Installing the Junghanns.NET ISDNguard
======================================
	
- Connecting the cables
=======================

    Scenario A (Integration of an ISDN PBX):
    ========================================
    If an ISDN PBX is integrated with Asterisk into the new VoIP world
    the Asterisk server will be placed between the telco ISDN lines and
    the existing ISDN PBX. In the case of Asterisk failing the ISDN PBX
    would be inoperable. To work around this single point of failure the
    Junghanns.NET ISDNguard can be used as follows:
	- connect the telco ISDN lines to the "ISDN NET" ports
	- connect the ISDN PBX to the "ISDN CPE/PBX" ports
	- connect the serial heartbeat cable to the Asterisk server

    If you are connecting ISDN PRI lines (or ISDN BRI lines NOT using a
    Junghanns.NET octoBRI PCI ISDN card)
	- connect the Asterisk TE/CPE ports (those that should be connected
	  to the telco ISDN lines) to the "Asterisk CPE" ports
	- connect the Asterisk NT/NET ports (those that should be connected
	  to the ISDN PBX) to the "Asterisk NET" ports
    
    If you are connecting ISDN BRI lines using a Junghanns.NET octoBRI PCI
    ISDN card
	- do not connect any ports to the "Asterisk CPE" and "Asterisk NET"
	  ports
	- jumper the first 4 ports of the octoBRI PCI ISDN for TE mode and
	  the other 4 ports for NT mode
	- connect the octoBRI PCI ISDN with 8pin 1-to-1 cables to the port
	  "octoBRI PCI ISDN"
    
    When the Asterisk server stops sending the serial heartbeat then the
    Junghanns.NET ISDNguard will physically connect the ISDN PBX directly
    to the telco ISDN lines. This allow applies if the ISDNguard is switched
    off or mains power fails.

    Scenario B (Failover to a backup Asterisk server):
    ==================================================
    To failover ISDN lines from an Asterisk server to a backup Asterisk
    server (hot standby) the Junghanns.NET ISDNguard can be used as follows:

	- connect the telco ISDN lines to the "ISDN NET" ports
	- connect the master Asterisk server to the "Asterisk CPE" ports
	- connect the backup Asterisk server (hot standby) to the 
	  "ISDN CPE/PBX" ports
	- connect the serial heartbeat cable to the master Asterisk server

    When the master Asterisk server stops sending the serial heartbeat then the
    Junghanns.NET ISDNguard will physically connect the telco ISDN lines directly
    to the backup Asterisk server (hot standby). This allow applies if the 
    ISDNguard is switched off or mains power fails. 


- Configuring the software
==========================
    
    There are two ways to interface Asterisk with the ISDNguard
    a) directly accesing the serial device
	- edit /etc/asterisk/watchdog.conf and add a section like:
	
	[ISDNguard-direct]
	type = isdnguard
	device = /dev/ttyS0	; serial heartbeat device
	interval = 200		; interval in milliseconds
	
	This will generate the serial heartbeat as long as Asterisk is running.
	If Asterisk is stopped or dies the serial heartbeat will stop and the
	ISDNguard will go into failover state (indicated by the red blinking
	LED).
	
	
	b) using the ISDNguard daemon
	- edit /etc/asterisk/watchdog.conf and add a section like:
	
	[ISDNguard-with-daemon]
	type = isdnguard
	device = /var/run/guard.ctl	; fifo to the daemon
	interval = 200			; interval in milliseconds
	
	- start the ISDNguard BEFORE starting Asterisk:
	
	/usr/sbin/ISDNguard /dev/ttyS0 &	    
    
	Until now the behaviour is identical to the direct access of Asterisk
	to the ISDNguard. If you want to prevent the ISDNguard from going to
	failover state while stopping or restarting Asterisk (so it wont reset
	layer 1 on your PRI eventually triggering an alert at your telco)
	you can autogenerate the hearbeat:
	
	echo "AUTO" > /var/run/guard.ctl
	
	and then stop or restart Asterisk. You can revert to normal mode by:
	
	echo "START" > /var/run/guard.ctl
	
	Or totally prevent serial hearbeat generation with:
	
	echo "STOP" > /var/run/guard.ctl