Section 3.5. Summary

3.5. Summary

This chapter introduced the hardware building blocks of computer networks. These building blocks, or nodes, are directly connected by physical links and allow message exchange in communication networks.

A multiplexer is a device that provides cost-effective connectivity by collecting data from multiple links and carrying that data on one link. Multiplexers are of various types and are subject to some useful analytical methods . Networking modems are used to access the Internet from remote and residential areas. A DSL modem uses twisted-pair telephone lines to access the Internet, whereas a cable modem uses optical fiber cables to provide Internet access.

Switching devices are organized according to the layer at which they are connected in networks. Repeaters are layer 1 switching devices that primarily extend the geographic distance spanned by a LAN protocol. A hub or a bridge supports more ports than a repeater does. The most important component of the Internet, a router , is treated as a layer 3 switching device. A router is made up of input port processors , output port processors , switch fabric , and a switch controller .

In the next chapter, we look at issues related to data links. Data links can be evaluated both at the physical layer and the data link layer.