The Obs Reservation Protocol And Channel Scheduling Algorithm Research

Today the fast-growing Internet traffic is demanding increased network capacity, as well as support for differentiated services. Wavelength-division multiplexing (WDM) technology has provided an opportunity to drastically increase network capacity. Optical burst switching (OBS) has proposed by Chunming Qiao and J. S.Turner in 1998. It combines the advantages of optical circuit switching (OCS) and optical packet switching (OPS). OBS adopts one-way reservation protocol and takes the burst packet as the minimum switching unit. Before the burst packet is sent, the control packet has already reserved the optical path. So the burst packet can be transmitted transparently without O/E or E/O conversion. At the same time control packet is processed in electronic domain. This will avoid the use of FDL and reduce the requirements for optical devices. Therefore OBS has become the ideal optical switching scheme.In this thesis we studied the principles of OBS, its network architectures and module functions, as well as a detailed analysis of the key technologies in OBS such as burst control packet (BCP) management scheme, scheduling scheme of data channel, resource reservation mechanism, solution for data channel competition. Based on the existing research works, we proposed a new solution for resource competition and channel allocation scheme in OBS network core nodes.Following are our main contributions in this thesis:The contention resolution methods including optical buffering, the wavelength converter, the deflection routing, the burst segmentation and resource reservation scheme for OBS networks were introduced in Chapter 3. Then a new scheme for reducing burst contention based on JET protocol in OBS is proposed. When competition occurs, those bursts with low priorities and small sizes is delayed after the duration of competition.The burst fabrication mechanisms and the data-channel scheduling algorithms were discussed in Chapter 4. Based on LAUC-VF channel allocation scheme in OBS networks, we proposed a new diff-serv capable method for channel allocation, which can not only guarantee low delay time for high priority services, but also make them share bandwidth with low priority services.