Comtech EF Data CDD-880, Installation And Operation Manual

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CDD-880 Multi Receiver Router MN-CDD880
Appendix F Revision 2
F–3
for rapid deployment of units at the remote site and their addition to the VMS database at
the hub site.
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The network provides a true single hop solution for point-to-point or point-to-multipoint
connectivity between remote sites. VMS automatically sets up the circuits either by Type of
Service (ToS) detection through the remote site CDM-840, or a Distribution List configured
in the VMS server with the respective remote site policies.
Figure F-2. VMS-configured Advanced VSAT Network
Startup of an application such as VoIP or videoconferencing initiates a switch request using ToS
Detection. Upon ToS protocol detection, the CDM-840 forwards a switch request defined by
network operator switching policy to VMS for the required bandwidth. VMS in turn, upon
verification of available space segment and CDD-880 Expansion Demodulators, sends switching
commands to the appropriate remote CDM-840 subnets, thus changing the CDM-840’s Tx
frequency/power level/data rate and a varying assortment of modulation and coding
combinations called MODCODs, where applicable.
An available remote site CDD-880 is also tuned to receive the corresponding remote
transmission, and a mesh circuit is created. As with Remote Sites ‘A’ and ‘B’, Remote Site ‘N’ is
communicating with the Hub site via the CDD-880 Expansion Unit on another internal
demodulator port. Since the CDD-880 Expansion Units at Remote Sites ‘A’ and ‘B’ also have a
demodulator port tuned to their respective carrier, it is necessary to filter the traffic between
them at the Hub site to avoid duplicate packets and unnecessary hub loading. This requires the
entry of filter routes only at the hub’s CDD-880 Expansion Unit. VMS automatically manages
these routes – entering them when needed, and removing them when not.
From the VMS server interface, the Distribution List feature allows the operator to pre-define
mesh circuits based on an Entry Channel Mode (ECM) switch, multicast transmission from
remotes to a group of remotes, or the setup of monitor remotes. When the remote terminals