Reducing Electronic Multiplexing Costs in Sonet/wdm Rings with Dynamically Changing Traac 1

In this paper we consider traac grooming in WDM/SONET ring networks when the ooered traac is characterized by a set of traac matrices. Our objective is to minimize the cost of electronic Add/Drop Multiplexers (ADMs) in the network, while being able to support any ooered traac matrix in a rearrangeably non-blocking manner. We provide several methods for reducing the required number of ADMs for an arbitrary class of traac matrices. We then consider the special case where the only restriction on the ooered traac is a constraint on the number of circuits a node may source at any given time. For this case, we provide a lower bound on the number of ADMs required and give conditions that a network must satisfy in order for it to support the desired set of traac patterns. Circuit assignment and ADM placement algorithms with performance close to this lower bound are provided. These algorithms are shown to reduce the electronic costs of a network by up to 27%. Finally, we discuss extensions of this work for supporting dynamic traac in a wide-sense or strict sense non-blocking manner as well as the beneets of using a hub node and tunable transceivers. Much of this work relies on showing that these grooming problems can often be formulated as standard combinatorial optimization problems.