A hard loopback test in telco speak is a simple device that connects the transmit tip side of a circuit to the receive tip side, and the transmit ring side to the receive ring side to complete a loop where the circuit is actually sending and receiving to itself. The device is usually an RJ45x plug that a tech will modify and place into a D-mark jack. By doing this, say in a T-1 circuit, you end up with a monitoring situation where the remote end tester can send and receive patterns to check whether a circuit is taking any errors. This can also be achieved by sending a loop pattern to a piece of equipment causing it to go into a loop for testing. But the hard loop is a physical piece placed into the circuit usually where the customer plugs his equipment. Mike Q Special Equipt Installer --GTE/Verizon 30 years
No reason. It is a post-test loop.
pre-test
Loop-Back
Loop-Back
A loop back plug.
A loop-back plug is a device used to test network equipment by sending signals back to the source. Common examples include a serial loop-back plug, which connects the transmit and receive pins on a serial port, and an Ethernet loop-back plug, which connects specific pins on an RJ45 connector to test network interfaces. These plugs are essential for diagnosing and troubleshooting connectivity issues in networking devices.
The while loop is a pre-condition loop. It tests the condition at the beginning of each loop, executes the loop if it is true, and goes back to the test after executing each iteration.
Loop-Back Plug
break
The test condition in a loop is what's used to determine when the loop should end.
A Loop-back plug.
The difference is that pre means before and post means after in Latin so it's tested before or after. :)