A light-trail is a generalization of a lightpath allowing multiple nodes to be able to communicate along the path, leading to all-optical spatial traffic grooming. A light-trail exhibits properties of dynamic bandwidth provisioning, optical multicasting and sub-wavelength grooming, and architecturally is analogous to a shared wavelength optical bus. Arbitration within the bus is conducted by an out-of-band control channel. The bus feature results in a node that has a large pass-through loss, restricting the size of a light-trail to metro environments. Due to this limitation, it is difficult to extend the light-trail concept to regional or core networks. In this paper we exhaustively investigate the concept of multi-hop light-trails (MLTs)—a method to provide multi-hop communication in light-trails, thus enhancing their reach. Node architecture and protocol requirements for creating MLTs are discussed. We then discuss design issues for MLTs in regional area networks through a problem formulation that is solved using convex optimization. The problem formulation takes into consideration issues such as routing MLTs as well as assigning connections (defined as sub-wavelength traffic requests) to MLTs. Two polynomial-time heuristic algorithms for creation of MLTs are presented. One of the algorithms is a static implementation, while the other is a dynamic implementation—with unknown traffic. A detailed delay analysis is also presented that enables computation of end-to-end delay over MLTs using different flow assignment algorithms. A simulation study validates the MLT concept.
© 2012 OSA
Original Manuscript: January 10, 2012
Revised Manuscript: July 27, 2012
Manuscript Accepted: September 6, 2012
Published: November 30, 2012
Ashwin Gumaste, Tamal Das, Raviraj Vaishampayan, Jianping Wang, and Arun Somani, "Extending Light-Trails to Regional Networks: Multi-hop Light-Trails (MLT)—System Design and Performance," J. Opt. Commun. Netw. 4, 1046-1061 (2012)