Transmission Media

Transmission Media

On any network, the various entities must communicate through some form of media. Just as humans can communicate through telephone wires or sound waves in the air, computers can communicate through cables, light, and radio waves. Transmission media enable computers to send and receive messages but do not guarantee that the messages will be understood.

This chapter discusses some of the most common network transmission media, such as coaxial cable, shielded twisted-pair cable, and unshielded twisted-pair cable. You also learn about network fiber-optic cable and wireless communications. To lay the groundwork for these issues, the chapter begins with an introduction to radio frequency transmissions and a look at some important characteristics of transmission media.

This chapter targets one multipart objective in the Planning section of the Networking Essentials exam:

Select the appropriate media for various situations. Media choices include the following:
Twisted-pair cable
Coaxial cable
Fiber-optic cable
Wireless communications
Situational elements include the following:
Cost
Distance limitations
Number of nodes

Transmission Media Types

The most common type of media is copper cable. The most common types of copper cabling are twisted-pair and coaxial. Twisted-pair cabling used in a LAN is similar to the cabling used to connect your telephone to the wall outlet. Network coaxial cabling, on the other hand, is similar to the cable used to connect your television set to the cable TV outlet.

Another type of LAN connection media quickly gaining popularity is fiber-optic cable. Consisting of a number of glass or high-grade plastic optical strands surrounded by a tough cloth-and-plastic wrap, fiber-optic cables resemble coaxial cables from the outside. Fiber-optic network cabling is similar to the fiber-optic strand used in the fiber-optic lamps found in novelty stores, in which colored lights feed into optical strands to create the appearance of dozens of pinpoints of light.

Wireless media, which is, in a sense, no media at all, is also gaining popularity. Wireless transmissions use radio waves or infrared light to transmit data. Many major network vendors now offer wireless network adapters.

Further Information