test and i always see dropped pings.

The show mls cef exception status shows:

APOLO#           sh mls cef exception status 
Current IPv4 FIB exception state = TRUE
Current IPv6 FIB exception state = FALSE
Current MPLS FIB exception state = FALSE

It seems FIB is in exception state, could it be the cause for performance problems?

What do i have to do to solve this problem?  Reloaded it?

Thanks

[Dale Miller]

Yes, the FIB exception can be the cause for your preformance problems. It can lead to high CPU and connectivity problems throughout your network.  The exception being true means the switch has exceed the amount of routes it can maintain in TCAM.

You can review the total amount of IPv4 routes allowed using command "show mls cef max" and compare that to how many routes currently in TCAM with command "show mls cef sum".  Please note, once you exceed the amount of routes allowed the FIB exception state will not be cleared until you reload the switch. This holds true if you exceed the limit and dropped back below (possibly due to a change in the network).

To avoid this issue you can use route summarization to minimize the amount of routes learned. To  maximum number of the routes that can be programmed in the hardware allowed per protocol, use the mls cef maximum-routes command .  

http://www.cisco.com/en/US/docs/ios/ipswitch/command/reference/isw_i1.html#wp1087660

If you have the TCAM resources available to increase the amount of IPv4 routes I recommend you plan to make the configuration change prior to the reload so you only have to reload once. 

Regards,

Dale