Automatic Switching; General; Bandwidth Allocation And Load Switching - Comtech EF Data Vipersat CDM-570 User Manual

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UTOMATIC

General

Automatic switching is a feature of VMS which allows dynamically changing
network configuration in response to changes in either traffic type (application
switching) or network traffic loads (load switching.)
The following discussions apply to the Vipersat CDM-570/570L, CDD-564L,
and CDM-600. Throughout the following discussion, these units are referred to
as modem/routers.

Bandwidth Allocation and Load Switching

Load Switching is the mechanism by which the Vipersat network switches a
remote terminal from STDMA to SCPC mode based on traffic levels at the
remote. There are two components of load switching in a Vipersat system: VMS
(network management) and CDM (Comtech Data Modem). The VMS compo-
nent receives switch requests from the CDM, and based on policy settings and
available resources, either grants or denies the request. Within the CDM compo-
nent, load switching is managed at either the Hub or the Remote, based on the
current mode of operation. When a remote is in STDMA mode, load switching
for that remote is managed by the Hub STDMA controller. After a Remote has
been switched to SCPC mode it manages its own switching (or Step Up / Step
Down) requests.
The basic concept for all load switching is that a running average of current
utilization is maintained, and when that utilization exceeds a pre-set threshold, a
switch is initiated. The data rate for the switch is computed by determining the
current bandwidth requirement of the remote and adding some percentage of
A p p e n d i x A u t o m a t i c S w i t c hi n g
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WITCHING
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P P E N D I X
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