qos from lan to layer 3 switchports

Unanswered Question
May 26th, 2009
User Badges:

Hi all

when I have qos enabled in my layer 2 switches, these switches then plugs into my layer 3 switch which routes to my distribution network,

what qos config do I need to do on the L3 switchports, can i still do a mls qos trust dscp ?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
cisco_lad2004 Tue, 05/26/2009 - 09:21
User Badges:
  • Gold, 750 points or more


Depends on what is being marked by L2 switch.

If it is COS bits then you have to use mls qos trust cos which should then be copied to DSCP bit at L3 switch.

If you are marking or remarking DSCP, then trust DSCP will do.

Either way, with QOS always test !



cisco_lad2004 Wed, 05/27/2009 - 03:35
User Badges:
  • Gold, 750 points or more

SPAN port + sniffer then you are 100% sure.

Else you could have use a policy map on a third device and see if your counters are incrementing for packets matching your class map.


This Discussion