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Frame Relay Devices

All Frame Relay devices that can attach to a Frame Relay WAN fall into only two general categories:

• DTE

• DCE

DTE

DTE is commonly the terminating equipment for a specific network that communicates directly with an end user or network. DTE typically is located on the customer premises, usually close to the SP's demarcation point. DTE usually is owned and operated by the customer.

DCE

DCE provides clocking and switching services in a network. The DCE converts user data from your DTE into an acceptable form for the WAN service facility. DCEs are usually the carrier-owned internetworking devices that are responsible for the transmission of data in the WAN. Figure 9-2 illustrates the relationship between a DCE and DTE.

Relationship Between DTE and DCE

The connection between the DTE device and the DCE device exists as a physical layer component, but it also contains a link layer component. The link's physical layer component defines the specifications used to connect the devices. The link's link layer component specifies how the connection is established between the DTE device and the DCE device.

The DTE/DCE interface is typically used to identify the boundary of responsibility for the traffic passing between you and your service provider. The physical standards used to specify the DTE/DCE interface include EIA/TIA-232, X.21, EIA/TIA-449, V.24, V.35, and HSSI (Cisco-proprietary).

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