Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

QOS on CAT 6500

Can somebody verufy this for me..In CAT 6500 at the PFC level a default QOS acl (that resets DSCP=0) is applied to each frame, as a result any non zero DSCP traffic like control and routing traffic is forwarded at a reduced priority (with DSCP=0) through the PFC and to the output port ?

New Member

Re: QOS on CAT 6500

When you enable QoS, the default behaviour will be like this for all packets. If you want to retain the dscp when u enable QoS, you may have mark the incoming port as trusted one. Then the DSCP will be preserved.

If you are not using any QoS features, then you can disable QoS at the global level. This will pass the pass the packets as is w/o modifying any of the DSCP values.


New Member

Re: QOS on CAT 6500


I Have a Similar issue. I have a 6509 with a Sup720. I have a voice gateway connected to one of the Ethernet port and a phone on the other port. When I make a call into the Voice Gateway the packets are marked with the right DSCP Values. I have tested this with a network sniffer. But as they are routed through the Sup 720 the DSCP Values are stripped of. This only seems to apply to the RTP UDP Stream. The TCP Stream is Left Alone. I have set the trust command on the Ports I am using.

Any ideas.