Data link connection identifier

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. Frame Relay networks use DLCIs to statistically multiplex frames. DLCIs are preloaded into each switch and act as road signs to the traveling frames.^[1]

The standard allows the existence of 1024 DLCIs. DLCI 0 reserved for ANSI/q993a LMI standard - only numbers 16 to 976 are usable for end-user equipment. DLCI 1023 is reserved for Cisco LMI - however, the numbers usable are from 16 to 1007. ^[2]

In summary, only numbers from 16 to 1007 are available for end users' equipment (If using Cisco LMI). The rest are reserved for various management purposes.^[3] Take note that DLCI are Layer 2 Addresses that are locally significant. No two devices have the same DLCI mapped to its interface in one frame relay cloud.

References

1. ↑ "DLCI's". Retrieved 22 March 2011. 
2. ↑ "Frame Relay LMI". Retrieved 2014-04-24. 
3. ↑ "What is Frame Relay". Retrieved 2007-09-18.