3.5. SummaryThis 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. |