System 5000 Common Management Bus - Bay Networks 5393 Hardware Installation Manual

PCM Codec

System 5000 Common Management Bus

The Remote Annex uses PCM codecs to convert the analog signals
coming from the modems into 8-bit serial data streams. The data
streams are multiplexed and passed to the ISDN PRI interface along
with data that is purely digital in nature, such as that used with V.120
and synchronous PPP protocols.
The management section of the backplane is the common
management bus (CMB), a high-speed, multimaster, shared-memory
communication channel that connects all modules installed in the hub
to one another and to the supervisory module. The modules installed
in the hub use the CMB to acquire and distribute configuration and
status information.
The supervisory module is an intelligent interface between the Model
5000 chassis and user-installed modules. The supervisory module
provides the following services to other modules across the CMB:
Maintains chassis component information and
environmental status
Stores the primary module configurations
Restores the module configuration after the module power
is cycled or the module is reset
The supervisory module also supports configuration terminal
support through the service port on the front panel of the chassis.
Remote Annex 5393/PRI Hardware Installation Guide
Chapter 1 Introduction
1-5