Multilayer switching - Basic question

[Hari Vishnu]

Hi,                  

Can any one please help me to clear my confustion on MLS. As far us I can understand MLS can forward based on L3/4 information. Two types are are Route cache and CEF based.

Nowdays , MLS uses CEF based architecture- Using FIB and Adjecency table. If my understanding is correct both are data structures and not hardware based. So how we can say that routing and switching is done on hardware also what specific hardware is required for multi layer switching support ?

Also, I have came across CEF in routers also, whats the difference when it comes to CEF in routers ?

Apologies for the basic question. But I would like to clear it as early as possible.

(Have gone through CISCO links and all but it couldn’t clear my above questions.)

[Richard Burts]

CEF is an approach or an architecture for forwarding IP traffic which uses the FIB and adjacency tables. In most IOS routers these functions are implemented in software. In most multilayer switches these functions are implemented in hardware, which are ASICs.

HTH

Rick

[Hari Vishnu]

HI Richard,

Thanks for the update. So do you mean the FIB and adj table will be ASIC in SWITCHES ? What about TCAM is that part of CEF (I dont think so).

Thanks,

H

[Richard Burts]

H

Here is a discussion from the support forum which you might find helpful

https://supportforums.cisco.com/thread/2146062

and here is another

https://supportforums.cisco.com/thread/2135687

HTH

Rick