Brian E Carpenter wrote: > I have to agree that e2e cannot create network level QoS that isn't > available - > if the best path available can't offer the desired QoS, no end system > magic can > achieve that QoS. But it can at least make the best use of the QoS > available, > e.g. by reducing a streaming data rate to avoid random loss. The problem is that the meaning of "end" varies. For example, with mobility, a home agent is an end and with multicast, some entity which manages a group is an end (which is why dense mode multicast with no such entity does not scale). As for QoS, it can be said that all the intermediate routers are ends. In a sense, systems on a path between a source and a destination may be ends, as long as the path is determined dynamically and the systems hold dynamic state only, because the systems have proper knowledge on the ongoing communication. In a sense, "end" means a system with proper knowledge and control on the ongoing communication. For example, as for QoS, PDP, which definitely is not "end" with limited knowledge and control, destroyed E2E property. Masataka Ohta _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf