I don't have an answer, but I am sure interested in finding out if you do.
We are looking at Riverbed, and like you we don't manage the WAN routers (our WAN supplier does) So being able to add QoS "over the top" via Riverbed for VoIP is an attractive proposition.
CBQoS is a Cisco-specific technology.
I should have known. Sometimes I hate managed networks.
hwangeruk, give riverbed a shot, netflow works perfectly with solarwinds (other than QoS, but that's not a SW issue).
And I do recommend the SH appliances over other vendors. We are doing QoS on them for limiting bandwith and prioritizing traffic and it works great.
QoS works perfectly with SHAs, especially when you're using the same CoS values than your provider and when you've paid for the service.
If you already have the agreement of your provider, select the WAN int. of your appliance for the Netflow "captures", the DSCP values are seen only on the WAN flows (between the 2 SHA) as they are supposed to be handled by the WAN routers.
Regarding the prioritization, I think it's the best way to avoid paying for the QoS service of your provider (but you need to be sure that it provides enough bandwidth on its backbone).
The main issue is that Steelhead appliances are only handling only the TCP traffic, so there is no benefit for T/VoIP traffic (UDP).