1. If a egress packet has both Cos and Dscp setting, which map should this packet used to put into queue?
2. The 3750 is doing ip route. After the packet is routed, will the packet keep the DSCP and COS? Or it will just keep the DSCP and using the dscp-cos map to create a new COS.
Apologies for the confusion with the terminalogy.
The question is where you have configured the trust boundaries, do you necessarily trust the DSCP value prior to being routed across your network?
Therefore, although you have explicity trusted the DSCP value, do you still trust the value at the remote peer.
For example, you connect into an MPLS with QoS enabled, you know that the values you are trusting are correct within your network, however at the remote peer/branch they could be remarked by the provider. Therefore do you 'believe' the values, or do you simply not trust them and then reclassify on ingress.
Hope this makes sense..