Comtech EF Data CRS-200 - Manual (Page 38)

Setup Guide CRS-200 Redundancy Switch
6–6 Rev. 1
6.4 Additional Switch Configuration
Once all IF cabling is complete, the system should be completely operational but still in
Manual mode. The user may choose to operate in this manner, but the switch will not
automatically react to traffic modem failures it detects. If the system is to be left
unattended, it is recommended that the user go to the “CONFIG, AUTO” menu and turn
on Auto mode.
The Stored Event LED will stop blinking, and now the switch will force the redundant
modem to bridge, then back up the first activated modem which fails. Two other
configuration options are useful for fine tuning the switch’s Auto mode, and are
described next.
6.4.1 Holdoffs
When in Auto mode, additional delays may be introduced to the backup procedure by
going to the “CONFIG, OPTIONS, HOLDOFFS” menu and changing the “backup
holdoff” from its default of 5 seconds to anywhere from 2 to 99 seconds. When a traffic
modem fails and the redundant modem is forced to “bridge” it, the switch waits this
length of time to determine two things: does the traffic modem remain faulted, and is the
redundant modem not exhibiting the same fault? If the answer to both questions is “yes”
for the entire holdoff time, the switch performs the actual backup.
The “restore holdoff”, which is also programmable from 2 to 99 seconds, determines the
switch’s ability to automatically put a backed up traffic modem online again if its fault
goes away. Normally, a failed modem that was taken offline will remain offline
indefinitely even in Auto mode unless another traffic modem fails. In this case, the
originally failed modem will be put back online by the switch if its fault has been clear
for the full programmed restore holdoff time. The redundant modem can then be used to
backup the newly failed modem. The switch has no prioritization scheme, so that
multiple traffic modem failures are treated on a ‘first come, first serve’ basis only.
6.4.2 Alarm Mask
Another way to adjust the switch’s reaction in Auto mode is to mask modem faults.
Under “CONFIG, OPTIONS, ALARM-MASK, MODEM-ALARMS”, the user may
disable Tx, Rx or both faults from being seen by the switch. This not only prevents the
switch from taking automatic action, but also keeps the faults from being logged on its
stored events list. Note that these masks are global to all the modems attached to the
switch. Note also that each modem can be individually programmed with its own set of
alarm masks.
NOTE
Please read this Operations Manual in conjunction with the Operations Manual for the CDM-500, CDM-
550, or CDM-550T as details of the operation of the Modem equipment is not covered in this document.