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2.2 | |
Bandwidth | |
| 2.2.4 | |
Limitations |
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Bandwidth varies depending upon the type
of media as well as the LAN and WAN technologies used. The physics of the
media account for some of the difference. Signals travel through
twisted-pair copper wire, coaxial cable, optical fiber, and air. The
physical differences in the ways signals travel result in fundamental
limitations on the information-carrying capacity of a given medium.
However, the actual bandwidth of a network is determined by a
combination of the physical media and the technologies chosen for
signaling and detecting network signals.
For example, current understanding of the physics of unshielded twisted-pair (UTP) copper cable puts the theoretical bandwidth limit at over one gigabit per second (Gbps). However, in actual practice, the bandwidth is determined by the use of 10BASE-T, 100BASE-TX, or 1000BASE-TX Ethernet. In other words, the actual bandwidth is determined by the signaling methods, network interface cards (NICs), and other items of network equipment that are chosen. Therefore, the bandwidth is not determined solely by the limitations of the medium. Figure
Figure
|
shows some
common networking media types along with the limits on distance and
bandwidth when using the indicated networking technology. 
summarizes
common WAN services and the bandwidth associated with each service.
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