User guide

Appendix B - Automatic Switching B-7
Load Switching
as the network is running below capacity, most Remotes will get the bandwidth
they need and a switch will not be required. Only when a Remote requires more
bandwidth than is available in STDMA will a switch occur.
In Dynamic Cycle mode, each Remote will always appear to be running at near
100% capacity, even when there is actually excess bandwidth available. This is
because in Dynamic Cycle mode, the Remotes are almost never given more
bandwidth than they need. As a result, the algorithm for this mode uses a maxi-
mum allowed slot size rather than the actual allocated slot size to calculate the
effective data rate. This results in a more accurate estimate of the available
STDMA bandwidth.
Load Switching by a Remote
Once a Remote has been switched from STDMA mode to SCPC mode, it
checks its bandwidth requirements once per second to see if a change is needed.
The menu for controlling the Step Up/Step Down switches are set in the menu
shown in figure B-2.
Figure B-2 Auto Switching menu (Remote)
• Auto Switching - Same as for Hub.
• Load Switching - Same as for Hub.
• SCPC Step Up Threshold - Same as STDMA Slot Capacity at Hub.
• SCPC Step Down Threshold - Similar to STDMA Slot Capacity at Hub,
except Step Down is used to trigger a switch if the average load falls
below this value.
• SCPC Step Delay - Same as STDMA Switch Delay at Hub.