Comtech EF Data VMS v3.12.x Vipersat - Manual (Page 458)

General MN/22156, rev 12
E-2 VMS User Guide
back to these intelligent modem/routers, effectively managing the Vipersat
network operation in real time, and optimizing each site’s bandwidth usage to
meet their QoS and cost requirements within their bandwidth allocation. The
result is a stable satellite network connection that automatically responds to the
customer’s requirements while continuously monitoring and reacting to chang-
ing load, data type, and QoS requirements.
Hitless Switching
Unless inherent delays in configuring both ends of a satellite bandwidth link
during dynamic switching are accounted for, transmitted data may be lost
during the transition. The time for a switch command to be sent across the satel-
lite link (~ 250 ms), the command processing time, as well as receiver acquisi-
tion time must be considered. The Vipersat Hitless Switching feature provides
a means to coordinate timing and utilize buffering to eliminate these data
outages.
The parameters for configuring the Hitless Switching feature for a CDM-570/
570L are set from the screen shown in figure E-2. This screen is accessed from
the STDMA/SCPC Auto Switching screen (see figure E-3 and figure E-5).
Figure E-2 Hitless Switching screen
• Enable/Disable – The Hitless Switching screen will initially display all
lock times as -1, indicating that the feature is disabled. The Restore
Default Lock Times command is used to enable this feature.
• Delay for Mod – This parameter allows the operator to insert additional
delay to buffer more data after modulator transmission is ceased.
• Delay for Demod – This parameter allows the operator to insert additional
delay to account for the tuning of the demodulator.
• LockTimes – LockTime settings for the four data rates displayed can be
adjusted either up or down, but default settings based on satellite testing