OPN05-6: Performance Enhancement in OBS Network with Flow Control and Edge Delay Method

Abstract

This paper examines burst contention resolution problems in optical burst switching (OBS) networks. Since 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 two novel 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 and fairness compared to the case where a burst contention resolution scheme is solely used.Next, we develop an edge delay method which decreases burst losses especially when two or more bursts are overlapped in the core nodes. When some bursts need buffering to avoid contentions at core nodes, the proposed method makes them be delayed for the required buffering time at its ingress edge instead. Through extensive simulations, we demonstrate its performance.

Joint Congestion Control and Burst Contention Resolution in Optical Burst Switching Networks

“…So, the contentions are the problem of not only congestion, but also the time overlap of consecutive bursts at an optical link. For that reason, the proactive congestion control schemes [4], [7] can achieve low burst losses only when sacrificing their network utilization. If they increase target utilization threshold, the burst loss ratio is also increased.…”

“…An alternative approach to reduce the network contention is to proactively prevent an OBS network from entering the congestion state that invokes lots of burst contentions. Several recent schemes [4], [7] including our earlier work are designed to follow the congestion control approach [8]- [12], which is limiting the individual burst length based on the network utilization status.…”

“…Optical Burst Switching (OBS) [1]- [7] has been proposed as a future high-speed switching technology that combines the advantages of optical circuit switching and optical packet switching. In OBS network, multiple IP packets with the same destination are assembled into a burst at an ingress OBS node and the burst is transmitted through the network core entirely in the optical domain.…”

A Joint Design of Congestion Control and Burst Contention Resolution for Optical Burst Switching Networks

“…An alternative approach in this regard is to proactively prevent an OBS network from entering the congestion state which may incur lots of burst contentions. Some recent schemes [4], [9] including our earlier work are in this line of work adopting congestion control approach [10]- [14] in electrical packet switching networks. Especially, our previous work [9] investigated the impact of flow control and burst delay control on the performance of OBS network.…”

“…Some recent schemes [4], [9] including our earlier work are in this line of work adopting congestion control approach [10]- [14] in electrical packet switching networks. Especially, our previous work [9] investigated the impact of flow control and burst delay control on the performance of OBS network. However, those two controls work independently of each other, and hence, it was not clearly understood how they have to interact with each other in order to improve the performance of OBS network.…”