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[ih] Origin of the loopback interface

On 21 Oct 2017 at 8:09, Dave Walden wrote:

> Bob Kahn was our modem expert and knew what the (Bell 303?) modem could
> do.? See
>  ?? http://www.walden-family.com/impcode/bbn-report-1877.pdf
> and search for "loop test".?? While this is a 1973 revision of the 
> report, I believe this description was in the original version of the 
> report in 1969. My further memory is that such testing could be done 
> remotely under software control.

My memory, too.  On the a line test, the IMP would loop its interface, 
loop its modem, and remotely loop the far-end modem back at it.  This 
allowed it to figure out if a line outage was either the modem crapping 
out, the line being broken, or the remote IMP being down.

Bernie Cosell                     Fantasy Farm Fibers
mailto:bernie at fantasyfarm.com     Pearisburg, VA
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