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Classifying traffic on a 3750 - what am I doing wrong?!

Unanswered Question
Nov 22nd, 2006
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I have the following on a 3750:


class-map match-any critical

match ip dscp ef

class-map match-any priority

match access-group 181

!

!

policy-map classify-traffic

class critical

trust dscp

class priority

set dscp af31


access-list 181 permit tcp any any eq 3389

access-list 181 permit tcp any any eq telnet


!


I can attach the policy map to the ingress of both vlan interfaces and physical ports.


BUT it doesn't appear to be doing anything, as I get these results:


#show policy-map int

Vlan1


Service-policy input: classify-traffic


Class-map: critical (match-any)

0 packets, 0 bytes

offered rate 0 bps, drop rate 0 bps

Match: ip dscp ef

0 packets, 0 bytes

rate 0 bps


Class-map: priority (match-any)

0 packets, 0 bytes

offered rate 0 bps, drop rate 0 bps

Match: access-group 181

0 packets, 0 bytes

rate 0 bps


Class-map: class-default (match-any)

0 packets, 0 bytes

offered rate 0 bps, drop rate 0 bps

Match: any

0 packets, 0 bytes

rate 0 bps


Also, when I do a show mls qos int stat, no traffic is being marked as either ef or 31.


Any ideas what I'm doing wrong? There is definitely traffic so something should be showing up.


Please help!


Thanks,

J






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Overall Rating: 4 (3 ratings)
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zubairjalal Wed, 11/22/2006 - 02:21
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For the counters in the access-list and the class-maps, this is normal as PBR in the cat3750 is implemented in hardware/TCAM, so packets are not switched through software (unless there are exceptions like the PBR policy configuration does not fit in the TCAM, or the next hop adjacency has not been resolved, etc).


The class map counters only reflect the packets switched in software (interrupt or process context). The hardware switched policy routed traffic will not increment the class-map counters, this is primarily driven due to the limited amount of hardware statistics buckets available.


--Pls rate if this helps---


jigsaw2026 Wed, 11/22/2006 - 02:50
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Many thanks zubairjalal. I guess it could be working then....is there any way of actually checking?

sourabhagarwal Wed, 11/22/2006 - 03:09
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  • Gold, 750 points or more

check for the interface on which policy map is applied and see if it is getting congested or not.


you have configured CBWFQ as QoS, created policy map and applied it to the interface. This QoS will be in effect only when interface on which this policy is applied is experiencing congestion.


If there is congestion on the interface then only the traffic will be given precedence as config in policy maps and then you can see the counters incrementing.


rate if it helps ...



danielmassey Wed, 11/22/2006 - 02:35
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Hello J,


Once the Qos we need to specify the Policy Map to the interface we want to implement.


Please try this command in the interface where u wanna Implement QOS:


service-policy input/output classify-traffic


Hope this will help. Please rate me.


http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800c75d0.html


Regards

Danny

jigsaw2026 Wed, 11/22/2006 - 02:51
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Hi Danny,


Thanks for your response - sorry I should have made myself clearer, I have already entered the service-policy input command on the interface.

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