MLS and CEF

vdadlaney · ‎12-03-2008

Hi, referring to this document "http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00804c5472.shtml"

and the section "Difference between IP CEF and MLS CEF" it says to use show ip cef exact-route <src-ip> <dst-ip> to view the next hop however before that it says that when using MLS CEF the packets are hardware switched hence wouldn't that mean that "show mls cef exact-route" be more accurate. Am I reading this incorrectly?

Per my understanding any show mls cef commands provide information on the PFC wheras any commands with show ip cef provide information on the RP. Is that correct? thx

Laurent Aubert · ‎12-03-2008

Hi,

Correct.

sh ip cef will show you the FIB created by the RP

sh mls cef will show you how the PFC/DFC programmed this FIB entry in the FIB TCAM used for Hw lookup.

Hope this helps

Laurent.

vdadlaney · ‎12-03-2008

Hi Laurent,

Thank you for the response. Could you please confirm if this means that the doc specified in my original post is incorrect. Thx

Laurent Aubert · ‎12-04-2008

Hi,

I understand it's confusing ;-)

Actually both commands are the same. The main difference is the sh mls cef exact-route will give you the information from the adjacency table as well (destination MAC + output VLAN).

So if you're interesting only by the next-hop address, the document is correct.

Thanks

Laurent.