Inter-Exchange Carrier (IXC) networks are used to link telephone networks within geographical service area to each other. AT&T, Sprint, MCI, and Qwest are examples of well-known IXCs.
In order to provide the bandwidth necessary to carry the volume of long-distance voice and data traffic at reasonable cost, most IXCs have deployed large bundles of fiber-optic cables that interconnect their switching systems. Burying thousands of miles of fiber cable is costly. However, each pair of fibers is capable of providing many Gbps of bandwidth.
The explosion of the Internet and the demand for advanced multi-media services continues to drive the demand for increased bandwidth at low cost. To increase the capacity of fiber cables, new fiber optic technology has emerged. By utilizing a technology known as dense wavelength division multiplexing, DWDM, each fiber can carry 80 or more separate light-waves. As of 2001, some DWDM technologies were capable of providing over 1 Tbps (1,000 Gbps) of bandwidth, enough to transmit in one second the contents of 150,000 encyclopedias. Advances in optical networking equipment and light-wave amplification technologies will continue to add bandwidth the fiber networks.
Picture on top shows the typical inter-exchange carriers (IXCs) connections. This diagram shows that there are many different IXCs. Each of these IXCs must interconnect to the local telephone companies at a defined point of presence(POP)...
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