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QoS, DSCP end-end support

It seems our DSCP values are being rest to default 0x00, when we define the access port to:

 mls qos trust cos
 auto qos trust

This applies to port conned to WAN routers, Firewalls and PCs running soft-phone applications (not Cisco). The Cisco IP Phone connected to a port defined as:

mls qos trust device cisco-phone

mls qos trust cos
 spanning-tree portfast

The DSCP values come out as EF 0x2e, si all good.

If I set the port to the WAN router and ASA firewall to, "msl qos trust DSCP", I can see the traffic passing from the WAN router to firewall with other than default DSCP default markings.

My questions are:

1) It this how you must configure the port to protest the DSCP settings?

2) What do the switches do with this data? I would hope it would process the low latency packets the same as COS 5 packets?

3) For PCs softphones, should I build policy maps similar to the Cisco Phone and apply them to the input ports?

4) Is there a source addressing this? It seems that everything is given in COS but that only exist in 802.1Q packets. The detailed control is in DSCP and the world has moved there but the Cisco documentation and examples are all in COS with very little given to DSCP. I thought would be the exact opposite.

We have large LAN and WAN networks that we need a better understanding on. The hardware spans from 2960S to Nexus 7Ks, router 29xx to ASRs.

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