Cat 4500 : cannot apply input service policy

Answered Question
Mar 14th, 2008
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I am having a problem applying an input service policy to a port on a 4500. I want to use a policy-map to mark traffic at the edge. The policy-map is OK, and all its classes are OK. I can apply it to the port on some of my 4500 switches, but not on others.


The only difference I can see is that on the switches were I can apply the service policy, I have ip routing enabled. On switches were ip routing is not enabled, when I try and apply the service policy it simply does not apply it, and it does not go into the config.


Does this mean I can apply a service policy only on switches that have layer-3 routing enabled? What if I want to mark traffic coming into a port on a 4500 used as a layer-2 access switch?


What am I doing wrong here?


Kevin Dorrell

Luxembourg

Correct Answer by Jon Marshall about 9 years 1 week ago

Hi Kevin


From the 4500 configuration guide


=============================================


If you want to use the set command in the policy map, you must enable IP routing (disabled by default) and configure an IP default route to send traffic to the next-hop device that is capable of forwarding.


=============================================


Full link here:


http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/25ewa/configuration/guide/qos.html#wp1225544


HTH


Jon

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Correct Answer
Jon Marshall Fri, 03/14/2008 - 11:49
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Hi Kevin


From the 4500 configuration guide


=============================================


If you want to use the set command in the policy map, you must enable IP routing (disabled by default) and configure an IP default route to send traffic to the next-hop device that is capable of forwarding.


=============================================


Full link here:


http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/25ewa/configuration/guide/qos.html#wp1225544


HTH


Jon

Kevin Dorrell Sat, 03/15/2008 - 10:59
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Jon,


Thanks for finding that. It seems a very strange constraint. We use 4503s in the wiring closet as layer-2 access switches, and of course that is precisely where we want to mark our telephone traffic.


Unfortunately, our non-Cisco telephone equipment marks the traffic ... shall we say ... unconventionally. I want to mark it with the standard EF and CS3 PHBs before it gets into the distribution layer.


It seems strange constraint to have to enable IP routing just to remark the DSCP. After all, a 2950 with EI can do it, and that is only a layer-2 switch. These switches only have one SVI, and that is on the management VLAN.


I wonder why.


Kevin Dorrell

Luxembourg


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