to test a network cable
the function of loopback to connect to tcp/ip in networking
(config)#no interface loopback x
The only difference is the relative location of the device that is in loopback mode. Local loopback testing is when your device is set to send back everything it receives to the sender, aka loopback mode. Remote loopback testing is when your device orders a foreign device to enter loopback mode.
It's a USB loopback connector.
127
In IPv4, the loopback address is 127.0.0.1. In IPv6 it is ::1.
The loopback address for each machine is 127.0.0.1, regardless of how many machines are on the network.
You would use a Loopback Plug, this allow an output signal to be returned as input.
127.0.0.1
127.0.0.1 is the loopback address in IP.... or in the (slightly modified) words of Dorthy Gale when she returned from Oz "There's no place like 127.0.0.1"
Loopback address