Comtech EF Data MIDAS 4 System and Design - Manual (Page 55)

System and Design Manual, Revision 2
Theory of Operation 3–13
The circuit termination initiated by the traffic node where both the traffic
nodes have dedicated Node Control Modems proceeds as follows:
1. The Node Control Modem disables the traffic modem transmits and
receives and sends a “path terminated” message to the NMS.
2. The MIDAS Controller responds by sending a terminate message to the
other Node Control Modem.
3. On receiving the terminate message, the other Node Control Modem
disables the traffic modem’s transmit and receive, and acknowledges the
terminate message.
4. On receiving the acknowledgment to the terminate message, the MIDAS
Controller releases the bandwidth and the traffic modems.
The sequence is illustrated in Figure 3-3.
NODE A NMS NODE B
TERMINATE
TERMINATE ACK
TURN OFF TRAFFIC
MODEM TRANSMIT
AND RECEIVE
PATH TERMINATED
TERMINATION
REQUEST THROUGH
USER PORT, RTS/DTR
GOING INACTIVE,
LOSS OF LOCK, CALL
DURATION EXPIRES
BANDWIDTH AND
TRAFFIC MODEMS
RELEASED
TURN OFF TRAFFIC
MODEM TRANSMIT
AND RECEIVE
Figure 3-3. Node Initiated Circuit Termination