What is loopback test?
A loopback test is the process of sending digital data streams from a source back to the same point with no intended changes. It is generally run to determine if a device is working properly and if there are any bad nodes on a network.
Loopback testing is a diagnostic technique in which a signal is transmitted and returned to the same sending device after it has passed through all or part of a network to test the transport or transport infrastructure. A comparison of the returned signal with the transmitted signal shows the integrity of the transmission path. A loop plug, known as a sheath plug, is inserted into the port of a communication device to facilitate the loop back test.
Loopback tests are easily used to test computer serial ports and radio interfaces, and are one of the easiest ways to check RS-232 communications.
Interfaces such as aggregated ethernet, gigabit ethernet, fast ethernet, etc. can also be configured to run a loopback test to verify the connectivity of the links. The loopback test isolates circuit segments so that they can be tested separately.