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Configuring Frame Relay
This feature is supported only on the following modules:
• CE3.
• CPOS.
• CT3.
• E1.
• E1-F.
• POS
• SAE.
• T1.
• T1-F.
Overview
Frame Relay uses statistical multiplexing technology and can establish multiple virtual circuits over a
single physical cable to make full use of network bandwidth. Frame Relay uses data link connection
identifiers (DLCIs) to identify virtual circuits. Frame Relay uses the Local Management Interface (LMI)
protocol to maintain the status of each virtual circuit.
The following interfaces support Frame Relay:
• Synchronous serial interfaces, including synchronous serial interfaces derived from other interfaces.
• POS interfaces.
Frame Relay interface types
As shown in Figure 71:
• A Frame Relay network provides data communications between user devices such as routers and
hosts. The user devices are also called data terminal equipment (DTE).
• The devices that provide access to the Frame Relay network for DTEs are called data
communications equipment (DCE).
Frame Relay interfaces include the following types:
• User-to-network interface (UNI)—A DCE is connected to a DTE through UNI interfaces. UNI
interfaces include the following types:
{ DTE interface—The UNI interface on the DTE side.
{ DCE interface—The UNI interface on the DCE side.
• Network-to-network interface (NNI)—A DCE is connected to a Frame Relay switch in the Frame
Relay network through an NNI interface. The switches in the Frame Relay network are
interconnected with NNI interfaces.
A DTE interface can connect only to a DCE interface, and an NNI interface can connect only to an NNI
interface. On a Frame Relay switch, the Frame Relay interface type must be NNI or DCE.
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