On Distributed Communications Series

VII. Tentative Engineering Specifications and Preliminary Design for a High-Data-Rate Distributed Network Switching Node


This Memorandum details the description of and the design specifications for the Distributed Adaptive Message Block Network Switching Node. Documentation is presented to verify that the necessary computer operations can be performed within the prescribed timing constraints of limited circuitry, and the equipment components count is determined.

The Switching Node is capable of operating at non-synchronous data rates of up to 1.54-million bits per second per link (with simultaneous input and output, and at a redundancy level of four). It would appear that such a Node can be built within the present state of the art, employing digital computer techniques.

Beyond the design specifications, it is shown that implementation appears feasible, and the details of a particular implementation scheme are provided. Feasibility calculations are given, upon which the designs are based, showing the manner in which the specifications were selected.

The approximate general characteristics of the Switching Node are as follows:

The anticipated system reliability appears to be satisfactory and well within the overall requirements for the network as a whole. Approximate initial equipment price--in production quantities, but not including research, development, and installation costs--could be on the order of $150,000 per unit, anticipating extreme care is taken in design production and in system management.

The format of Part One is that of a design specification, and is followed by an equipment implementation alternative (Part Two) which meets both the specification and the requirements established by digital computer simulations[1] of the overall system.

[1] As reported in Vols. II and III in the series.
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