Hughes HX System, System Overview

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Chapter 2 • Subsystems
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Return channel control processor
The return channel CP is a Pentium III single-board computer in
the cPCI chassis that manages the RCDs. Depending on the NOC
rack configuration, there may be 1, 2, or 4 CPs in a system.
Return channel IF distribution
The return channel IF distribution module receives the IF output
from the system IF distribution module and forwards it to the
RCDs.
Dynamic network control
cluster (DNCC)
The dynamic network control cluster (DNCC) performs all the
processing and control functions of the inroute subsystem. The
DNCC manages return channel bandwidth. The DNCC receives
traffic bursts and control bursts. The traffic bursts contain modem
IP traffic as well as “piggybacked” bandwidth requests. The
control bursts can contain modem status, bandwidth requests, or
ranging information. Ranging is used to adjust the operational
parameters of a site and to fine-tune the satellite router's timing
and transmit power without the need for user intervention. If the
DNCC requests that the satellite router enter ranging mode, the
satellite router uses its assigned ranging burst. Based upon these
measurements, the site chooses the proper settings to transmit
traffic to the DNCC.
The DNCC processes each type of burst and constructs IP
packets, which are forwarded to the IP gateways. Different
bandwidth allocation algorithms are implemented on the DNCC.
Additionally, the DNCC generates the frame timing messages and
forwards them to the timing components.
The DNCC is simple network management protocol
(SNMP)-enabled and is configured, controlled and monitored by
Vision UEM running on the NMSS.
The DNCC maintains detailed logs on all events pertaining to the
downlink subsystem. These include ranging/commissioning
information, inroute packet statistics, and other relevant data.
Redundant HX gateways contain two DNCCs configured as a
warm redundant pair with primary (online) and secondary
(standby) modes of operation.
Control Processor To maximize efficiency when processing traffic, each inroute
defined at the DNCC is assigned an inroute group. All inroutes in
the same group are managed by the same CP. The number of
inroutes differs between CDS and IFSS-TC (older systems).