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CDM-740 Advanced Satellite Modem
1:1 Redundancy
C.2
Introduction
Figure C-2 shows the block diagram for a 1:1 redundancy configuration for L-Band simplex or
L-Band full duplex operation. using a CDM-740 modem pair with a CRS-175L switch.
Figure C-2. CRS-175L – 1:1 Redundancy (L-Band Simplex or Full Duplex Operation)
The CRS-175L switch supports 1:1 redundancy in the following manner:
•
In normal operation, the primary and backup modems share all configuration parameters.
Changes to the primary modem (the online modem) are automatically transferred to the
backup modem. Any change to the backup modem is overwritten by the CRS-175L and
reverts to whatever configuration the primary modem is set to.
Additionally, the GE1 and GE2 Gigabit Ethernet data interface data ports are functional
on the primary modem and disabled on the backup modem, while the FE (10/100)
management port remains operational on both the primary and backup modems.
•
When a major alarm occurs in the primary modem:
o The primary modem's carrier is muted; however, BUC power, LNB power, and
o Rx signals are always routed to both the online and backup modems at all times.
1
BUC, LNB and 10MHz Reference functionality are optional features that may or may not be
enabled
1
10MHz reference
continue to be sent to the CRS-175L. The CRS-175L will
terminate the BUC power, LNB power, and 10 MHz internally and these signals
are then taken from the backup modem along with the backup modem's Tx
carrier.
C–2
Revision 0
MN-CDM740
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