As the number of processor cores and IP blocks integrated on a single chip is steadily growing, a systematic approach to design the communication infrastructure becomes necessary. Different variants of packed switched on-chip networks have been proposed by several groups during the past two years. This book summarizes the state of the art of these efforts and discusses the major issues from the physical integration to architecture to operating systems and application interfaces. It also provides a guideline and vision about the direction this field is moving to. Moreover, the book outlines the consequences of adopting design platforms based on packet switched network. The consequences may in fact be far reaching because many of the topics of distributed systems, distributed real-time systems, fault tolerant systems, parallel computer architecture, parallel programming as well as traditional system-on-chip issues will appear relevant but within the constraints of a single chip VLSI implementation.

We consider flow control algorithms consisting of two parts: quasi-static flow control and dynamic flow control. The quasi-static part uses short term average information on network utilization to allocate maximum data rates and to determine routes for each user. The rates are allocated to achieve an optimal trade-off between assigned priority cost functions for each user and the cost of congestion in the network. This optimization can be done by a distributed algorithm and is essentially no more complicated than optimizing routing alone. The dynamic flow control has the function of admitting or rejecting individual units of traffic into the network so as to enforce the maximum allocated rates and to prevent congestion by smoothing out the fluctuations in buffer occupancy. (Author).

We consider a model of integrated voice and data networks. In this model the network flow problem is formulated as a convex optimization problem. The objective function comprises two types of cost functions: the congestion cost functions, which limit the average input traffic to values compatible with the network conditions; and the rate limitation cost functions, which ensure that all conversations are fairly treated. A joint flow control and routing algorithm is constructed which determines the routes for each conversation, and effects flow control by setting voice packet lengths and data input rates in a manner that achieves optimal tradeoff between each user's satisfaction and the cost of network congestion. An additional congestion control protocol is specified which could be used in conjunction with the algorithm to make the latter respond more dynamically to network congestion. (Author).

This paper considers a model of an integrated voice and data network. The model, which lends itself to analytic and algorithmic solution, is formulated as a convex optimization problem. The objective function comprises two types of functions: the congestion cost functions and the rate limitation functions. The congestion cost functions act to limit the average traffic entering into the network to values that would not cause network congestion. The rate limitation functions ensure that all conversations are fairly treated. The model can be generalized to solve problems of networks which handle n types of traffic that have different levels of delay sensitivity, where n> or = 2. A joint flow control and routing algorithm is constructed which uses short term average information on the network utilization to set the voice packet lengths and data input rates, and to determine the routes for each conversation. The voice packet lengths and data input rates are set in such a way as to achieve an optimal tradeoff between each user's satisfaction and the cost of network congestion. Additional protocols are specified for dealing with such issues as congestion avoidance and control, and for implementing flow control on a more dynamic basis than the quasi-static joint flow control and routing algorithm can handle.

This volume is a compendium of papers presented during the NATO Workshop which took place in Capri, Italy, October 12-18, 1986 on the general subject of "Flow Control of Congested Networks: The Case of Data Processing and Transportation", and of which we acted as co-chairmen. The focus of the workshop was on flow control methodologies, as applied to preventing or reducing congestion on: (1) data communication networks; (2) urban transportation networks; and (3) air traffic control systems. The goals of the workshop included: review of the state-of-the-art of flow control methodologies, in general, and in each of the three application areas; identification of similarities and differences in the objective functions, modeling approaches and mathematics used in the three areas; examination of opportunities for "technology transfers" and for future interactions among researchers in the three areaso These goals were pursued through individual presentations of papers on current research by workshop participants and, in the cases of the second and third goals, through a number of open-ended discussion and-review sessions which were interspersed throughout the workshop's programmeD The full texts or extended summaries of all but a few of the papers given at the workshop are included in this volume.