QoS classification problem, please help someone !

Unanswered Question
Jan 31st, 2007

Hi all,

by the time writing this I am really bitter of fighting against something unvisible.

As a first step of qos implementation I just want to classify some traffic - any traffic - on a Catalyst 3560 ingress port for further processing. This is the first step, and even though a really simple configuration, it does not work.

Please, someone tell me what else is needed than :

- enable qos globally on the switch

- write a simple acl, like "permit ip any any"

- create a class map, match all and use

this acl as a match criterion

- create a policy-map, assign the class map previously created, and explicitly set the dscp value of the packet

- assign this policy-map to an interface, direction input

After these configuration applied, should I not see

- acl match counter greater than 0 ?

- policy map counters on the relevant interface greater than 0 ?

- egress packets marked dscp values other than 0 ?

I have been trying to get along with it for a very long time, and now it gets on my nerves.

What am I missing ??? Please...

I have this problem too.
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pciaccio Wed, 01/31/2007 - 12:33

I do not know your network topology, however I too have seen this and realized that the traffic that I classified does not pass through the interface that I placed the policy on. The switch was performing fast switching and the packets never went through the interface....

franklaszlo Wed, 01/31/2007 - 12:44

nice trap, but in my case this cannot be the problem. There is a mail gateway directly attached to the switch on two ports and emails are continously flowing through it. On the other hand, as a last resort, I set up the ACL really as "permit ip any any" !

pciaccio Thu, 02/01/2007 - 03:33

So if you have a mail gateway on the switch between two subnets then what is the interface off the router being used for. Is the traffic actually going through the interface of the router or is it all going through the gateway? If going through the gateway then how is the traffic being classified by the router interface?

franklaszlo Thu, 02/01/2007 - 04:45

Ok, I'll try to make a simple sketch :

I Catalyst 3560

I Gi 0/7 Gi 0/8

I---I----------I-----

I I

I I

I---I----------I-----

I Incoming Outgoing

I

I Symantec Mail Security

SMTP traffic flows in to SMS on Gi0/7

and leave it on Gi0/8.

Sometimes SMTP traffic increases above a limit and then other traffic suffers from this. Therefore, I want to classify SMTP traffic to a lower dscp value than other traffic, and set up a queuing strategy accordingly.

h.parsons Thu, 02/01/2007 - 11:10

Are you using the Command: "show policy-map interface"

If you are this may be why you dont see anything on your policy-map counters. This is a note out of the config guide.

Note: Do not use the show policy-map interface privileged EXEC command to display classification information for incoming traffic. The interface keyword is not supported, and the statistics shown in the display should be ignored.

franklaszlo Thu, 02/01/2007 - 11:26

Hello,

yes I do use it, and I just cant believe my eyes, is that possible ? I read both the Cisco Press BCMSN and the router's config guide but I did not note it. Then how can I check if it works ?

On the other hand, not just those counters are 0, but also the class-map's match ACL's counters. By the way, the "sh mls qos int gi 0/7 stat" command also produces ambigous results.

Is this still a normal op ?

Many thanks,

Laszlo

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