Semi-automatic circuit restoral – Comtech EF Data MIDAS 4 System and Design User Manual
Page 34
System and Design Manual, Revision 2
2–10 Solutions
released. Since the circuit is only activated on demand, satellite resources are
not used until needed.
Hunt Groups
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can be used to provide many-to-many (m x n) mapping of the
backup circuits, allowing for backing up more circuits using fewer modems.
They can also be used to provide redundancy for the data modems. Additional
modems are employed at the destination and configured as a hunt group. In
case of failure in one of the modems, the system selects another available
modem in that hunt group while establishing the backup circuit.
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Automatic circuit restoral depends upon the ability of the customer’s
equipment to generate a RTS/DTR (or similar control signal) transition when
the backup path is needed.
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If the customer equipment is unable to provide RTS/DTR or a similar
control signal to trigger the setup and termination of the backup
circuit, the user port commands can be used to request backup circuit
establishment and termination.
In case of primary link failure, the user requests the establishment of the
backup circuit through the user port. Once the primary circuit is restored, the
user can request termination of the backup circuit through the user port.
The circuit restoral time is comparable to the automatic operation, which
means the backup circuit is established within a few seconds of the user
entering the request through the user port. Comtech EF Data’s extensive line of
modems and interfaces are available for semi-automatic restoral, giving users
the maximum flexibility within the data rate range of 2.4 kbps to 100 Mbps.
1
A hunt group is a list of traffic channels that can span multiple nodes/sites.