Frame Relay is a connection-oriented data-link technology that is streamlined to provide high performance and efficiency. For error protection, it relies on upper-layer protocols and dependable fiber and digital networks. Frame Relay defines the interconnection process between the router and the service provider
local access switching equipment. It does not define how the data is transmitted within the Frame Relay service provider cloud.
Devices attached to a Frame Relay WAN fall into the following two categories:
Data terminal equipment (DTE): Generally considered to be terminating equipment for a specific network. DTE devices are typically located on the premises of a customer and may be owned by the customer. Examples of DTE devices are Frame Relay access devices (FRADs), routers, and bridges.
Data circuit-terminating equipment (DCE): Carrier-owned internetworking devices. The purpose of DCE devices is to provide clocking and switching services in a network and transmit data through the WAN. In most cases, the switches in a WAN are Frame Relay switches.
Frame Relay provides a means for statistically multiplexing many logical data conversations (referred to as virtual circuits [VCs]) over a single physical transmission link by assigning connection identifiers to each pair of DTE devices. The service provider switching equipment constructs a switching table that maps the connection identifier to outbound ports. When a frame is received, the switching device analyzes the connection identifier and delivers the frame to the associated outbound port. The complete path to the destination is established prior to the transmission of the first frame