View/modify DSCP-to-txqueue maps on 4500X running IOS-XE?

[jan.vanderbiest]

Hi,

I am running IOS-XE 03.04.03.SG (15.1(2)SG3) on a Catalyst 4500X-32 and try to configure some QoS for voice and data. I cannot find a way to view or modify the DSCP to egress queue maps though.

I went through the config guide and looked everywhere but no success. Am I missing something?

Thanks in advance,

Jan

[Rajeev Sharma]

Hey Jan,

In sup6 and above the maps are supported in MQC way. Please have a look on the link given below:

http://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Video/qoscampuscat4500aag.pdf

HTH.

Regards,

RS.
 

[jan.vanderbiest]

Hi RS,

Thank you for your answer, and sorry for not getting back to you sooner.

I'm afraid this document tells me nothing new. It indeed states how to configure the queueing etc, but I still miss a way to view the DSCP (or cos) to queue mappings.

Jan

[jan.vanderbiest]

Hi,

After searching the half of the web I found that on Catalyst 4500 the (reverse) order of configuring classes within the policy-map determines the queue for each class. Besides the priority class (always first queue 0) and the default class (always last queue 7), the first configured class will take the second to last queue (queue 6), the second class will take the third to last queue (queue 5), and so on.

For example:

Policy Map AutoQos-VoIP-Output-Policy
 Class AutoQos-VoIP-Bearer-QosGroup
   set dscp ef
   set cos 5
   priority
  police cir percent 33
    conform-action transmit 
    exceed-action drop 
 Class AutoQos-VoIP-Control-QosGroup26
   set dscp af31
   set cos 3
   bandwidth remaining percent 5
 Class AutoQos-VoIP-Control-QosGroup24
   set dscp cs3
   set cos 3
   bandwidth remaining percent 5
 Class class-default
   dbl

Will result in:

Queue 0: Class AutoQos-VoIP-Bearer-QosGroup (priority)

Queue 7: Class class-default

Queue 6: Class AutoQos-VoIP-Control-QosGroup26

Queue 5: Class AutoQos-VoIP-Control-QosGroup24

I tested this on a Catalyst 4500 and can confirm this.

No idea why this is not well documented, or was I just looking in the wrong place?

- For the record: the place where I found this answer is p70 at http://d2zmdbbm9feqrf.cloudfront.net/2012/usa/pdf/BRKCRS-3142.pdf

Regards,

Jan