Routing, Spectrum, and Transponder Assignment in Elastic Optical Networks

Abstract

Abstract-Backbone networks are evolving toward Elastic Optical Network (EON) architecture that allows a flexible and efficient use of spectrum resources. Flexibility in EONs is guaranteed also by emerging sliceable bandwidth variable transponders (SBVTs) that support the simultaneous generation of multiple optical carriers. Such carriers can be used to serve different lightpaths (i.e., slice-ability), or can be merged into a single high-rate super-channel.SBVTs typically use a dedicated laser to generate each carrier, i.e., multi-lasers SBVT (ML-SBVT). Alternatively, a multi-wavelength source can be used to generate multiple carriers using a single laser, i.e., multi-wavelength SBVT (MW-SBVT). Using MW-SBVT improves the super-channel spectrum efficiency. Indeed, MW-SBVT reduces the intercarrier interference among the sub-carriers composing the super-channel, thus it is possible to reduce the guard bands among sub-carriers. With ML-SBVT, each sub-carrier suffers from unstableness of the related laser and inter-carrier interference may have a huge impact, thus higher guard bands are needed. On the other hand, the use of a MW-SBVT introduces specific constraints to the routing and spectrum assignment (RSA) because the spacing among the sub-carriers is limited to a range of specific values.To take into account the constraints introduced by transponders, this paper integrates the selection of the transponder into RSA thus proposing a dynamic routing, spectrum, and transponder assignment (RSTA) scheme supporting both ML-SBVT and MW-SBVT technologies, and aiming to combine the benefits of the two technologies. Simulation results show that the proposed RSTA scheme provides benefits in terms of achieved blocking probability compared to traditional RSA schemes. Moreover, the achieved results demonstrate that by jointly using both SBVT technologies provides significant benefits with respect to the utilization of any single SBVT technology.

A Survey of Optical Carrier Generation Techniques for Terabit Capacity Elastic Optical Networks

“…Improved routing, spectrum and transponder assignment techniques have been recently proposed to improve the network performance in presence of MW sources [77].…”

“…In addition, a novel routing, spectrum and transponder assignment (RSTA) algorithm was proposed. It combined the transponder selection with RSA by taking into account the knowledge of transponder technology, current availability, and the constraints introduced by each specific transponder [77], [271]. The study evaluated the network performance for two different transponder technologies (ML-SBVT and MW SBVT), considering two traffic profiles (400 Gb/s traffic only and hybrid traffic) and three node architectures (100%MW, 100%M L, x%MW and y%M L), where x and y represent respectively the percentage of the MW and ML transmitters within the node.…”

“…The performance of RSA and RSTA was also compared in a heterogeneous node architecture, where the node was equipped with both type of transponders in different percentages (x%MW and y%M L), to combine their respective benefits. The RSTA scheme provided significant network performance enhancement, compared to conventional RSA schemes, by efficient assignment of a transponder to a specific light-path request, depending on the transponder technology and the light-path spectrum requirements [77], [271].…”

“…The idea of having two types of transponder technologies, combining the benefits of ML-SBVT and MW-SBVT [77] for enhanced network performance is interesting, but not without drawbacks. First, it is in contrast to the concept of having a bandwidth variable transponder supporting multiple rates and reach.…”

Bin-packing based optimisation of EON Networks with S-BVTs

“…The key novel element of EON are elastic optical paths (EOP) accessible by the client signals through devices called bandwidth variable transceivers (BVT) [3], [4], [5]. Establishing EOPs provides for very efficient use of the fibre's frequency spectrum when carrying synchronous client signals with diverse bitrates.…”