QoS Tagging

bolshoi.88 · ‎05-08-2009

Hi,

Would it be possible that a QoS tagging is lost as it traverses between directly connected interfaces of two switches.

What possible reason a dscp marking is stripped on the ingress interface?

Thanks.

Collin Clark · ‎05-08-2009

The only way I can think of is if you remapped the markings, which I don't think is possible ingress on a layer 2 switch.

andrew.prince · ‎05-09-2009

If you have "mls qos" enabled - BUT you want to keep the DSCP value in the IP header and NOT have the switch re-write it according to it's internal DSCP mapping tables then configure:-

"no mls qos rewrite ip dscp"

By default a switch WILL re-write and DSCP/COS values unless told not to.

HTH>

bolshoi.88 · ‎05-09-2009

Thanks guys. Would there be service interruptions when you apply this commands?

Thanks.

andrew.prince · ‎05-09-2009

I have not seen any service interruptions when applying this config.

HTH>

bolshoi.88 · ‎05-11-2009

Hi,

Can this applied to a Cisco 4500?

Any equivalent command?

Thank you.

bolshoi.88 · ‎05-11-2009

Is this the same as no qos rewrite ip dscp?

thank you.

andrew.prince · ‎05-11-2009

Yes.