A joint congestion control and burst contention control design for optical burst switching networks

Abstract

Optical burst switching (OBS) networks have suffered from the burst contention problem due to its limited functioned optical buffer. Burst contentions take place i) when the network is congested by increased input traffic, or ii) two or more bursts demand the same wavelength exactly at the same time even though there is no congestion. From these insights, we present three methods that make higher throughputs and lower burst losses in the OBS network.

First, from the viewpoint of flow control, we propose a burst flow control algorithm that controls the length of a burst based on the congestion price on its path. With the proposed flow control algorithm, the OBS network achieves improved efficiency given QoS constraint such as burst loss ratio compared to the case where a burst contention resolution scheme is solely used.

Next, to remove expensive optical buffer inside OBS network, we develop an edge delay method which decreases burst losses especially by resolving overlapped bursts only in a specified node. When some bursts go through the contention and need buffering to avoid contentions in the node, instead of using optical buffer, the proposed method makes them be delayed initially for the required buffering time at its ingress edge node.

Lastly, we propose the joint control framework which control both OBS network congestion and the burst contention. Proposed joint optimization of congestion control and burst contention control can significantly increase OBS network capacity, nearly achieving no burst loss at any utilization. We firstly design a distributed optimal resource allocation framework in OBS network using the utility maximization problem. In addition, varying the utility function of this optimization scheme, we can apply various resource sharing policy in OBS network as we do in the existing queue based networks.