On the deflection routing in QoS supported optical burst-switched networks

deflection routing is enabled, optical buffers are necessary to solve the insufficient offset time problem. Another solution, which can alleviate buffering, is to lengthen offset time in the beginning. As previous work indicated, a burst with extra offset time has higher priority than that without extra offset time and quality-of-service (QoS) can be accomplished in this way. Therefore, we investigate the performance of deflection routing in prioritized JET-based optical burst-switched networks. A queuing model is proposed to approximate loss probability. We also evaluate the impact of deflection routing in arpanet-2 topology by simulation. 1. INTRODUCTION Because of the pervasive usage of the Internet Protocol (IP), it has been a crucial issue to provide a reasonable solution of Optical Internet (i.e., IP-over-WDM) which can efficiently and flexibly utilize the huge potential capacity to accommodate the exploding Internet-based applications. As a matter of fact, the core of this issue lies in the design of switching paradigm. In recent years, a novel approach, named optical burst switching (OBS), has been proposed [10-11]. The incentive of this new idea is to retain advantages of wavelength routing and optical packet switching while eliminating their shortcomings as possible. The first step is to change the basic block from a fixed-length packet to a burst that is a super packet with variable size. Unlike a packet, a burst is a pure payload. Each burst is associated with a control packet recording related control information of the burst, e.g., burst length and routing information. In this way, the control overhead is alleviated. A control packet goes through O/E/O conversion at each intermediate node for electronically processing while a burst is completely in optical domain along the path without buffering. Compared with wavelength routing, the burst starts transmission without waiting for an acknowledgement from destination and the problem of significant signaling delay can be eliminated [10][13]. In addition, the separation between a control packet and its burst in both time and wavelength domain can avoid buffering as well as synchronization problem in optical packet switching [10]. According to signaling schemes, there can be various OBS protocols, e.g., Just-In-Time (JIT) by opened-ended reservation and Just-Enough-Time (JET) by closed-ended reservation [10][12][15]. In both protocols, a burst is transmitted after its control packet without waiting for an acknowledgement. In JIT, there are two types of control packets corresponding to a burst: setup packet and release packet. At each intermediate node, the desired …