Dynamic Deflection Routing with Virtual Wavelength Assignment in Optical Burst-Switched Networks   SuKyoung Lee* Sejong University, Seoul, Korea LaeYoung Kim, JooSeok Song Yonsei University, Seoul, Korea David Griffith, Kotikalapudi Sriram National Institute of Standards and Technology, Gaithersburg, MD, USA Received February 23, 2004; Revised 3 August 2004; Accepted August 4, 2004 Abstract. In optical burst-switched networks, one of the most significant issues is contention resolution. There have been several deflection routing techniques as contention resolution. While contention is resolved by traditional deflection routing, it cannot guarantee that the control packet will reserve all the wavelengths successfully to the destination on the alternate path, especially when traffic load in a network is high. Therefore, in this paper, we propose a Deflection Routing with Virtual Wavelength Assignment (DR-VWA) algorithm in order to provide a higher resource guarantee for loss-sensitive traffic bursts. The proposed DR-VWA scheme (1) dynamically decides the alternate path with the least traffic load and (2) allows high-priority bursts in terms of loss to be assigned available wavelengths over the path virtually. The proposed scheme is evaluated through simulation, and it is shown that significant improvement with regard to burst loss and wavelength conversion cost can be achieved. Keywords: optical burst switching, deflection routing, virtual wavelength assignment, burst blocking 1 Introduction Optical Burst Switching (OBS) has been proposed as a suitable switching paradigm to exploit the terabit bandwidth in Optical Internet. It tries to combine the best of both circuit and packet switching while avoiding their shortcomings. In optical burst-switched networks, a control packet is sent first on a separate control channel ahead of a variable-length data burst in order to reserve bandwidth resources prior to the arrival of each data burst on a data channel. That is, an instan- taneous circuit is established and the resources are occupied just until the burst has passed. In an OBS network, contention resolution is necessary in order to handle the case where mul- tiple bursts are destined to go out on the same output port at the same time. Because this is a severe problem that frequently arises in an OBS network, several contention resolution techniques have been proposed such as optical buffering using Fiber Delay Lines (FDLs), wavelength conversion, and deflection routing. Due to the immaturity in both optical buffering and wavelength conversion techniques, deflection routing has received a lot of attention most recently [1–5]. The deflection routing function implemented in each switch automates the setups of alternate paths when a control packet encounters a congested node over the primary path. Generally, deflection routing re-routes data on different links, resulting in much less resource contentions. Thus, due to the fact that *Corresponding author.   This work was supported in part by the Korea Science and Engineering Foundation (KOSEF) through OIRC project and by the US National Communications System (NCS). Photonic Network Communications, 9:3, 347–355, 2005 Ó 2005 Springer ScienceþBusiness Media, Inc. Manufactured in The Netherlands.