The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	The postbus fault tolerant CLOS network
Author:	Sarangapani, Udayabhanu
View Online:	njit-etd1993-139 (ix, 37 pages ~ 1.7 MB pdf)
Department:	Department of Electrical and Computer Engineering
Degree:	Master of Science
Program:	Electrical Engineering
Document Type:	Thesis
Advisory Committee:	Carpinelli, John D. (Committee chair) Ziavras, Sotirios (Committee member) Palis, Michael Abueg (Committee member)
Date:	1993-05
Keywords:	Fault-tolerant computing Computer architecture
Availability:	Unrestricted
Abstract:	The trend in modern computing is to develop multiprocessor systems with hundreds, even thousands, of processors and memory modules. The task of providing communication paths among all these units is not a trivial one. For a small number of functional units, direct connections could be used but for large systems interconnection networks have to be used. Multistage Interconnection Networks (MINs), provide a dynamic means for interconnecting processors and memory in a multiprocessor system. These networks are built with switches in each stage. The Clos network is a well defined family of MINs and consists of three stages. The ordinary Clos network has no fault tolerance capability. This thesis work presents the design for a modified Clos network by incorporating hardware redundancy. The excess hardware is in the form of an extra switch in the middle stage, demultiplexers and multiplexers in the outer stages and two sets of buses. Algorithms are developed to set the states of the demultiplexers and multiplexers. It is shown that the proposed design is able to withstand one faulty switch in each stage and still retain the property of full recovery, i.e., the network is still able to realize any given input-output permutation.