Comtech EF Data CDM-570/570L Vipersat - Manual (Page 119)

Appendix B - Automatic Switching B-1
A
P P E N D I X
A
UTOMATIC
S
WITCHING
General
Automatic switching is a feature of the VMS that allows dynamically changing
the network configuration in response to changes in either network traffic loads
(Load switching), traffic type (Application switching), or Type of Service (ToS
switching) detecting stamped packets with Diffserv values. Entry Channel
Mode switching is also covered.
These switching types are presented in the following material which uses CDM-
570/L, SLM-5650A, and Series800 modem units for purposes of illustration.
For simplicity, these units shall be referred to as modem/routers.
The basic signal topology in a Vipersat network is TDM (Time Division Multi-
plex) outbound and Vipersat’s proprietary STDMA (Selected Time Division
Multiple Access) inbound. The STDMA slots can have their duration and band-
width allotments varied, tailoring bandwidth allocation to meet the bursty traffic
load of a typical data network.
When required, a network is switched from STDMA to SCPC. SCPC band-
width is allocated from a bandwidth pool by the VMS to meet QoS or other
requirements for the duration of a connection. When the SCPC connection is no
longer required, the bandwidth is returned to the pool for use by another client.
This basic structure gives the VMS-controlled network its flexible, automated
network utilization and optimization capability.
The VMS has the intelligence to interpret the constantly changing statistics
gathered by the Vipersat modem/routers and uses this data to issue commands