Optical Burst Switching
Joel J.P.C. Rodrigues (Instituto de Telecomunicações, University of Beira Interior, Portugal), Paulo P. Monteiro (Universidade de Beira Interior, Portugal) and Pascal Lorenz (SIEMENS S.A. and Universidade de Aveiro, Portugal)
Copyright: © 2005
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).