Solving Large Instances of the RSA Problem in Flexgrid Elastic Optical Networks

Abstract

Abstract-We present an optimization procedure that mixes advanced large scale optimization methods and heuristics to solve large instances (with over 1.7 million integer variables) of the routing and spectrum allocation (RSA) problem -a basic optimization problem in flexgrid elastic optical networks. We formulate the problem as a mixed-integer program for which we develop a branch-and-price algorithm enhanced with such techniques as problem relaxations and cuts for improving lower bounds for the optimal objective value, and an RSA heuristic for improving the upper bounds. All these elements are combined into an effective optimization procedure. The results of numerical experiments run on network topologies of different dimensions and with large demand sets show that the algorithm performs well and can be applied to the problem instances that are difficult to solve using commercial solvers such as CPLEX.Index Terms-branch and price, cuts, elastic optical networks, large-scale optimization, mixed-integer programming, relaxations, routing and spectrum allocation.

A Topology-Based Spectrum Assignment Solution for Static Elastic Optical Networks With Ring Topologies

“…To face the spectrum fragmentation, there are some works focused on the routing strategy [17], [22], [25], [26], and some others focused on the spectrum assignment [10], [14], [18], [21], [23], [27]- [33]. Besides, some works in the literature consider that the order in which users are served on the spectrum assignment solutions is considered significant on static network operation circumstances because it can directly impact the fragmentation of the spectrum and its available use [1], [27]- [33].…”

Optimization of Optical Networks Based on CDC-ROADM Technology

“…Only a contentionless architecture, allows multiple copies of the same wavelength on a single add/drop Mux. Thus only a colorless, directionless architecture combined with contentionless functionality is the end goal of any network operator that has deployed or is planning to deploy ultimate level of flexibility in the optical layer [9] especially together with flexible wavelength assignment [4,10]. Further, the advantages of CDC-ROADMs enable operators to offer a flexible service and provide significant savings in Operational Expenditure (OpEx) and Capital Expenditure (CapEx).…”

“…During the last decade, the attention of the telecommunication community has been concentrated on Routing and Wavelength Assignment (RWA) and Routing and Spectrum Allocation (RSA) problems. Consequently, numerous exact and heuristic methods are now available to solve RWA and RSA problems in static [9][10][11] and dynamic [12][13][14] environment. However, so far the relevance of the inner optical node architecture in the DWDM network optimization has not been fully considered.…”

A column generation technique for routing and spectrum allocation in cloud–ready survivable elastic optical networks

“…Hence, some large-scale optimization approaches are necessary. Here, the column generation (CG) technique seems to be a promising approach, since it has been successfully applied to different optimization problems (Klinkowski et al, 2016;Ruiz et al, 2013;Żotkiewicz et al, 2015).…”

“…Klinkowski et al (2016), Ruiz et al (2013) or Velasco et al (2014) focus on efficient methods to solve the problem of allocating unicast demands in an unprotected EON. It is worth mentioning that Ruiz et al (2013) and Velasco et al (2014) apply the CG technique directly to solve RSA while Klinkowski et al (2016) propose a branch-and-price approach that incorporates, among others, CG. Next, focus on optimization of anycast traffic in an unprotected EON wherein they model an anycast demand as a one-directional transmission from a DC to the client node.…”