CEF, NFFA, MLS

[m.baker]

HI,

I am a little confused as to which role each of the following plays or where it is used in forwarding decisions on different platforms ;

- CEF

- Netflow feature accelerate

- MLS

My understanding (that's what I want to confirm) is that some features use netflow for forwarding, some use cef/fib and depending on which platform like the 6500 may use hardware acceleration for ACLs.

So, it looks like depending on which platform and which feature you use, different forwarding technologies might be used.

Is there a good document that would describe roles/relationship between cef/Netflow feature acceleration and mls ?

Also, is cef used at all for any layer 4 forwarding decisions or does this involve netflow feature acceleration ?

Thanks !

[ruwhite]

CEF is a platform indenpendant software based switching mechanism. Netflow acceleration is a set of layer 4 tables that live on the CEF data structures to account for traffic, but which also accelerate certain layer 3 and 4 lookups for access control and other things of that nature. MLS is a hardware based switching mechanism that incorporates many of the features of CEF, and uses the CEF tables to build the hardware forwarding tables.

Probably the most confusing thing about this is that some platforms, like the 12000, use the term CEF to discuss their hardware forwarding engines. This is because the 12000 does use the same data structures as CEF for their hardware forwarding engines.

So, turn on the fastest method available to switch packets on the box you have--MLS, CEF, and if you're using a lot of layer 4 features, Netflow might speed your switching up as well.

:-)

Russ.W