Dynamically reconfigurable logical topologies for fiber optic LAN/MANs

Abstract

The large bandwidth, in the range of tens of Terabits/sec, capacity of optical fiber made it an obvious choice for transmission medium of emerging and future networks. However, as the electronically operated computing nodes can not process information at these rates, network architectures must be designed to allow parallel transmissions among the computing nodes by dividing the bandwidth of optical fiber into multiple channels. Multichannel multihop architectures use Wavelength Division Multiplexing (WDM) for concurrent transmissions at the (order of Gigabits/sec) speeds of computing nodes. The nodes in these networks communicate using a predefined connectivity pattern called logical topology. The LAN/MAN architectures usually employ a regular topology as nodes interconnectivity pattern. This thesis expands upon the multichannel multihop LAN MAN architectures based on regular topologies and considers the use of reconfiguration as a regular topology design issue for tolerating changes in the network such as node failures and additions. By assuming a regular structure of larger size as a base topology wherein each node in the network occupies a unique position, reconfiguration is defined as changing the links of the neighbors of failed/ added node so that the resultant structure remains connected. We call this reconfiguration as local perturbations and the topologies designed using local perturbations as reconfigurable topologies or perturbed topologies. This work studies the applicability of the proposed local perturbations paradigm to traditional regular topologies such as Torus, Hypercube and deBruijn graph and also designed regular logical topologies that treat reconfiguration as a new dimension to the topology design, while addressing other dimensions such as low diameter, less average internode distance and simple routing. The reconfigurable topologies are evaluated for uniform and non-uniform traffic conditions. Finally, LAN/MAN architectures using reconfigurable topologies are proposed.