Comtech EF Data SLM-5650A Vipersat - Manual (Page 107)

Appendix B - Automatic Switching B-9
Load Switching
Load Switching—Remote
Once a Remote has been switched from STDMA mode to SCPC mode, it
checks its bandwidth requirements to see if a change is needed. A running aver-
age of the data traffic passing over the WAN is maintained as a percentage of
the current data rate for the Remote. This average is accumulated for at least the
specified delay (Step Up/Step Down) period. Then, once per second, the current
utilization is checked against the Step Up and Step Down Thresholds. If the
utilization is outside the up/down range, a request is generated to switch to the
calculated rate. After the request is granted, the running average is reset and the
cycle is repeated.
Remote Switching Parameters
The parameters for controlling the Step Up/Step Down switching process are set
in the page shown in figure B-2.
Figure B-2 Remote Load Switching Page
• Load Switching – This is a type of Automatic Switching that is based on
the amount of traffic at the Remote. If this feature is not enabled, then this
Remote will not be switched based on load.
• SCPC Step Up Threshold – This is a window threshold that initiates a
load switch to a higher data rate when the amount of traffic as measured
within the transmit queue exceeds this setting. The value is specified as a
percentage of the current data rate.
Similar to the Hub parameter STDMA Slot Capacity.
• SCPC Step Down Threshold – Similar to the Step Up Threshold, except
Step Down is used to trigger a switch to a lower data rate when the average
traffic load falls below the set value.
• SCPC Step Delay – This is a built in latency that forces the Remote to
maintain an average load for the specified period (seconds) that exceeds
the switch threshold before a switch to a new data rate is actually initiated.