|The Comtech CRS-500 1:N Modem Redundancy
System is intended for hub applications, and provides automatic or manual protection for up to 10 Traffic (or prime) modems with one redundant (or standby) modem.
The CRS-500 supports the CDM-625 and CDM-750 modems for select interfaces. The CDM-625 is supported when using the 10/100 Packet Processor mode. The CDM-750 is supported when using the G.703 interface or the Gig-E interface in all modes.
As shown in the figure, the CRS-500 is a flexible, modular-type architecture, composed of a Control Switch Unit (CSU), Data Switch Unit (DSU) and
optional IF Switch Units (ISUs).
A key feature of the CRS-500 architecture is its ability to allow the redundant modem to ‘bridge’ a traffic modem. The CRS-500 controller automatically configures the redundant modem to match the bridged traffic modem’s configuration. The CRS-500 also provides a copy of the bridged traffic modem’s TX traffic data to the redundant modem. When using the IF Switch Units (ISUs), it additionally routes the bridged traffic modem’s RX IF.
CRS-500 Control Switch Unit (CSU)
The CSU is the controller of the CRS-500 Redundancy System and consumes only 1RU of rack space. It contains field-replaceable modules such as the CRS-530 controller and dual, hot-swappable Power Supply Units (PSUs).The configuration of each traffic modem is stored in the CRS-530 controller. This information is used to program the redundant modem if a traffic modem fails. The CSU contains an extensive M&C system and is fully controllable from the front panel or from external 10/100 Ethernet or EIA-232C/485 ports located on the back side of the CSU unit, (on the CRS-530 module). Ethernet is used by the switch to communicate to all modems. A 10/100 Ethernet M&C connection goes to/from each modem to the CSU.