Extending light-trail into elastic optical networks for dynamic traffic grooming

A light-trail in a traditional ITU−TITU−T fixed wavelength grid optical network is a generalization of a lightpath. Multiple nodes in a light-trail are allowed to communicate each other along the light-trail, leading to sub-wavelength granularity utilized traffic grooming. Architecturally, a light-trail is analogous to a shared wavelength optical bus. Moreover, a new light-trail is always equipped by a guard band for non-interference of optical signals. Therefore, multiple light-trails must be accompanied by multiple guard bands, which indeed is an absolute wastage of optical spectrum resources. In the recent years, besides RWA (Routing and Wavelength Assignment) in WDM (Wavelength Division Multiplexing) optical networks, the Routing and Spectrum Assignment (RSA) algorithm is widely being adopted in many new and emerging elastic optical mesh networks to perform traffic grooming. In such networks, Orthogonal Frequency Division Multiplexing (OFDM) technology is a promising candidate to execute a RSA algorithm and implement an elastic lightpath as a result. The algorithm is capable of transmitting high-speed data stream using multiple low-speed spectrum overlapped sub-carriers (mini-grids). Hereafter, in this paper we have introduced a novel concept (based on our knowledge and belief) elastic light-trail (a variant of an elastic lightpath) in elastic optical networks and proposed an algorithm “Multi-hop Elastic Light-Trail – MELT” that performs an elastic light-trail expansion and/or contraction (in frequency domain), instead of creating a new elastic light-trail where applicable. Otherwise, the algorithm creates a new elastic light-trail that facilitates required data transportation. In this work, we investigate optical spectrum utilization efficiency for proposed elastic light-trail, existing elastic lightpath (Multi-hop Elastic Lightpath algorithm – MEL  ) and ITU−TITU−T wavelength grid fixed lightpath (Multi-hop Lightpath algorithm – ML) and perform comparison measurements.