[c-nsp] RIP breaks with CEF enabled

[Adam Maloney]

Ran into a strange problem the other day on a 7206VXR running 12.2.  When 
CEF is enabled, I stopped getting RIP updates.  As soon as I disabled CEF, 
RIP started seeing the updates.

With CEF enabled, I turned on IP packet debugging (test environment with 
no traffic), the only thing I saw was "CEF: Try to CEF switch x.x.x.255 
from FastEthernet0/0"  Debugging ip rip events didn't show anything coming 
in, just the RIP sends from that router.

I googled that and checked bugtool but didn't find anything useful.