Architecture
C-DOT switches have a distributed architecture.
A Base Module(BM) has 512 ports which can
provide non-blocking connectivity and can accept
concentrated subscriber lines. The BM, capable
of serving upto 2000 lines or 512 trunks, is
used as the basic building block. Each BM is
housed in a single cabinet. By interconnecting
upto 32 such BMs through a Central Module(CM),
the switch can support upto 40,000 lines. The
system can support upto 4:1 concentration. Lines
and trunks can be inter-mixed in the same BM.
The front-end of the system consists of an
Input Output Processor(IOP) connected to the
Administration Processor (AP). Each system
consists of two IOPs working in duplex mode.
IOP, based on Motorola 68040 and supporting UNIX
environment, provides interface for the man
machine communication, system initialisation
support, operator features etc.
The switch is capable of Local, Trunk and
Integrated-Local-cum-Transit applications. It is
meant to provide cost-effective solution for
metropolitan needs. There is a commonality of
hardware, software, features and facilities,
packaging, operations and maintenance etc, in
all MAXs.
Hardware
A BM can support upto 16 Terminal Units(TUs),
each handling 128 terminations. A serive
Unit(SU) caters for service functions like tone
generation, MF/DTMF singalling etc. The switch
is controlled by Motorola 68010/68040. In the
periphery, one 8-bit microprocessor controls 128
terminations. The system has a high redundancy -
all hardware excluding line/trunk terminations
are duplicated to provide a very high system
reliability. The switch uses less than 40 card
types. The controllers communicate through a
Base Message switch (BMS) via 64 kb/s HDLC
links. The switch is highly connectorised with
minimal inter-frame wiring. Low power CMOS
technology ensures low power consumption. The BM
is convection cooled and the CM is forced
air-cooled.
The major function of CM is to provide voice
switching between the BMs and enable
communication of control messages between
different parts of the system. The AP supports
the global routing and translation functions.
Software
The software is distributed across the 16-bit
and 8-bit controllers of the system. Majority of
the software real time functions are handled at
the BM level. Only minimal real time functions
are handled at AP. The BP handles call
processing, administration and mainetenance
functions relating to the terminations connected
to that BM. Majority of the realtime software
runs under a custom built real time operating
system called CDOS. The software is implemented
as Modular communicating processes using 'C'
language.
Technical Specification:
