WANs connect networks, users, and services across a broad geographic area. Companies use the WAN to connect company sites for information exchange (see Figure 9-1).
Figure 9-1. WAN Connections
WAN serial interfaces, defined as follows, are either synchronous or asynchronous:
Synchronous links have identical frequencies and contain individual characters encapsulated in control bits, called start/stop bits, which designate the beginning and end of each character. Synchronous links try to use the same speed as the other end of a serial link. Synchronous transmission ...