DLCI

A data link connection identifier (DLCI) is a channel number which is attached to data frames to tell the network how to route the data.

Frame relay is statistically multiplexed, which means that only one frame can be transmitted at a time but many logical connections can co-exist on a single physical line. The DLCI allows the data to be logically tied to one of the connections, so that once it gets to the network it knows where to send it.