Testing the Isotach Prototype Hardware Switch Interface Unit

Abstract

Although Isotach systems can be implemented entirely in software using commercial off-the-shelf hardware, they achieve greatest efficiency with the help of special hardware components, one of which is the switch interface unit (SIU). Located in-link between the network interface boards and switches to which these boards are connected, the SIU is responsible for the maintenance of logical time, for timestamping outgoing isotach messages, and for exchanging tokens with another custom hardware device, the token manager (TM). <P> Testing the SIU requires the modification of the isotach prototype code base to create two new system versions, Version 1.75 which emulates the functionality of the SIU and is intended to run in systems in which other nodes are connected to hardware SIUs, and Version 2 which runs on hosts connected directly hardware SIUs. In addition to these prototypes, a suite of test programs has been designed to aid in lower level debugging of the device, and to verify that design requirements have been met. <P> This technical report describes the development of these prototype versions, the current state of the SIU debugging process, and the design of the test suite. In addition, detailed prototype code documentation and hints for programming the LANai (the Myrinet network interface processor) are included in the appendices.