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QMultiFlex-400™ Installation and Operating Handbook
If a 1:1 switch over does not happen, for example when the same condition affects both
modems in the 1:1 pair, a Geo switchover is initiated.
It is recommended that the 'Transmit fail switchover' setting is enabled. Transmit or Unit
fault alarms will cause a 1:1 switchover. If the 'IP1 port down alarm' is enabled on the
Edit/Unit/Alarms menu, a switchover will occur if the IP traffic Ethernet cable is
disconnected.
If both modems at the Geo main site have the same fault (e.g. IP traffic port down on both
modems) or a 1:1 switchover cannot happen due to maintenance, the system will
switchover to use the peer Geo site.
Failure Mode 6:
Monitoring:
Actions:
Config variables
/ Timeouts:
Graphical Representation of Failure Modes
8.5.4
Start-up condition
The Modem will start-up in Geo standby with the carrier disabled. If the Modem is stand-
alone or 1:1 main, it will start pinging the Monitor IP address. If successful there will be a
delay of 30 seconds to ensure that the monitor demodulator will have locked if a signal is
present. The normal Geo Redundancy software routine will then start. If the peer site is
running as main, this site will remain in standby until a switchover condition is detected. If
the Monitor IP address does not respond, a 'No response from Monitor IP address' alarm
is raised and the system will continue to test the Monitor IP address until it responds.
8.5.5
IP Messaging
Both modems in a Geo pair continually send messages at approx rate of 1 per second. The
message consists of a UDP datagram containing whether the modem has detected a failure
and whether the modem's carrier has been muted by Geo control software. These
messages will be addressed to an M&C address. If a 1:1 pair is in use, both 1:1 'peer' M&C
addresses are used.
8.5.6
Restrictions
•
When using the Geo-Redundancy feature, one of the sixteen demodulators is
used for self-monitoring purposes. Using demod 1 is recomended.
•
The hub modem must be able to receive its own Tx carrier from satellite.
•
The maximum hub Tx symbol rate is limited to 40Msps, as this is the limit of an
individual demodulator on QMultiFlex-400™.
•
All carriers must fit inside a contiguous 72MHz of bandwidth.
•
Use with expanded (cascaded) systems is not currently supported, so the
maximum number of remote sites is fifteen.
•
IP Routing mode is not supported.
1:1 failure
Modem alarms
•
If active fault level alarms then delay to allow 1:1 switchover
•
Switch to Geo standby if still 1:1 Main
1:1 delay (15s)
8-34
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