Optical switching
The appearance of enhanced multimedia services requiring huge bandwidths, such as broadcast high-definition television (HDTV) and video-on-demand, created a need for transitioning from basic interconnected rings to extremely high-capacity rings adjoined to mesh networks that can support clusters of up to 50 nodes in a metropolitan area. Therefore another network element with more sophisticated switching capabilities than a ROADM is needed This element, which is called an optical crossconnect(OXC), provides switched pass-through paths for express traffic that does not terminate at the node and an interface for dropping and adding optical signals at the node. The express traffic can be switched from any input to any output fiber. Internally such a device can have either an electrical or optical switching fabric. To understand basic optical switching technology, Sec.13.6.1 looks at general OXC configurations Sec.13.6.2 considers the performance impact when wavelength conversion is used, and Sec. 13.6.3 describes the standard implementations of wavelength routing or optical circuit switching.
As network traffic volume rises, particularly from the desire to have high-bandwidth multimedia services, the number of wavelengths per fiber will increase. This means that changes are needed for the earlier switching methods in which optical signals are converted to electrical signals, switched electronically, and then converted back to an optical format. The main reson is that the performance of the electronic equipment used in this optical-to-electrical-to-optical (O/E/O) conversion process is strongly dependent on the data rate and protocol. To overcone these limitations, the concept of all-optical switching was explored. Two approaches to this concept are optical burst switching (OBS) and optical packet switching(OPS). Sections 13.6.4 and 13.6.5, respectively, discuss these concepts.
Optical switching
The appearance of enhanced multimedia services requiring huge bandwidths, such as broadcast high-definition television (HDTV) and video-on-demand, created a need for transitioning from basic interconnected rings to extremely high-capacity rings adjoined to mesh networks that can support clusters of up to 50 nodes in a metropolitan area. Therefore another network element with more sophisticated switching capabilities than a ROADM is needed This element, which is called an optical crossconnect(OXC), provides switched pass-through paths for express traffic that does not terminate at the node and an interface for dropping and adding optical signals at the node. The express traffic can be switched from any input to any output fiber. Internally such a device can have either an electrical or optical switching fabric. To understand basic optical switching technology, Sec.13.6.1 looks at general OXC configurations Sec.13.6.2 considers the performance impact when wavelength conversion is used, and Sec. 13.6.3 describes the standard implementations of wavelength routing or optical circuit switching.
As network traffic volume rises, particularly from the desire to have high-bandwidth multimedia services, the number of wavelengths per fiber will increase. This means that changes are needed for the earlier switching methods in which optical signals are converted to electrical signals, switched electronically, and then converted back to an optical format. The main reson is that the performance of the electronic equipment used in this optical-to-electrical-to-optical (O/E/O) conversion process is strongly dependent on the data rate and protocol. To overcone these limitations, the concept of all-optical switching was explored. Two approaches to this concept are optical burst switching (OBS) and optical packet switching(OPS). Sections 13.6.4 and 13.6.5, respectively, discuss these concepts.
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