Comparison of Capacity Efficiency of DCS Network Restoration Routing Techniques
Robert Doverspike
AT&T Labs (Research) - Room A177
180 Park Avenue, Bldg 103
Florham Park, NJ 07932-0971
Email: rdd_AT_research.att.com
Brian Wilson
Bellcore
331 Newman Springs Rd
Red Bank, NJ 07701
Email: brian2_AT_bellcore.com
Abstract
A crucial issue in the management of telecommunications networks is
restoration after a network failure. We compare the capacity efficiency (the
amount of traffic restored over fixed capacity) of several types of
restoration methods for Digital Cross-connect Systems (DCSs) under both node
or link failures in metropolitan networks. These restoration methods can be
broadly categorized based on the type of control of the restoration process
and the type of procedure for rerouting traffic around
the failure. It is easily shown that point-to-point methods (where traffic
is rerouted end-to-end) restore a higher percent of traffic than patch methods (where
traffic is rerouted only around the failed segment). However, quantification of the
difference in efficiency among the methods is important to fully evaluate
other trade-offs, such as cost and speed of restoration. To evaluate the
efficiency difference, we generated random network traffic distributions
by simulation and then failed links and nodes for each simulation sample.
Statistics were generated on the expected amount of restored traffic for each restoration
method. In particular, we found that the efficiency advantage of point-to-point
methods over patch methods is greater for link failure than for node failure.
Also, the difference was not statistically significant in low levels of
network congestion (i.e., networks with large amounts of excess capacity)
and became more significant as network congestion increased.
Keywords: Network Restoration; Digital Cross-Connect System (DCS); routing algorithms; multicommodity flow
JNSM: Vol. 2, No. 2, 1994
Comparison of Capacity Efficiency of DCS Network Restoration Routing Techniques [Vol. 2, No. 2, 1994]
NOTE: only abstract of paper available on-line
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