We present a framework for scalable quality of service networks which would allow the network designer and network manager to cope with the uncertainties of network traffic and services and also at the same time simplify the overall network planning and dimensioning process. Our approach is based on decomposing the network by service and geography. The paper also discusses the role of optics in this framework and challenges that have to be addressed for the realization of such networks.

The authors present an analytical approach to the performance analysis of multihop lightwave networks with hot-potato routing and multiclass traffic. Explicit closed-form expressions are derived for the hop distribution and the probability of 'don't care'. The computational complexity is thus reduced as compared to previous approaches, and priorities are readily handled. Results for two different classes of traffic are given. The probability of a packet belonging to a particular class of traffic existing on a preferred path is calculated by finding the fixed point of a scale function. The throughput and network delay as well as queuing delay of a particular class are then calculated using the expressions derived for them.>

The achievable aggregate capacity for a variant of the basic multihop approach in which minimum distance store-and-forward routing is replaced by a hot-potato routing algorithm is determined. With hot-potato routing, all packets simultaneously arriving at a given node and not intended for reception at that node are immediately placed onto the outbound links leaving that node; if two or more packets contend for the same outgoing link to achieve a minimum distance routing, then all but one will be misrouted to links which produce longer paths to the eventual destination. Attention is confined to the development of an analytical methodology for finding the probability distribution of the number of hops with hot potato routing for symmetric networks under uniform traffic load. Results show that the maximum throughput achievable with hot-potato routing can be as low as 25% of that for store-and-forward routing, and that the relative degradation increases as the number of nodes grows larger. This implies that the link speed up needed to produce a significant overall capacity advantage with hot potato should be at least a factor of 10.>

A straightforward approach is found for computing the total aggregate capacity of a multihop network with hot-potato routing, and for finding the probability distribution of the number of hops taken by a representative test packet. The rows and columns of the state transition matrix used by this approach each contain, at most, two nonzero elements. The approach is valid for any symmetric network connection diagram under conditions of uniform loading. Results obtained for recirculating perfect shuffle connection diagrams show that the achievable aggregate capacity degrades relative to the capacity maximizing store-and-forward routing as the number of network nodes increases, but even for networks containing several thousand nodes, it is no worse than 25% of that for store-and-forward. Increasing the link data speed by more than a factor of four will produce, overall, a higher aggregate capacity.>