Comtech EF Data MIDAS 4 System and Design - Manual (Page 33)

System and Design Manual, Revision 2
Solutions 2–9
Figure 2-3. Automatic Circuit Restoral
The traffic modem is connected to the router’s backup port via a synchronous
serial interface. The Node Control Modem is configured with all the
information required for requesting a circuit to the pre-determined destination.
• When the traffic modem detects an active RTS/DTR signal from the
router indicating traffic is incoming.
• Node Control Modem is notified. The Node Control Modem sends a
request to the MIDAS Controller for the establishment of a backup
circuit.
• The router also can request the backup circuit establishment by
sending user port commands to the Node Control Modem.
The MIDAS Controller validates the request, allocates traffic circuit
frequencies, and informs the Node Control Modems. Upon receiving the
frequency assignment, the Node Control Modems tune the respective traffic
modems to the assigned frequencies and turn them on either to transmit or
receive, leading to a backup circuit establishment. The circuit remains active
until the router deactivates the RTS/DTR signal or sends a terminate command
through the user port, at which time it is terminated and the bandwidth