Digital loop carrier
Like any loop carrier, the SONET digital loop carrier (DLC) minimizes the assignment of dedicated plant to the loop environment. Considered a special-purpose TM, the DLC gathers analog or digital signals from a variety of users and combines them onto a SONET link to bring the benefits of fiber closer to the end user.
DLCs consist of remote terminals and CO terminals. The attraction of SONET DLCs is that they enable using remote terminals from one vendor with CO terminals from another vendor. All of the OAM&P features of SONET are supported by the DLC.
SONET DLCs are sometimes called next-generation DLCs (NGDLC). Some newer NGDLC prototypes enable direct inclusion on SONET rings. Other prototypes have experimented with cross-connecting in the NGDLC itself.