Frame Relay is an International Telecommunication Union Telecommunications Standardization Sector (ITU-T) and American National Standards Institute (ANSI) standard. Frame Relay is a packet-switched, connection-oriented, WAN service. It operates at the data link layer of the OSI reference model. Frame Relay uses a subset of the high-level data link control (HDLC) protocol called Link Access Procedure for Frame Relay (LAPF). Frames carry data between user devices called data terminal equipment (DTE), and the data communications equipment (DCE) at the edge of the WAN.

Originally Frame Relay was designed to allow ISDN equipment to have access to a packet-switched service on a B channel. However, Frame Relay is now a stand-alone technology.

A Frame Relay network may be privately owned, but it is more commonly provided as a service by a public carrier. It typically consists of many geographically scattered Frame Relay switches interconnected by trunk lines.

Frame Relay is often used to interconnect LANs. When this is the case, a router on each LAN will be the DTE. A serial connection, such as a T1/E1 leased line, will connect the router to a Frame Relay switch of the carrier at the nearest point-of-presence for the carrier. The Frame Relay switch is a DCE device. Frames from one DTE will be moved across the network and delivered to other DTEs by way of DCEs.

Computing equipment that is not on a LAN may also send data across a Frame Relay network. The computing equipment will use a Frame Relay access device (FRAD) as the DTE.

Web Links Frame Relay http://www.cisco.com/univercd/cc/ td/doc/ cisintwk/ito_doc/ frame.htm