AT&T DS1/DMi/ISDN-PRI manual IBM Idnx Multiplexer to Another System

2-4NETWORK CONNECTIONS AND CONFIGURATIONS

administrable but will not work for DMI-to-host-computer applications. Current versions of the AT&T 3B5 and 3B15 computers (DMI) provide E&M trunk signaling and only support the wink- in/wink-outtrunk type.

Regarding synchronization, the computer must always derive its timing from the DMI signal received from the switch. The computer should never be used as a timing reference by the switch; this would cause each endpoint to get its timing from the other endpoint.

According to the AT&T DMI technical specification, DMI is an open-architecture interface. Therefore, the System 75, System 85, Generic 1, and Generic 2 DS1s/DMIs are compatible with other vendor computer endpoints when used in DMI applications. However, each vendor must pass a certification program to ensure compatibility and compliance.

IBM® IDNX Multiplexer to Another System

The IBM IDNX multiplexer is not a host endpoint, although it connects to a front-end processor or host computer. This is not a DMI-to-host configuration and the DMI trunk type will not work for this application. The only requirement is that 24-channel signaling and the BOS format be used. All other options, including trunk type, are application dependent.

Other Vendor Digital Switch to Another System

When a System 75, System 85, Generic 1, or Generic 2 DS1/DMI connects to another vendor's customer-premises switch (another vendor’s DS1/DMI), several items should be verified to determine compatibility:

●The interface electrical characteristics

●Options

●Synchronization capabilities

The following key questions should be answered:

●Does the vendor product provide a DSX-1 interface (see chapter 3, DS1 Transmission and Cabling)?

●Does the vendor product support at least one each of the line coding, framing, and signaling options provided by System 75, System 85, Generic 1, and Generic 2?

●Does the vendor implement AT&T ISDN specification?

●Does the vendor support DMI modes?

●For synchronization purposes, what stratum clock does the vendor switch provide?

●Will the vendor switch act as a timing master or slave time to the communications system?

●Does the vendor switch implement the digital loss plan specified by ANSI/EIA/TIA-464-A-1989?

Depending on the answers to these questions, basic compatibility can be determined. However, because System 75, System 85, Generic 1, and Generic 2 DS1/DMI are not generally tested for