Giuseppe Larosa Mon, 05/31/2010 - 02:10
User Badges:
  • Super Silver, 17500 points or more
  • Hall of Fame,

    Founding Member

Hello Manie,

this is a general requirement for QoS on multilayer switches.

Each frame or packet is associated with an internal QoS tag that by implementation choice is a DSCP field

As a result of this CEF is needed

To be noted in multilayer switches disabling CEF is  impossible they need it.

On SW based  routers almost all modern QoS tools require CEF to be enabled and even less recent tools like CAR, so it is not a surprise that CEF has to be enabled to support autoQoS

Hope to help


Calin Chiorean Mon, 05/31/2010 - 02:22
User Badges:
  • Silver, 250 points or more

In addition to what Giuseppe said (which is actually a very good explanation) I want to add that AutoQoS is using NBAR to identify various applications and traffic types and CEF is requirement of NBAR.

If you look here:

you'll see at Restriction, that NBAR does not support multicast and other non-CEF switching mode.


This Discussion