Efficient Network QoS Provisioning Based on per Node Traffic Shaping

We address the problem of providing per-connection end-to-end delay guarantees in a high-speed network. We assume that the network is connection oriented and enforces some admission control which ensures that the source traffic conforms to specified traffic characteristics. We concentrate on the class of rate-controlled service disciplines, in which traffic from each connection is reshaped at every hop. The main disadvantage of this class of service disciplines is that the end-to-end delay guarantees are obtained as the sum of the worst case delays at each node. In this paper, we show that this problem can be alleviated through ``proper'' reshaping of the traffic, and derive end-to-end bounds for the general case of arbitrary reshaping at each hop. We establish that these bounds can also be achieved when all hops use the same shapers which, in order to achieve good delay bounds, are in general different from the original envelope of the source traffic. We illustrate the impact of this reshaping by demonstrating its use in designing rate-controlled service disciplines which outperform GPS-based service disciplines. Furthermore, we show that we can restrict the space of ``good'' shapers to a family which is characterized by only one parameter. We also describe extensions to the service discipline that make it work conserving, and as a result reduce averag..