A Fault Tolerant Military Satellite Network Management System

This paper details the design of a truly fault tolerant, entirely computer controlled military Satellite Network Management System (SNMS). It covers the design goals, analysis, concepts, and architecture of this system. The first part of the paper discusses the requirements for fault tolerance in Defense Satellite Network control. It covers two aspects of fault tolerance: availability and integrity, along with their respective impact on Defense Satellite Network operations. Availability implies constant computer operation while integrity implies continuous correct system performance. Two distinct environments are then analyzed: network control centers and the remote earth stations. The paper discusses the unique requirements of each of these environments, both in terms of fault tolerance and functional requirements. It details the "transaction processing" oriented network control environment and the "process control" type environment of the remote earth stations. The two distinct design approaches required for each of the satellite network control environments are then examined. The design concept used for the military Satellite Network Control Center is examined first, consisting of a dual redundant data processing architecture. We discuss how this design fulfills the requirements of availability and integrity for the network control center. The paper covers indepth unique software developed to provide satellite network protection against operator-introduced errors. Next, the design of the remote earth station control systems is covered. In order to provide a fault tolerant control system for the earth station environment, an innovative approach is proposed. The chosen architecture is a "Triple Modular Redundant Voting" system.