Frame Relay History
Frame Relay is a Wide Area Network (WAN) protocol that operates at the physical and data link layers of the OSI reference model. Frame Relay originally was designed in the early 1980s for use across Integrated Services Digital Network (ISDN) interfaces. Today, it is used over a variety of other network interfaces as well. Frame Relay often is described as a streamlined version of X.25, offering fewer of the robust capabilities, such as windowing and retransmission of last data that are offered in X.25. This is because Frame Relay typically operates over WAN facilities that offer more reliable connection services and a higher degree of reliability than the facilities available during the late 1970s and early 1980s that served as the common platforms for X.25 WANs. Frame Relay is strictly a Layer 2 (under TCP/IP) protocol suite, whereas X.25 provides services at Layer 3 (the network layer, like IP). This enables Frame Relay to offer higher performance and efficiency than X.25, and makes Frame Relay suitable for current WAN applications, such as LAN interconnection or private networks.