The Data LinkChannel Identifier (DLCI) is a header field in the Frame Relay frame that specifies the permanent virtual connections (PVC) and the elected virtual connections (SVC) and contains the virtual channel numbers.
DLCI is a connection identifier used to identify the local endpoints of a virtual connection. The DLCI field is read and evaluated by the network nodes. By using different DLCIs on one and the same physical channel, different connections to different destinations can be realized simultaneously.bits (16 bits or 23 bits), with which 1,024 addresses could be addressed. Since some addresses are reserved for signaling tasks, about 875 logical channels can usually be addressed. In the DLCI field, there is a bit, the DL-Core Control Indicator Bit (DC), which indicates the function of the rear DLCI subfield.