Lucent Technologies 555-230-024 Digital Communications Protocol, Digital Multiplexed Interface

Digital Interfaces

Digital Communications Protocol

Digital Communications Protocol (DCP), a forerunner of ISDN-Basic Rate Inter- face, has been the architectural foundation for Lucent Technologies digital serv- ers and switches. It provides advanced ISDN-like functions by integrating voice and high-speed data. DCP continues to serve as a key digital interface for

DEFINITY ECS.

Like ISDN-Basic Rate Interface, DCP defines the communications interface between a terminal and the switch. It consists of two 64-kbps information (or bearer) channels and a separate 8-kbps channel for signalling and control infor- mation (or data channel). Out-of-band signalling via the data channel allows the information channels to be used for clear-channel transmission.

DCP’s framing structure allows voice, data, and signalling information to be trans- mitted with low overhead and virtually free of errors. DCP transmits at a rate of 8,000 frames per second or 160 kbps. DCP allows data and digitized voice to be multiplexed on one or two twisted pairs, terminating in a standard telephone jack.

Digital Multiplexed Interface

DEFINITY ECS supports high-speed, efficient data communications through Lucent’s Digital Multiplexed Interface. Digital Multiplexed Interface allows com- munications between a terminal and host computer, between a switch and host computer, and between two host computers.

Digital Multiplexed Interface is consistent with ISDN-PRI. 24 64-kbps channels (one of which is reserved for signalling information) transfer data between two endpoints through the DEFINITY ECS. The multiplexed channels can be sent over standard Digital Signal Level 1 facilities, allowing the host computer to be located remotely.

Digital Multiplexed Interface offers two major advantages. It delivers a standard, single-port interface for linking host computers internally and externally via T1 carrier. And, since it is compatible with ISDN standards and is licensed to numer- ous equipment manufacturers, it promotes multi-vendor connectivity.

DEFINITY ECS supports two versions of Digital Multiplexed Interface, each differ- ing in the way information is carried over the 24th channel:

■Digital Multiplexed Interface-bit-oriented signalling carries framing and alarm data and signalling information for connections to host computers and other vendor equipment.

■Digital Multiplexed Interface message-oriented signalling, fully compatible with ISDN-PRI, uses the same message-oriented signalling format, Link Access Procedure on the D-channel, as ISDN-PRI for control and signalling. These signalling capabilities extend the advantages of Digital Multiplexed Interface-Message Oriented Signalling multiplexed communications to the public ISDN network.

555-230-024 Issue 5 January 1998 8-5