How can I verify QoS DSCP marking on a Cisco Catalyst 4500E?

  • Good afternoon,

    I've got a shiny new 4500E running 15.0(1r)SG7 that is set to replace an ailing 3750E. It is running ipbase for now.

    On the 3750 I was able to check out the incoming DSCP/CoS values on interfaces using the sh mls qos int gigX/X/X statistics. I can't seem to find any releveant commands to show the same info on this platform. Looking at the config documents here: Configuring Quality of Service there seems to be much less visibility into the individual interface markings.

    I would think it should have been displayed with a sh qos int tenX/X/X but all that gives me is this:

    SR-CORE-C4500X-32#sh qos int ten1/1/31
    Operational Port Trust State: Trusted
    Trust device: none
    Default DSCP: 0 Default CoS: 0
    Appliance trust: none

    Any ideas?

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  • Try this:

    show platform hardware interface ten1/1/31 statistics

    That should show you input bytes by CoS.

    The 4500 is a very different beast than the 3560/3750 for qos config and monitoring. Some other useful verification commands are:

    show platform hardware qos interface foo X/Y

    shows queue lengths and flow counts

    show interface foo X/Y counter detail

    shows interface egress packets by queue, queue drops and DBL drops.

    show policy-map interface foo X/Y

    Mostly useful if you are doing custom policy maps

    show interface foo X/Y capabilities

    If you want to know what the number and type of queues are available on a particular interface

    show qos maps

    To show the DSCP-CoS mappings

  • Sup6E/Sup7E based Catalysts have way different architecture than the access Catalysts and the previous Supervisors.

    Essentially, the new architecture is based on different hardware architecture. The good news is that it supports MQC and behaves more like router QoS, so the easiest solution for your problem would be to define a class-map with match-any criteria, then make it match different DSCP values that are of interest to you, and then apply that service-policy to input of the interfaces you'd like to monitor.

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Content dated before 7/24/2021 11:53 AM