Frame Relay to ATM Interworking

Abstract

The history of Frame Relay (FR) takes us back to 1976, when X.25 was created. X.25 specifies the interface between a terminal and a packet-switched data network. Packet switching is well suited to data transmission because of its ability to statistically multiplex packets intended for different physical destinations over a single physical link, thus eliminating the problem of needing ~N ² number of access lines for interconnecting N sites. An additional benefit of sending a data stream in packets is that it is easy to detect errors at the destination by means of checksums, and to overcome errors using packet re-transmission. In the 1970s the transmission paths used were analogue and suffered high error rates, which made error correction on a link-by-link basis desirable (as it is inefficient to propagate errored packets through the network). X.25 takes these considerations into account, but the complex protocol processing used tends to limit the maximum data rates available and to incur relatively large end-to-end delays.