Two methods of optical switching widely used are optical circuit switching (OCS) and optical packet switching (OPS). In OCS, switching operation is carried out at the granularity of an optical circuit. In OPS, switching operation is carried out at the granularity of packets. OPS require packet header recognition unit, header processing unit and a control unit. Here operation is on packet by packet basis. Latest development resulted in the introduction of optical burst switching (OBS) which include some features of OCS and OPS. Here packets are assembled into larger data bursts. For this, a burst header packet (BHP) is created. BHP contains all the information to configure downstream optical switching fabrics for the incoming data burst. Different optical technologies exist in market are electro optic switching, acousto-optic switching, thermo-optic switching, opto-mechanical switching and optical amplifier based switching.
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