Supervisor 8E QoS

[eagles-nest]

Hi

Could anyone point me to a decent document covering QoS on the Sup 8E ports?  Specifically the 10Gb/s onboard ports when used in an etherchannel ?

Auto qos seems to generate appropriate config for the 1Gb/s modules but I can't find any good documentation for the onboard ports on the Sup8E.

Many thanks, Stuart.                  

[eagles-nest]

Ok.  Is it me or is this 4500 QoS on channels a complete dogs dinner ?

Every time I try to configure something IOS complains about something or other.  The latest I have is a policer on the port channel interface.  Nice and simple to start with because it doesn't like CoS and DSCP in the same class.  So I have the following and I apply it to the Po1 interface and IOS is ok with it.

class-map match-any Priority-q

match dscp ef

!

policy-map channel-interface
class Priority-q
  police cir 2000000000

!

interface Po1

service-policy out channel-interface

I try to do a bandwidth reservation for a signalling class and IOS says no way.  Like no one would want  to police a priorty queue and give another queue a bandwidth.

I look at the counters with some EF traffic going through the interface and I'm seeing stuff.

So I try to apply queues to the physical interfaces.  And I try to sneak in a bandwidth for signalling and it takesthe config below.  Looks promising.

policy-map channel-member

class Priority-q

  priority

class signalling

  shape average 20000000000

interface Te3/1

service-policy out channel-member

It takes it.  Looking good.

So I look at my Te3/1 counters and there's nothing in any class apart from class default.

Whatever happened to shaped and shared queues ?  No doubt I'm missing some simple fundamental aspect here where I can easily ship my EF stuff through my priority queue on an etherchannel and see it doing so and guarantee my signalling traffic a bit of bandwidth.

Stuart.

[Tinya Cheng · Accepted solution]

Hi Stuart,

The configuration guide for the Sup8E running 3.3.0XO (the only available version at this time) is here:

http://www.cisco.com/en/US/partner/docs/switches/lan/catalyst4500/XE35.0XO/configuration/guide/qos_mrg.html

Sup8E uses MQC QoS. This allows for more granularity, but at this time, AutoQoS is not supported on etherchannels. This is due to the QoS architecture of the Sup8E (which is similary to the 4500, Sup6E, and Sup7E), where queueing functions must be placed on the physical member of the etherchannel and non-queueing functions (such as policing and marking) must be placed on the logical etherchannel interface.

This is documented in the configuration guide and the following caveat:

https://tools.cisco.com/bugsearch/bug/CSCsq67430/

[eagles-nest]

Thanks Tinya

I found an interesting point in the document at that URL you supplied.  It says

"When a policy-map is attached to a port-channel member ports, classification statistics are not displayed."

So for QoS on an etherchannel it is effectively saying you can attach the policy but there is no way to confirm traffic is being matched and queued properly.  You just have to trust it does so ?

I'm not too sure that will go down well with customers.  Say we have a voice issue.  The 1st thing I would look at would be the priority queue stats.  In this case I will see nothing in the stats for that or any other interface specific class.  I can see the cumulative matches on my port channel interface policer but that doesn't confirm to me that they are getting priority.

Strangely I have found a way to see these stats on the interface level but the Cisco docs say it's not supported and even though it works when I reboot or un-apply and re-apply the policy it fails to apply.

I think the message here is trust that the interface policies are doing what they say.

Thanks again, Stuart.