The preliminary hardware description of CHOPP (Columbia Homogeneous Parallel Processor), a MIMD machine supporting a fully distributed host-less operating system is presented. The architecture is intended to permit implementation of machines with 10 5 to 10 6 processors. Issues of interconnection networks, throughput, and memory structure are treated.

approach and might prove difficult to adapt to This paper proposes an architecture for accomplishing transport protocol processing at Gbps rates. The limitations of currently used transport protocols have been analyzed extensively in recent literature. Several benchmark studies have established the achievable throughput of IS0 TP4 and TCP to be in the low Mbps range; several new protocols and implementation techniques have been proposed to achieve 100 Mbps and higher throughput rates. We briefly review some of these protocols and establish the need for a radically different approach to meet our objective.An estimate of the aggregate processing power required for Gbps throughput is developed. It is proposed that a cost effective and practical solution to the processing requirements could be based on a multi-processor system. The opportunities for parallel processing in a typical transport protocol are examined.Several alternate parallel processing approaches are examined and arguments are advanced for selecting a favored approach.A corresponding parallel processing architecture is described. Data structures used to preserve packet ordering and techniques for reducing contention in a multi-processing environment are discussed. An implementation methodology for conventional transport protocols (e.g. TP4) is outlined. Some suggestions are made for improving efficiency by making modifications to the protocol that do not compromise functionality. The performance achievable with thii modified architecture is analyzed and some suggestions for further work are presented. changing needs. The other approach is to take a fairly general multi-processing platform and customize it to the needs of a particular transport protocol. We shall establish that not only is the latter approach feasible, but is also achievable at a relatively modest cost. We assume that the protocol processing up to (and includiig) the transport level is performed in a dedicated frontend system that is connected to the host computer by a high-speed interface and that all higher level processing takes place in the host or other satellite systems.Several articles have appeared in recent literature dealing with applications of parallel processing to protocol impl.emcntation. An excellent analysis of the opportunities for parallel processing withii a protocol layer appears in [8]. The concept of division into horizontal and vertical sub-layers is discussed and illustrated with specific examples of application to TP4 and other protocols. In [9]. the authors discuss several possibilities for parallel processing within the transport layer. One of these is to view the protocol as a composition of state machines which can be implemented on distinct processors. In this paper, we describe a somewhat different approach based on processing packets in parallel which seems to offer more potential for speed-up.

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Intended ApplicationsThe present paper complements the hardware proposal for a fully distributed parallel processor presented in "A Large Scale, Homogeneous, Fully Distributed Parallel Machine, I, " by describing a suitable software structure for its operating system management. It is shown that the most basic operating system functions can be performed on a purely local basis, i.e. in such a fashion that identical pieces of the operating systems are concurrently executed by each of the processing elements.