If I were to put together a native-IP network (probably POS) which was running high levels of traffic (at least DS-3 to start and probably OC-3), and put services such as dial-up, hosting/co-locate, DSL, and high-speed dedicated, and mix in VoIP, is it feasible to use one IP pipe and logically segment it with IP QoS/CoS features?
You just described our network, and what several of our customers are doing. In other words, Yes. Now, it's not for blue haired ladies or non-innovative IT directors [translate to low risk tolerance]. But it absolutely is done today.
So far, it seems that the way to do this is to physically or logically segment the network using separate circuits or ATM. But it would make a lot of sense (in theory at least) to use IP and bunch everything together.
Bah. Keep listening to your ATM vendors... -a