Comtech EF Data CDD-56X Series Vipersat - Manual (Page 66)

Vipersat Configuration MN/22137, rev 1
3-32 Vipersat CDD-56X Series User Guide
parameters are operator selectable. The speed with which STDMA reacts to
changes in dynamic load is a function of the Statistics Accumulation Window
parameter and the Cycles per New Burst Map parameter, both of which are also
operator selectable.
The Hub statistics are useful for tuning the Burst Controller. Preamble adjust-
ments, up or down, are made using the missed ACKs statistic; a preamble and/
or guardband that is too short will result in an accumulation of missed ACKs.
The “Cont” column represents continuous—the number of sequential ACKs
missed.
An informative indicator in the Hub Statistics screen is the STDMA status of
the Remotes that appears in the first column to the right of the IP Address list.
The Remote status is displayed in one of three possible modes:
• E – Remote is Enabled and active in the STDMA group; the Hub burst
controller is receiving ACKs from this Remote.
• ER – Remote is Enabled but has been Removed from the STDMA group
due to missed ACKs at the Hub burst controller.
• (Blank) – Remote either has been manually Disabled, such as through the
STDMA Remotes Menu Enable/Disable command, or has been switched
out of STDMA to SCPC mode by the VMS.
STDMA/SCPC Automatic Switching
One of the most powerful features of the Vipersat Network system is the capa-
bility to perform Automatic switching between STDMA mode and SCPC mode
based on bandwidth demand. The configuration options that are available to
meet customer-specific requirements are extensive, and include switching based
on Load, Application (Voice and Video RTP), ToS, and QoS.
For additional information, refer to Appendix B, “Automatic Switching”, in this
document.
Note: Care must be taken when configuring the Auto Switching features of the
Vipersat system to ensure that there is no duplication or overlap of
switching functions between Application, ToS, and QoS for a particular
traffic flow. Only one of these switching methods should be utilized for
any one flow requirement.
Automatic Switching for the CDD-56X is an option that is available only when
configured as an STDMA Hub unit (burst controller). Note that Automatic
switching does not apply to either a Hub Expansion unit or a Remote Expansion
unit; these Vipersat working modes operate in dedicated SCPC mode and all
NOTE