Local AXE10 Exchange Subsystems
hybrid <hybrid@f41th.com>
===============================

The AXE10 exchange is sometimes referred to as "System Y", and is
manufactured by Ericsson. It is modular in design and is therefore divided
into a number of subsystems. The following text describes the subsystems
in a local exchange and shows how they are interconnected. 

Basic Structure
===============

An AXE10 exchange can be split into three main parts. These are known as
APT, APZ, and IOG. As shown in the following diagram:


	+-------------------------------------------------------+
	:  .----------.	    .----------.     .----------.	:
	:  |   APT    |     |  SWITCH  |     | JUNCTION |	:
.---.---:--|->      <-|-----|->      <-|-----|-> ACCESS-|-------:-------> 
|:::|   :  |__________|     |__________|     |__________|	:
PHONE	:       |		 |		  |		:junctions
	:	| APT:		 |		  |		:
	:	| customer	 |      __________|		:
	:       | access         |     |			:
	:	|		 |     |			:
	:	|		 |     |			:
	:.......|................|.....|........................:
	:	|		 |     |       :    IOG		:
	:  .----|----------------|-----|----.  :  .-----.	:MM COMS
	:  |	     			    |  :  | I/O	|-------:------->
	:  | APZ:	CONTROL		  <-|--:--|->   |	:OMC
	:  |________________________________|  :  |_____|-------:------->
	:				       :		:ALARMS
	:______________________________________:________________|
	
	(Basic Structure of an AXE10 Exchange)
	(IOG == Input Ouput Group)

Call switching, customer acces and junction access are all handled by the
APT, while control is the responsibility of the APZ. Input and output
connections to terminals, printers, alarms, storage devices, and data
links are all handled by the IOG. This is similar to a theoretical layout
of a System X exchange type.

Subsystems
==========

The three main parts are divided into a number of subsystems, as shown in
the following diagram:


        +-------------------------------------------------------+
        :  .----------.     .----------.     .----------.       :
        :  |   APT    |     |   GSS    |     |   TSS    |       :
.---.---:--|-> SSS  <-|-----|->      <-|-----|->       -|-------:------->
|:::|   :  |__________|     |__________|     |__________|       :
PHONE   :       |                |                |             :junctions
        :       |                |                |    _______  :
        :       |                |      __________|   |  CCS  | :
        :       |                |     |              |_______| :
        :       |                |     |  ________________|     :
        :       |                |     | |                      :
        :.......|................|.....|.|......................:
	:	|		 |     | |  ___  :		:
	:	|		 |     | | |   | :		:
	:	|	 	 |     | | |   | :		:
        :  .----|----------------|-----|-|-|-. | : .-.--------. :
	:  |      	RPS		     | | : | |  MCS   |-:------->	
	:  |_________________________________| | : | |--------| :alarms
	:				       |_:_|_|  FMS   | :printers	
	:				         : |S|  IOG   | :terminals
        :  .---------------------------------.   : |P|--------| :
        :  |  APZ       CPS                  |   : |S|  DCS   |-:------->
        :  |_________________________________|   : |_|________| :OMC
	:					 :              :access
	:________________________________________:______________:

	(AXE10 Subsystems)
	(APZ control is split into Regional Processing Subsystem (RPS),
	 and the Central Processing Subsystem (CPS)).

APT contains the:
(APT Subsystems)
	
Subscriber Switching Subsystem (SSS) to provide customer access
===============================================================
The SSS has the same function as the DSSS in System X and concentrates
customers lines into a number of digital (PCM) links. It can be sited in
an AXE10 exchange where it is called a Local Subscriber Switch (LSS) or in
a remote location where it is called a Remote Subscriber Switch (RSS). As
with System X remote concentrators (RCUs), the collection of RSSs on one
site is called a Remote Concentrator Centre (RCC).

Trunk and Signalling Subsystem (TSS) which deals with junction access
=====================================================================
TSS handles the connections to other exchanges. Its main job is to match
the AXE10 exchange to various junction signalling systems. It is similar
in function to the SIS subsystem in System X.

Group Switching Subsystem (GSS) which handles switching
=======================================================
GSS is the heart of the switching system and is responsible for connecting
and supervising speech paths, it is similar to the DSS in a System X
exchange.

Common Channel Subsystem (CCS) which handles CCITT No 7 (C7) signalling
=======================================================================
This subsystem handles the common channel signalling messages between the
AXE10 and other exchanges. It is similar in function to the MTS in System
X exchanges.


