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QMultiFlex-400™ Installation and Operating Handbook
The M&C IP addressing will use unique IP addresses. The QMultiFlex-400™ will monitor
the remote addresses of the other site as well as a highly available IP address.
The Hub sites will use one of the Multi Demodulators to allow the Tx outbound carrier for
either site to be monitored. This requires all equipment operated over the satellite link to be
able to monitor the other Hubs Tx signal. The Standby site will disable its packet output &
traffic port IP addresses.
8.5.2
Geographical Redundancy Integration with 1:1 redundancy
In general, a modem in 1:1 standby does not participate in the Geo redundancy system
and is not sending messages to the 'other' Geo site, but it should still listen to the messages
from the other Geo Site and update its internal state so that it is ready to resume sending
messages on a 1:1 switchover.
Modem alarms will generate a 1:1 switchover which should be preferred to a Geo
switchover. When an alarm is detected by monitoring the '1:1 statIn signal', a delay is added
before a Geo switchover is initiated, to allow the other modem in the 1:1 pair to take over.
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 will happen.
8.5.3
Geographical Redundancy Hub Failure Modes
Six failure modes are considered, these modes are graphically shown in Figure 8-26. A
dual 1:1 system is presented to show all six failure modes.
8-30
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