A little confused.. When trouble shooting excessive output drops on a 3750 i noticed that al switching is done by cpu instead of "route cache". This 3750 has no ip routing enabled and no ip cef (ip cef is only for layer 3 i believe)..
But why isnt this switch using fast switching? I always thought that the first packet was processed by cpu but then it should do switching out of the learned/cached table e.g. fast switching.. But when i issue the command sh interface x/x stats the output is telling me that all packets are forwarded by CPU and none by "route cache"
?
Best Answer
If "IP routing" is disabled then your frames are NOT getting forwarded by your CPU. I am familiar with the output that you are talking about though.
The "show interfaces _ X/X stats" is a hidden command in IOS and as such it really isn't maintained the way most other show commands are.
If you do a "show proc cpu sorted | in Input" then you will see the "IP Input" process. That is the best way that you can see how much of a tax the forwarding plane is putting on your CPU.