Comtech EF Data MIDAS Version 4.X NMS Configuration - Manual (Page 56)

MIDAS 4.X NMS Configuration, Rev.6
2–28 Setup and Operation
For systems with large inclined satellites orbits e.g. 3 ° inclination, and
networks where nodes have maximum large latitude differences (say in
the order of 10
° ), a guard time or an open loop burst synchronization
strategy should be employed.
These parameters, permanently stored in the NMS database and sent to the
network elements (nodes) when they are enabled, are stored in static RAM of
the DAC.
When there has been a response (or a request) that goes unacknowledged by
the NMS, these parameters control the minimum and maximum amount of
random backoff (delay in slots, referenced to a system timing signal received
from the outbound control channel) that the DAC will wait before attempting
to re-transit the unacknowledged message.
The minimum and maximum amounts of backoff are used to tune the inbound
control channel efficiency, regulating the re-transmission of messages to a time
which is not too soon, nor too long, after transmission of a message would
normally occur. This prevents further collisions without excessive delays for
the successful re-transmission of any one message.
The node receives the following configuration information from the controller:
No Ack Count = 12 + Min Backoff
Min Backoff = 0
Max Backoff = Max Backoff – Min Backoff
IMPORTANT
After setting all of the Control Channel parameters, click Apply and then Exit.
The MIDAS NMS will then reboot. This will take several minutes to apply all of
the NMS Parameter changes.
After MIDAS System has successfully rebooted, the database will need to be
re-synced. From the MIDAS window, click Configuration Management,
highlight Controller Administration, and then click Edit and Apply to re-sync
database
.