My feeling is that to implement all these very fancy service models in the network is very very difficult. So, I think we should really simplify and have just two classes, may be CBR, and best-effort. In the CSRs it is better to implement just those two, and that is what has happened. Most of the ATM vendors have not really implemented all these sophisticated classes. They have implemented couple of classes, and that may be enough.
Application has to make a decision.
By this we are introducing a whole new dimension to the problem. If the network is doing something for us, and it can do it in a more cost-effective way, we should let it do it. There is an implicit assumption that video applications are VBR, and that is completely untrue. I think there is something that can fall in between, and that is there can be an entity which understands the models and which can interact with the application. It should not require every application to do renegotiation.