Quality-of-Service in Optical Burst Switched (OBS) Networks

Abstract

In today’s world everyone knows about the importance of internet. As the usage of internet increases with passage of time. The users from around the world need high bandwidth to use internet for the transmission of their data. The applications like video streaming, online games, multimedia applications etc requires high bandwidth. To fulfill the demand of high bandwidth users optical burst switched was introduced. In optical burst switched networks the data can be transmit at a speed of tera bit per second. To achieve this high speed in OBS, wavelength division multiplexing is used in many backbone networks. OBS has the ability to transfer bursty traffic. Normally in IP networks best effort service is used to provide quality-of-service for the transmission of data. To attain smooth transmission of bursty traffic in optical burst switched networks some quality-ofservice mechanisms are used. For example, offset based mechanism, burst assembly based mechanism, burst preemption based mechanism, and active dropping based mechanism. Our contribution in OBS is to provide quality-of-service. For this purpose we combine the advantages of the existing quality-of-service mechanisms. We use the basic concept of Composite burst assembly with high priority at the middle. In traditional composite bust assembly the high-priority are placed at head of the burst and low-priority packets at the tail of the burst. Then composite burst assembly with high-priority packets at middle has good results. We generalize the composite burst assembly with high-priority packets at the middle by proposing four techniques to provide QOS in OBS. The first technique known as Composite burst assembly with high-priority at the middle with maximum distance between priorities. When there are various priorities, then the highest priority will be placed at the middle of the first burst and the lowest priority packet will be placed at the tail and head of the burst. In this way the second and third and so on bursts will be made. The priority of the first burst will be greater than second, and that the priority of second burst will be greater from third and so on. The second technique is called as composite burst assemble with high-priority at the middle with equal distance between priorities. In this method the priorities is divided in two parts. In first burst the priority the first priority from the first part will be placed at the middle, and the first low-priority from the second part will be placed at the head and tail. The third technique is same as the first one, but if some priorities are missing, then it follows the concept of first technique and dynamically selects the available highest priority and available lowest priority and assemble burst from them. The fourth technique follows the second technique. If priorities are missing, then this method is using the basic theme of the second technique and dynamically selects the packets according to their priority.