Differentiated Services Support In Optical Burst Switching Networks

The explosive growth of Internet is driving the demand for a high-speed transmission technology. DWDM (dense wavelength division multiplexing) technology has exploited the huge potential bandwidth of optical fibers to meet the bandwidth requirement. In order to efficiently utilize the raw bandwidth, IP packets should be transmitted and switched directly at the optical layer. Optical burst switching (OBS) has been proposed as a new optical switching technology combining the advantages of optical wavelength routing and optical packets switching. OBS is considered as a promising solution for optical Internet backbone in the near future. In OBS networks, several IP packets with the same egress router address and some common attributes like quality of service (QoS) are assembled into a burst which is to be forwarded through the network as one entity. An intrinsic feature of the OBS is the physical separation of transmission and switching of burst payloads and their headers, which helps to facilitate the electronic processing of headers at optical core routers and provide end-to-end transparent optical paths for transporting burst payloads.Differentiated Services (DiffServ) support in OBS networks is a very important issue. DiffServ models consist of relative DiffServ model and absolute Diffserv model. There are two main approaches to support DiffServ in OBS networks: using extra offset times and using special data channel scheduling.This dissertation focuses on DiffServ support in OBS networks and its content includes: the background of optical switching networks, the introduction of OBS networks, extra offset time based DiffServ mechanism and data channel scheduling based DiffServ mechanism. The research topics and our contributions are as follows.The architecture of OBS networks and some important issues including data channel scheduling algorithms and resource reservation schemes are introduced in Chapter 2. A new data channel scheduling algorithm called minimal wavelength converting times (MWCT) is proposed in this chapter to reduce the times of wavelength converting and consequently reduce the burden of core routers and negative influence on optical signal of the wavelength converting operation.Since the existing resource reservation scheme for OBS networks called just-enough-time (JET) can result in delay time redundancy and is not compatible with Deflecting Routing (DR) easily, a new resource reservation scheme called just-little-time (JLT) is put forwarded in Chapter 4. JLT scheme need only a small initial offset time and use optical buffers in core routers to compensate the offset time. JLT can reduce the end-to-end delay time of bursts and cooperate with DR without any modification. To support relative DiffServ in JLT-based OBS networks, PJLT (prioritized JLT) scheme is proposed in this chapter. The extra offset time is used in PJLT...