On Minimizing Band Size in Limited Reconfigurable Optical Networks

Abstract

In this paper, we consider a uni-directional ring network with limited reconfigurability and take up the problem of supporting all-to-all traffic -while minimizing the worstcase wavelength range of the reconfigurable optical add drop multiplexers (ROADMs). ROADMs can be limited in range (LROADMs) or have full range (F-ROADMs). The cost of such a network is dominated by the number of wavelengths to be added or dropped by ROADMs. Limiting the range of wavelengths that can be accessed at a node reduces costs. Here, we develop an integer linear programming (ILP) formulation for this problem, and also propose a new wavelength assignment heuristic where we evalute it using the ILP formulation. We conclude that the performance of our proposed heuristic is very close to optimal and the worst-case range is only about 65% of the full range for moderately large number of network nodes.

Wavebanding in Bi-Directional WDM Ring Networks with Limited Reconfigurability

“…Unlike [3], we consider a bi-directional ring topology and assume that the bands of different L-ROADMs may be different. We presented some results for wavebanding in uni-directional ring networks in [7] and [8]. In [9], we considered a bi-directional ring network and presented some results for all-to-all traffic.…”

“…In this work, L-ROADMs are limited-add whereas in [9], the L-ROADMs were limited add/drop. This paper and [7][8] [9] have the same main goal, to minimize the band size of the LROADMs and maximize the number of L-ROADMs. Here, we derive an upper bound for the number of F-ROADMs needed for permutation traffic, when the L-ROADMs have a given band size.…”

“…Since LROADMs have smaller tunable ranges than F-ROADMs, they are less expensive than F-ROADMs. This paper and [7][8] [9] are motivated by [3] which first considered the problem of determining the band size and the number of L-ROADMs that can satisfy a given traffic demand. Specifically, the paper considered all-to-all (one lightpath between every pair of nodes) traffic in a ring network and answered the question: what is the maximum number of LROADMs of band-size K that can be used to set up all-to-all traffic?…”