[c-nsp] Simple Marking DSCP based on source

[Jeff Kell]

I have an unusual case for some (hopefully) simple DSCP marking on a 6500...

We use a traffic shaping device to both prioritize certain traffic
within our network as well as smartly police traffic to match our ISPs
contracted bandwidth limitations.  The device is a few hops away from
our border router, but is BGP-aware, and uses the ASpath information to
classify traffic by provider (for bandwidth limiting).

Unfortunately, the ASpath view is only accurate for outbound traffic. 
Based on actual border interface traffic versus the "calculated" ISP
traffic on the device, there are considerable differences (our BGP view
of course doesn't dictate how the traffic actually arrives).

I would like to DSCP-mark traffic at the border, pass it down to the
shaping device, where it can use the DSCP value to differentiate ISP
traffic inbound, and shape accordingly. 

One ISP is point-to-point, and I can 'mls qos cos x' to mark that by CoS
and let that propagate/map to DSCP.

The other two are coming in on trunks, and you can't 'mls qos cos' on an
SVI.

Is there a relatively straightforward way to accomplish this "source
ISP" marking?

Jeff