AT&T DS1/DMi/ISDN-PRI manual Port TYPES/INSTALLATION Compatibilities

6. PORT TYPES/INSTALLATION COMPATIBILITIES

This chapter describes the operating modes, installation compatibilities, and port types supported by DS1s. Because of differences between Generic 1 and Generic 2 software and hardware, appropriate distinctions are identified and separate sections provided.

To date, DS1s have been well accepted. For both Generic 1 and Generic 2, DS1s were initially available for providing digital tie trunks. Later versions of DS1s and later releases and versions of the switch software provide additional capabilities. These later version circuit packs are always backward compatible with previous types.

However, new capabilities that depend on software may only be available on the earlier releases when the required software is provided, whether the software is a patch or later issue of the tape. Not all new capabilities are backward compatible to earlier releases and versions. Table 6-1,Supported Digital Facilities, lists the available capabilities and the hardware and software dependencies.

Engineering problems are minimized by having a good understanding of:

●DS1/DMI, and ISDN-PRI capabilities

●Hardware and software compatibility requirements

●Services that the particular application requires

●All carrier facilities that will be used to complete the end-to-end transmission facility (both local exchange company (LEC) and toll network carrier)

●The labeled network diagram

Installation problems are minimized by proceeding from a labeled network diagram. Each DS1 or all intermediate transmission equipment, such as channel-expansion multiplexers (CEMs), channel- division multiplexers (CDMs), network channel-terminating equipment (NCTE), network carrier multiplexers, channel banks, or channel units, should be verified for compatibility. Verification includes a review of the administration options and, where appropriate, the option-switch settings.

Each end of the channel must be fully compatible For example, if at one end channel 1 is used as a tie trunk, then channel 1 at the distant end must also be used as a tie trunk. Or, if a group of channels (for example, 1-16) are administered for call-by-call (CBC) use at one end, then the same group of channels must also be used for call by call. If, at one switch, extended super framing (ESF), 24th-channel signaling, and the zero code supression (ZCS) line-code format are optioned, then the distant end and all intermediate facilities must be administered or optioned likewise.

CAUTION: The 551V channel service units will only function with the ZCS line-code format. They will not pass B8ZS bipolar violations. If the B8ZS line-code format is used for copper carrier facilities, then the 551V ST (or equivalent) NCTE should be installed and optioned accordingly.

The CDMs are T1 multiplexers that provide an economical means to independently access any of the 24 channels from a DS1 or T1 facility. This access means is called per-channel drop and insert capability. One line-interface unit, the CDM DS1, connects to the compatible equipment (such as, a

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