GMPLS/PCE-controlled multi-flow optical transponders in elastic optical networks [Invited]

Elastic optical networks aim at considerably improving network spectrum efficiency by using a flexible grid, while traditional optical transport networks operate with fixed frequency spacing. In such flexible networks, connections are accommodated into so-called “frequency slots,” which are dynamically established depending on client data rates and selected signal modulation formats. Key enablers to develop such a network infrastructure are bandwidth variable optical cross-connects (BV-OXCs) and BV transponders. For the latter, a multi-flow optical transponder (MF-OTP) is being considered as an appealing solution because of its support of high-rate super-channels as well as its elasticity, where optical connections can be reconfigured flexibly according to the required traffic requests. The dynamic selection (path computation) and automatic network configuration of both optical spectrum and MF-OTP resources are handled by a control plane entity. Herein, a distributed Generalized Multi-Protocol Label Switching (GMPLS) control plane combined with an active Path Computation Element (PCE) are adopted for the dynamic instantiation of flexgrid optical connections. To fully control the MF-OTP's attributes and capabilities, specific extensions are required for both GMPLS routing and signaling.We propose and experimentally validate such extensions by considering two information models: partial and full. The difference between the models lies in information related to optical spectrum status (carried by the full model) on the MF-OTP interfaces attached to the BV-OXCs. Furthermore, a novel online routing, spectrum, and modulation assignment (RSMA) algorithm is conceived. The RSMA adopts both models to compute paths by trying to optimize the spectral link and MF-OTP resources when dynamically serving flexgrid connections. The experimental evaluation compares the models' attained RSMA performance with respect to the blocking probability as well as the setup and path computation delays.