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[ih] Origin of the loopback interface

On 10/20/17 11:44 PM, Jack Haverty wrote:

> IIRC, loopback was a term used in modems at least as early as the late
> 60s.  Maybe before.  When a line was put "in loopback" all the data
> going out onto the line was reflected directly back to the sender.
> ....
> So, the specific term "loopback interface" probably depends on the
> context.  It may have been first used in Unix, but the concept of
> "looping an interface" was much older.  It existed in modems, and in the
> ARPANET, and in the Internet, and was used primarily for debugging and
> fault isolation during operations.  When something works, you just keep
> using it.....
The term "loopback" goes all the way back to early electrical circuits - 
bridging two wires with a cliplead, at various points, to test connectivity.

Miles Fidelman

In theory, there is no difference between theory and practice.
In practice, there is.  .... Yogi Berra