mls qos command

[tedauction]

Hello, I have QoS setup on my C2960X-48FPD-L stack. I can confirm my QoS config is correct as it is identical to another switch in production.

I enabled QoS using the command 'mls qos' however when I run 'sh policy-map interface' I just get all zeros i.e .QoS does not seem to be working at all.

Is there anything else I have to do to activate QoS apart from the command 'mls qos' ? i.e.do I need to reboot the switch or shut/no shut interfaces ?

Thank you kindly.

[Mark Malone · Accepted solution]

Hi

That's not the right command to check MLS QOS use this....sh mls qos interface g1/0/1 statistics

That's a L3 command your using with policy maps or auto qos command depending on setup

[tedauction]

Hello, thanks but I am actually using custom policy maps in my configuration.

The IOS version is C2960X-UNIVERSALK9-M.

Does 'sh policy-map int' show blank because QoS is performed in hardware rather than software ?

What command would I use to see results of the policy-maps.

[Mark Malone · Accepted solution]

Ok but if your using custom policies your not using MLS qos as its layer 2 qos that does not use policy maps , auto qos or MQC qos uses policy maps , MQC must be applied to layer 3 interfaces, auto is layer 2 and automatically builds a policy map and class maps that can be tweaked 

[tedauction]

Thanks kindly, so if I am using MQC (custom policy maps), then do I still need to have 'mls qos' activated ?

Or is it one or the other ?

Also are you saying I cannot enter the command 'service-policy input Marking' on a L2 interface that is a VLAN assigned interface i.e. do this command have to go on the SVI for that VLAN instead ?

Thank you for your assistance.

[Mark Malone]

You can still have MLS qos trust dscp on any edge ports for layer 2 MLS qos,MQC is L3 qos , if the switch is not under any pressure though L2 qos isn't really a requirement and you should be careful with layer 2 qos and monitor when first deployed make sure it's not causing issues but generally works well on its own 

[tedauction]

Thanks Mark.

I simply detecting VoIP traffic and marking as EF with my service-policy.

I have turned off mls qos.

Is this going to work well enough for me ?

Thank you kindly.

[Mark Malone]

Really you need to test it when you have it deployed it should be enough once its done correctly , make sure your policy map is not dropping packets in the EF queue for priority

And if this switch is trunking you don't need a service policy but rather MLS qos as its layer 2 , but if you have a circuit coming off this switch like a layer 3 port then use service-policy

so if switch is layer 2 use layer 2 qos you don't need custom policys , they would usually be used on  your WAN interface on your router facing your ISP

im saying this as I see your other post saying your applying to an SVI is that for a circuit or a standard SVI with layer 2 ports , if so I would use MLS qos instead , can you post your custom policy to see why you might need something like that as MLS covers all dscp values and voice packets will be put in priority queue at layer 2 if that's what you require to make sure its prioritized

MLS splits the interface into 4 queues with 1 of them being the most priority and serviced first when set

Also I would wireshark a few ports and make sure there marking packets correctly using a SPAN session  , you want your phones to be marking as EF

example

  Service-policy : xxxxxxxxxxxx

        queue stats for all priority classes:
          Queueing
          queue limit 512 packets
          (queue depth/total drops/no-buffer drops) 0/0/0
          (pkts output/bytes output) 1118014/218340662

[Joseph W. Doherty]

Cannot say for sure for a 2960X, but if it's like earlier 2960s, and 3560/3750, there's only limited support for policy-map QoS.  Most, if not all, egress QoS is bound up in the hardware, with different configuration statements to support.  MLS QoS enables hardware QoS, with default settings.

See your software's version configuration guide for QoS.