On the benefits of selectively delaying bursts at the ingress edge nodes of an OBS network

Optical burst switching (OBS) networks rely on complex and costly contention resolution strategies to reach reasonable bandwidth utilization efficiency. Recent research efforts have suggested that proactive contention minimization strategies based on selectively delaying bursts at the ingress edge nodes, exploiting their inexpensive electronic buffers, can assist in the task of relaxing the hardware requirements of the network core nodes. This paper considers the main strategies of selectively delaying bursts at the ingress nodes, establishing their similarities and differences. The performance of these strategies is evaluated and compared by means of network simulation. The results show that a contention minimization strategy using the selective ingress delays to increase the degree of isolation on different wavelengths of burst traffic going through overlapping paths achieves the largest reduction of burst losses. Moreover, this performance improvement can be attained while at the same time reducing the number of wavelength converters required at the core nodes and slightly relaxing the number of transmitters and receivers needed at the edge nodes, provided that tuneable devices are employed.