Loop (telecommunication)
|
|
A loop is a hardware or software device which feeds the incoming signal or data back to the sender. It is used to aid in debugging physical connection problems.
Local loop is a telecommunications term for the "last mile" connection from the trunk to the subscriber.
Many network devices can be configured to send specific patterns (such as all ones) on an interface, and can detect the reception of this signal on the same port. A circuit between two points in different locations may be tested by applying a loop on the circuit in one location, and having the network device at the other location send a signal through the circuit. If this device receives its own signal back, this proves that the circuit is functioning.
A hardware loop is a very simple device that hardwires receive to transmit. In the case of a network termination connector such as X.21, this is typically done by simply connecting the pins together in the connector. Media such as optical fiber or Coaxial cable, which have separate transmit and receive connectors, can simply be looped together with a single strand of the appropriate medium.
A modem can be configured to loop incoming signals from either the remote modem or the local terminal. This is referred to as a software loop.