ket-Switched Networks destination point with high integrity. The connectionless environment offered the flexibility of routing around problem areas, but at the risk of greater overhead asso- ciated with the overall transmission because addressing had to be included in each packet, and also at the risk of greater delays because each packet had to be inde- pendently routed. In 1970 Tymnet introduced X.25, which was the first generation of packet switch- ing. X.25 packet-switching networks evolved as an option for data communica- tions and therefore did not compete directly with the telephony providers. The providers of such networks were put in a special category, called value-added net- work (VAN) providers. The X.25 packet-switching technique emerged out of a need to address the bursty data flow associated with interactive processing which emerged in the late 1960s. Because bursty data implies long connect times but low data volumes, the key advantage of X.25 was that it provided a technique for many conversations, or data sessions, to share a communications channel. Because of when X.25 was created, it was based on an analog network infra- structure. A big problem with analog networks is the accumulation of noise through the amplification points, which leads to the very high error rate associated with analog networks. One of the value-added services provided by X.25 networks was error control as a function within the network. Because packet switching is a store-and-forward technique, at every intermediate node at which an X.25 packet would be halted, the packet would undergo an error check. If everything in the packet was correct, the intermediate node would return an acknowledgment to the original transmitting node, requesting it to forward the next packet. If the packet the node received was not correct, the node would send a message requesting a retransmission. Thus, at any point in the routing and relaying of those packets, if noise contributed to errors, the errors could be resolved, which resulted in a muc