Comtech EF Data VMS v3.12.x Vipersat - Manual (Page 426)

N:M Hub Modem Redundancy MN/22156, rev 12
C-16 VMS User Guide
The spare unit is selected in order of IP address. If the spare unit fails to respond
or process, it is marked as unavailable by VMS and the VMS repeats the
process by selecting the next available unit in the list. Also, as part of the copy
command, a separate message is sent to the IP remote controlled AC power bus
removing power to the primary failed unit, shutting it down. This ensures that
there is no possible contention between the failed unit and the spare unit being
brought online.
As the spare unit receives the database configuration file it immediately copies
the image over the stored offline state parameters and issues a firm reset to rein-
itialize the newly stored information without rebooting. Once the firm reset
completes (approximately 1 second for non-STDMA mode or approximately 5
seconds for a unit operating in STDMA mode) the unit will announce itself by
broadcasting an ARP message updating local routing tables.
The failed primary unit is readily identified by its powered down state. Once the
cause of failure is identified and repaired, the primary unit can be reinstated and
put back online using the procedure in the section “Putting Failed Unit Back
into Service” on page C-34.
Installing N:M Redundancy
The installation of N:M redundancy in a satellite network involves the physical
installation, interconnection, and grouping of the primary and secondary
modems and the logical grouping of managed units using the VMS Redundancy
Manager.
Hub N:M Redundancy Requirements
The following requirements must be met before you can do a successful instal-
lation of VMS N:M redundancy.
• N:M Redundancy is only applicable to Hub devices that are not expansion
units
• The VMS version must be 3.x or later
• VMS controlled modems must have identical firmware version installed.
• A Server Technology horizontal Sentry™ PowerTower XL IP remote
power control is required
• The active device and the backup device must be connected to the same
Ethernet LAN
• The active and backup devices must be connected to the same RF output
connection