Reducing electronic multiplexing costs in SONET/WDM rings with dynamicallychanging traffic

In this paper, we consider traffic grooming in WDM/SONET ring networks when the offered traffic is characterized by a set of traffic matrices. Our obj ective is to minimize the cost of electronic add/drop multiplexers (ADMs) i n the network, while being able to support any offered traffic matrix in a rearrangeably nonblocking manner. We provide several methods for reducing t he required number of ADMs for an arbitrary class of traffic matrices, We t hen consider the special case where the only restriction on the offered tra ffic is a constraint on the number of circuits a node may source at any giv en time. For this case, we provide a lower bound on the number of ADMs requ ired and give conditions that a network must satisfy in order for it to sup port the desired set of traffic patterns, Circuit assignment and ADM placem ent algorithms with performance close to this lower bound are provided, The se algorithms are shown to reduce the electronic costs of a network by up t o 27%, Finally, we discuss extensions of this work for supporting dynamic t raffic in a wide-sense or strict sense nonblocking manner as well as the be nefits of using a hub node and tunable transceivers, Much of this work reli es on showing that these grooming problems can often be formulated as stand ard combinatorial optimization problems.