6500 MPLS 802.q trunk port trust state

Unanswered Question
Jun 10th, 2010


I am trying to figure out what trust state to set on a Gig Ethernet port
on a Cat 6500. The 6500 is running MPLS.

The port is an 802.1q trunk that is carry IP packets and MPLS packets.

I want to trust the DSCP of the IP packets and the EXP of the MPLS packets.

Any views as to what the trust state should be set to?


I have this problem too.
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Giuseppe Larosa Thu, 06/10/2010 - 10:06

Hello Phil,

if the port is an 802.1Q trunk you should match CoS that is present in all frames and should be a copy of upper layer IP Prec or MPLS EXP

CoS is in 802.1p that is part of 802.1Q

the only issue would be with native vlan if untagged (as default) avoiding to use the native vlan or setting it to a non used vlan-id on both ends of the link can be a correct move

Hope to help



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