Today’s telecommunication world is seeing dramatic changes in network infrastructures and services. These changes are mainly driven by the ever-growing rate of network traffic. Global Internet traffic is doubling each year due to both tremendous growth in the number of users and rapid increase of bandwidth accessible by each user (e.g., the Global Internet Geography report (2004) stated that in Asia, Internet traffic growth was about 400 percent in the year 2004). Not only is network traffic growing at an unprecedented speed, but the traffic mix is changing greatly. The traditional voice traffic volume has now become very small relative to the huge volume of data and video traffic, due to the deployment of Gigabit technologies in the access part of the service providers’ networks.
Key Terms in this Chapter
Optical Network: A high capacity telecommunication network operating based on optical technologies and components (e.g., optical transmission, optical fiber, lasers, optical amplifiers, etc.). Optical networks allow for the transmitting of user data at very high bit rates at single wavelength (e.g., 10 Gbits/s, 40 Gbits/s, etc.).
Optical Packet Switching Network: an optical network in which packets are switched optically without being converted to electrical signal.
Circuit Emulation Service: A technology allowing the transport of TDM service such as PDH (E1/T1/E3/T3) as well as SONET/SDH circuits over packet-switching networks.
Circuit Switching: A communication technology in which a dedicated circuit (channel) is established for the duration of a transmission. In circuit-switching networks, network resources are static and remain dedicated to the circuit during the entire transmission. This technology, combined with TDM technology, is mostly used in the well-known telephony and SONET/SDH networks for transporting voice traffic.
Packet Switching: A communication technology in which a message is broken into packets, each of which can take a different route to the destination where packets are recompiled into the original message. In packet-switching networks, network resources are not static, but are dynamically shared by several packet streams. Packet-switching technology was usually used for transporting enterprise data traffic, but nowadays it is gradually introduced into optical networks for transporting both voice and data traffic.
Time Division Multiplexing: A technology that increases transmission bit rate by multiplexing many lower rate data streams into a higher rate data stream. The multiplexer herein typically interleaves (in time domain) the lower rate streams to obtain the higher rate stream.
Metropolitan Area Network: A set of computer networks or telecommunication networks that work together to provide access and services in a metro region such as a large campus or a city (IEEE Standard 802, 1990).