APZ Subsystems
==============

Regional Processor Subsystem (RPS)
==================================
RPS consists of a number of Regional Processors (RPs). These processors
perform simple, routine, high capacity tasks, such as scanning of
subscribers lines and the operation of switches. The regional processors
are usually mounted next to the equipment they are serving and so are
spread around the exhange equipment.

Central Processor Subsystem (CPS)
=================================
CPS contains two processors (CPs) which carry out all the complex
processing needed to control the AXE10 exchange. The duplication of
central processors is necessary for system security. It is similar in
function to the PUS subsystem in System X.


IOG Subsystems
==============

Support processor Subsystem (SPS)
=================================
This subsystem supervises the operation of all IOF functions.

Man-machine Communication Subsystems (MCS)
==========================================
This subsystem handles communications between input/output devices and the
rest if the AXE10 exchange. These devices can be visial display terminals,
printers, or alarm panels.

Data Communications Subsystem (DCS)
===================================
This subsystem handles communications over digital links e.g. (in the UK:
OMC etc). MCS and DCS have approximately the same function as the AUS and
NIS subsystems in System X.

File Managment Subsystem (FMS)
==============================
All mass storage devices (backing stores) are connected via the FMS
subsystem. These devices can take the form of tapes, floppy disks and hard
disks. In System X this function is part of the PUS subsystem.


What an AXE10 Exchange l00ks like
=================================

Inside a typical AXE10 exchange will be rows of cabinets containing 1 
or 2 AXE10 Central Processor Racks (containing mounted magazines, cards
and cables). 1 or 2 IOG11 cabinets (narrow looking cabinets with just 1
door).


Deployment
==========

Most of Greece, especially populated areas such as Athens is served by
AXE10 and System Y subsystems. In the UK there are ISCs (International
Switching Centres) which handle traffic to and from other countries, such
as: Keybridge, Kelvin, Madley which are using AXE10 for international
trunking and supervision.

Managment
=========

AXE10 MCS Man Machine Interfaces control the functionality of the AXE10
system. To list every "function" that is available in the Ericsson AXE10
command line would take forever, just for a tase of what these commands
look like, here is an example of a MONITORING command line descrition.

MONITORING, INITIATE
====================
		 
		 +         +	     + +
      +	       + | DEV=dev | BCH=bch | |	// command format.
MONTI:|BNB=bnb,| +         +'        + +;
      +        + | SNB=snb	       |	
		 +		       +

// parameters

BCH=bch		B-channel identity. Numeral with value 1-30. Used to
		initiate monitoring on a specific B-channel at
		applications where one device corresponds to one access.

BNB=bnb		B-number for listening or speech connection to test
		position. Digit string 1-16 digits where each digit is
		0-9 or #10-#15.

DEV=dev		Device designation. Expressed as dety-n where dety: a
		device type identfier 1-7 characters (system defined) n:
		Numeral 0-65535. The maximum value is defined by SAE=500
		in the block which ownz the device. Alternate expressions
		can be found in the appliocation information for block
		TRAN and the concerned device block.

SNB=snb		Subscriber number. Digit string 1-12 digits where each
		digit is 0-9 or #10-#15. The maximum number of digits can
		be found in the application information for block TRAN.

Dialogue Parameters
===================

CON;		Executes trunk offering of the monitored object. This
		cannot be given if offering with speech facility has 
		already been executed.

END;		Disconnects the monitoring function and terminates the
		dialogue command.

NXT;		Initiates monitoring of the next channel of the monitored
		object. This can only be used if there is more than one
		channel for the monitored object and where BCH has not
		been specified. It may only be given after a monitoring 
		connection has been established.

SON;		Executes trunk offering with speech facility of the
		monitored object.

The function
============

In dialouge with the function, the command orders trunk offering in GS for
monitoring of an ESTABLISHED CALL. The command can only be ordered and
executed from a defined test position in the exchange.  The function is
able to handle monitoring of successive channels of ISDN subscriber lines
with more than one channel. Trunk offering is not permitted for certain
subscriber catigories.

In applications where one device corresponds to one primary rate access,
it is possbile to innitiate monitoring of a specific B-channel by the
paremter BCH. If paremeter BCH is not specified then monitoring is
performed on the first busy channel. 

If the operator wishes to enter the line with conversation about the
monitored call, this can be done with the paremter SON, in which case the
printout SPEECH MONITORING ESTABLISHED will be recieved. 

Monitoring of subscriber number 9900220: (example)

	(<)MONTI:SNB=9900220;
	(READY FOR CONNECTION)
	(:) CON;
	(CONNECTION ESTABLISED)
	(:) SON;
	(SPEECH MONITORING ESTABLISHED)
	(:) END;
	(CONCLUSION OF COMMAND MONTI)


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