mls qos use policy-map for marking

Hi Group Study experts

Recently i tested use policy-map for marking on my 3550 switch. And found some problems.

First, i configured a class map to match all the traffic, and use policy-map to match that class to set dscp EF. Then i applied that policy map to the incoming direction of an access port(layer 2), which is connected to a router. After that i tried generate some traffic from the router, and then on the switch, i found there is nothing matched when i tried "show policy-map interface".

but after i changed the switch port to a layer 3 port, the marking is successfully done.

so i am wondering policy-map marking is only working on a layer 3 port. Please help me to confirm it. Thanks a lot.

And by the way, what is the meaning if i put "mls qos trust dscp " on a trunk port?? since trunk port is a layer 2 port, it wont check layer 3 portion, is it??

                                               
Received on Wed Apr 21 2010 - 05:50:21 ART