A data link connection identifier (DLCI) is a Frame Relay 10-bit-wide link-local virtual circuit identifier used to assign frames to a specific PVC or SVC.
DLCIs are preloaded into each switch and act as road signs to the traveling frames.
DLCI 0 is reserved for the ANSI/q993a LMI standard—only numbers 16 to 976 are usable for end-user equipment.
[2] In summary, if using Cisco LMI, numbers from 16 to 1007 are available for end-user equipment.
No two devices have the same DLCI mapped to its interface in one frame relay cloud.