Data link connection identifier

A DLCI is a unique number assigned to a virtual circuit endpoint in a frame relay network for the addressing purpose.

A DLCI uniquely identifies a particular virtual circuit on a physical link and has local significance only to that link. A DLCI can be used on different physical ports to address different virtual circuits. A virtual circuit between two DTE devices can be addressed with different DLCIs at the two ends, as shown in Figure 23.

Because the virtual circuits in a frame relay network are connection oriented, each DLCI on a physical port is destined for a distinct remote device. DLCIs can be regarded the frame relay addresses of remote devices.

The maximum number of PVCs that can be created on a frame relay interface is 1024. The user configurable DLCIs for the PVCs are in the range 16 to 1007. Other DLCIs are reserved for special purposes. For example, DLCI 0 and DLCI 1023 are reserved for the LMI protocol to transfer control messages.