Contradictory 'show' output re: CEF

[rpast]

Hello all -

On a 4506 L3 switch, a predecessor configured 'no ip route-cache cef' on the vlan SVIs. I would like to re-enable cef, but now am not sure if it is actually disabled on these interfaces. 'Sh int switching' seems to confirm the configuration by showing all packets process-switched for the vlans. On the other hand, 'sh ip cef' has entries for those vlans , and 'sh int vlan stats' shows most all packets being switched in hardware (not processed). So is cef enabled on these interfaces, or not?

Stated another way, how is the output from 'sh int switching' different than the output for 'sh int vlan stats'?

Thank you for any help you can provide

 

[burtsbees]

Does "ip cef" show up in "sh run"?

Burt

 

[rpast]

I'll check tomorrow. But isn't it on by default, and therefore only showing up in the config when it is off?

 

[burtsbees]

No---it shows up when it's on, and I don't remember offhand if it is turned on by default in all routers/IOS versions.

Burt

 

[rpast]

“Ip cef” does not show in the config -- IOS version 12.2(31). Yet CEF is running.

And it definitely appears to be running on the interfaces configured with ‘no ip route-cache cef’. “Show adj detail” has entries. At this point, I’m concluding that CEF is not allowed to be disabled on this switch. An article at

http://searchnetworkingchannel.techtarget.com/generic/0,295582,sid100_gci1261924,00.html

indicates this, although I would think that the attempt to disable it would have yielded an error message, rather than just allowing the “no ip route-cache cef” to be entered, and then just having cef continue to run.

Even so, I’m curious how the output from 'sh int switching' seems to contradict the output for 'sh int vlan stats'. As you can see from the following, all traffic is switched in hardware per the first output, and process-switched per the second output.

12fl4506#sh int vlan21 stats
Vlan21
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 0 0
Route cache 0 0 0 0
Hardware 1011470547 1236839140642 488636118 182140106530
Total 1011470547 1236839140642 488636118 182140106530

12fl4506#sh int vlan21 switching
Vlan21 ICN Broadcast Domain
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 0 Drops 0

Protocol Path Pkts In Chars In Pkts Out Chars Out
IP Process 344776 39992701 14731 1031170
Cache misses 0
Fast 0 0 0 0
Auton/SSE 0 0 0 0
ARP Process 105336 7258882 127120 7627200
Cache misses 0
Fast 0 0 0 0
Auton/SSE 0 0 0 0


Thanks for your input.