Comtech EF Data VMS v3.12.x Vipersat - Manual (Page 444)

N:M Hub Modem Redundancy MN/22156, rev 12
C-34 VMS User Guide
2. When an event is detected that requires a redundancy switch, VMS sends a
notification event to the VMS Log service.
3. VMS sends notification to the Redundancy Manager that a switch-over is
required.
Redundancy Manager
The Redundancy Manager receives the switch-over request from VMS which
starts the following process:
1. The Redundancy Manager checks that the VMS notification is a for a valid
switch condition. If the condition is not valid, the Redundancy Manager
sends its action to the VMS log service and returns to waiting for the next
event notification.
2. If the notification is a valid switch condition, the Redundancy Manager
checks to see if there is a backup unit available. If no unit is available, the
Redundancy Manager send this information to the VMS Log Service and
returns to waiting for the next event notification.
3. If there is a backup unit available, the Redundancy Manager sends a com-
mand to the remote managed power control unit to turn off power to the plug
used by the failed primary unit.
4. The Redundancy Manager saves (puts) the redundant configuration and base
modem parameters to the backup unit.
5. The Redundancy Manager commands a firm reset of the backup unit.
6. After the switch, the backup unit is configured as the original primary unit
and joins the network performing the same functions as the failed primary
unit.
7. When the unit switch-over is completed, the Redundancy Manager sends the
event to the VMS Log service, completing the switch-over process.
8. The Redundancy Manager resumes waiting for the next event notification.
Putting Failed Unit Back into Service
This section describes the process of configuring a VMS controlled modem
before connecting it to a VMS network as an N:M redundant backup unit.