A comprehensive study on next-generation optical grooming switches

This paper investigates performance of different optical grooming switches, i.e., optical grooming crossconnects (OXCs), under a dynamic traffic environment. Four optical grooming OXC architectures are presented, namely, single-hop grooming OXC, multi-hop partial-grooming OXC, multi-hop full-grooming OXC and lighttree-based source-grooming OXC. After exploring these OXCs’ grooming capabilities, we proposed three grooming schemes and two corresponding algorithms, Grooming Using an Auxiliary Graph (GUAG) and Grooming Using Lighttree (GUL). Through these two algorithms, we evaluate the performance of different optical grooming OXCs in a dynamic traffic environment under different connection bandwidthgranularity distributions. Our experiment results illustrate that, (1) the multi-hop full-grooming OXC always has the best network performance, while it may encounter with cost and scalability constraints; (2) by using significantly less low-granularity electronic processing and through intelligent traffic-grooming algorithms, multi-hop partial grooming OXCs show reasonable good network performance; (3) the performance of a single-hop grooming OXC can be significantly improved by employing lighttree-based source-grooming scheme. From our results, we also observe that connection bandwidth-granularity distribution has a strong impact on network throughput and network resource efficiency, and hence should be carefully considered for network design and traffic provisioning. I. BACKGROUND INTRODUCTION A. Next-Generation Optical WDM Networks Fiber optics and wavelength-division multiplexing (WDM) technology have significantly increased the transmission capacity of today’s transport networks, and played an extremely important role to support the explosively increased Internet traffic as well as large amount of traditional traffic. Using WDM technology, the bandwidth of a fiber link can be divided into tens (or hundreds) of non-overlapped wavelength channels (i.e., frequency channels), each of which can operate at the peek electronic processing rate, i.e., over gigabits per second. The bandwidth of a wavelength channel can be further divided into finer granularity trunk using Time-division multiplexing (TDM) technique and be shared by different end users. An end user can be any type of client network equipments such as IP, ATM or Frame relay network equipment. Hence, optical WDM network have served as an important platform (a circuit core) to provide network connectivity as well as transmission capacity to today’s Internet infrastructure and application service. As WDM switching technology keep maturing, optical WDM networks is expected to evolve from interconnected SONET/WDM ring topologies to irregular mesh topologies, and network provision procedure will migrate from an on-site manually interconnecting process to a point-and-click or on-demand automatic