In Frame Relay implementation, the connection between a DTE (router) device and a DCE (Frame Relay switch) device consists of both a physical layer component and a link layer component:
i. The physical component defines the mechanical and electrical specifications for the connection between the devices.
ii. The link layer component defines the protocol that establishes the connection between the DTE device, such as a router, and the DCE device, such as a switch.
When interconnection between LANs are implemented using frame relay, the LAN Gateway router (DTE) is connected to the Frame Relay switch (DCE) through a serial connection such as a T1/E1 leased line, at the nearest point-of-presence (POP) or WAN edge
Network switches move frames from one DTE across the network and deliver frames to other DTEs via DCEs. Other network computing equipment that is not on a LAN may also send data across a Frame Relay network by using a Frame Relay access device (FRAD) as the DTE.
The FRAD is sometimes referred to as a Frame Relay assembler/dissembler and is a dedicated appliance or a router that is configured to support Frame Relay. It is located on the customer’s premises and connects to a switch port on the service provider’s network. In turn, the service provider interconnects the Frame Relay switches.
i. The DTE (router) sends frames to the DCE (Frame relay Switches) on the WAN edge
ii. The frames moves from switch to switch across the WAN to the destination DCE (frame relay switch) on the WAN edge
iii. The destination DCE delivers the frames to the destination DTE