Performance and reliability of DQDB metropolitan networks under faults

The authors investigate the performance and reliability of a DQDB (distributed queue dual bus) metropolitan area network under intermittent and stuck-at-fault nodal error conditions. The analysis is repeated with triple modular redundancy and quintuple modular redundancy applied to specific circuitries with the network node. The Weibull model is used to investigate the degradation of the network due to a single falling node. The results show these circuits within the user node where forward error correction gives a greater immunity of the whole network against faults. The authors clarify the close interaction between the network multiprocess protocol and the error sensitivity of various circuits and the aging effects of circuits on the performance, which affects the renewal rate. It is pointed out that this provides an entirely new concept and criterion for selecting protocols for wideband ISDN (integrated services digital network) networks