All of these impressive connections that start with Ts and Os are powerful, but they are not in and of themselves a complete WAN solution. These WAN connections with their unique packets (DS0, STS, and so on) make up the entire mesh of long-range connections called the Internet, carrying both packetized voice data and TCP/IP data packets. All of these connections are point-to-point, so you need to add another level of devices to enable you to connect multiple T1s, T3s, or OC connections together to make that mesh. That’s where packet switching comes into play.
The first generation of packet-switching technology was ...