Optical Burst Switching

Abstract

The concept of burst switching was proposed initially in the context of voice communications by Haselton (1983) and Amstutz (1983; 1989) in the early 1980s. More recently, in the late 1990s, optical burst switching (OBS) was proposed as a new switching paradigm for the so-called optical Internet in order to overcome the technical limitations of optical packet switching; namely, the lack of optical random access memory (optical RAM) and to the problems with synchronization.(Yoo & Qiao, 1997; Qiao & Yoo, 1999; Chen, Qiao & Yu, 2004; Turner, 1999; Baldine, Rouskas, Perros & Stevenson, 2002; Xu, Perros & Rouskas, 2001). OBS is a technical compromise between wavelength routing and optical packet switching, since it does not require optical buffering or packet-level processing as in optical packet switching, and it is more efficient than circuit switching if the traffic volume does not require a full wavelength channel. According to Dolzer, Gauger, Späth, and Bodamer (2001), OBS has the following characteristics: • Granularity: The transmission unit size (burst) of OBS is between the optical circuit switching and optical packet switching. • Separation Between Control and Data: Control information (header) and data are transmitted on different wavelengths (or channels) with some time interval. • Allocation of Resources: Resources are allocated using mainly one-way reservation schemes. A source node does not need to wait for the acknowledge message from destination node to start transmitting the burst. • Variable Burst Length: The burst size is variable. • No Optical Buffering: Burst switching does not require optical buffering at the intermediate nodes (without any delay).