|  |  | Summary

In this chapter, you learned that the function of the physical layer is to transmit data. In addition you learned that the following types of networking media may be used to connect computers:

- Coaxial cable consists of a hollow outer cylindrical conductor that surrounds a single inner wire conductor.
- UTP cable is a four-pair wire medium used in a variety of networks.
- STP cable combines the techniques of shielding, cancellation, and twisting of wires.
- Fiber-optic cable is a networking medium capable of conducting modulated light transmissions.

This chapter discussed various criteria, such as rate of data transfer and expense, that help determine which types of networking media should be used. You learned that TIA/EIA-568-A and TIA/EIA-569 are the most widely used standards for technical performance of networking media.

Additionally, this chapter described how bits propagating at the same time on the same network result in a collision. Lastly, you learned that a network may have one type of physical topology, and a completely different type of logical topology. In the next chapter, you will learn about LAN media and the IEEE model and how the data link layer provides reliable transit of data across a physical link by using Media Access Control (MAC) addresses.