Resource Management for Fault Tolerant Path Structures in Ring-Based Networks [Vol. 7, No. 4, 1999]

Resource Management for Fault Tolerant Path Structures in Ring-Based Networks

Wayne D. Grover
c/o TRLabs,
#800 Park Plaza,
10611-98 Ave.,
Edmonton, Alberta,
Canada, T5K 2P7
Email: grover_AT_trlabs.ca

Abstract
There is growing interest on the part of network operators in the ability to analyze the availability of path implementations in their networks and to provide various grades of assured service availability to customers. The calculation of availability is, however, considerably more complex in today's SONET (soon also WDM) ring-based networks than in prior point-to-point systems. This is due both to the active protection nature of the rings and their dual - redundant interconnect strategies. We show that there is also more than one option for dual-ring interconnection and that a minimum cost high availability path implementation will generally involve a mixture of matched-node and explicit dual fed path treatments. We develop an economic comparison of dual feeding (df) and matched nodes (mn) in terms of the resource consumption of each scheme and show that the choice can be made on an individual ring-by-ring basis with a simple decision criterion. We then develop expressions of general use for the end-to-end unavailability of single-fed, pure df, pure mn, and mixed df-mn path constructions. These results are a step towards on-line provisioning or path planning systems that can minimize the path implementation cost subject to an assured target level of design availability.

Keywords: fault tolerance, survivable networks, SONET rings, WDM rings, matched nodes, dual ring interconnect, availability, path provisioning

JNSM: Vol. 7, No. 4, 1999 Resource Management for Fault Tolerant Path Structures in Ring-Based Networks [Vol. 7, No. 4, 1999]

NOTE: only abstract of paper available on-line; please contact your library or the authors for the full paper

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