A novel MAC protocol for improving performance in CORNet

The collision-free optic-burst network (CORNet) was proposed in order to avoid the channel collision in OBS ring network. The CORNet employs the multi-token access control algorithm (MACA) to solve the channel collision problem. The MACA protocol uses multiple tokens to manage the accessibility of all data wavelengths and the tokens are synchronously transmitted around the ring. However, the MACA in CORNet has some limitation to use network resources because tokens are synchronously transmitted around the ring and nodes should wait for available bandwidth between two adjacent tokens before transmitting bursts. Thus, the resources are wasted although the MACA can guarantees a collision-free by the synchronous management of tokens. In this paper, we focus on improving the performance of the collision-free optic-burst ring network. We propose a new protocol which reuses the wavelengths to increase the utilization of resource in the CORNet named protocol for reusing available drop-wavelength appropriately (PRADA). The proposed protocol can be implemented based on three queue selection methods to reuse available wavelengths after dropping sub-bursts at destination: best-fit (BF), farthest sub-burst (FB), and neighbor sub-burst (NB). The performance of the proposed protocols with three queue selection methods is evaluated and compared in terms of throughput and average queuing delay through OPNET simulation. The simulation results show that three proposed schemes increase the throughput about 10% and lower queueing delay than DT-WSC. And the BF achieves the best performance among the three queue selection schemes.