On the analysis of burst-assembly delay in OBS networks and applications in delay-based service differentiation

In Optical Burst Switching (OBS), packets travel through the network core as part of longer-size optical bursts, which do not suffer electronic conversion until they reach an eggress point. Typically, such optical bursts comprise tens or hundreds of packets, which are assembled/deassembled at border nodes. During the burst-formation process, each arriving packet must wait until the final burst is complete, which clearly adds an extra delay on each packet in the burst, especially on those arriving earlier. However, such burst-assembly delay may be excessive for the appropriate performance of certain applications, mainly real-time interactive ones. This work’s findings are twofold: first, it characterises the burst-assembly delay distribution of each packet in a burst arisen by the main assembly algorithms found in the literature; and, second, it introduces a new burst-assembly strategy that takes into account the particular delay constrains of packets in the formation of optical bursts, along with a detailed study of its properties. This work has been funded by the “Ministerio de Educación y Ciencia” of Spain under grant TEC2006-03246.