History of 127/8 as localhost/loopback addresses (2021)

Re:History of 127/8 as localhost/loopback addresses (2021) by imgabe on Wednesday May 25, 2022 @07:34AM (#31503057)

Coincidentally, I'm reading Where Wizards Stay Up Late about the development of ARPANet and it says:

> In designing the IMPs, BBN made it possible to loop the host and modem interfaces of the machine, so they could conduct “loopback” tests. The loopback test, which could be performed remotely, connected an IMP’s output to its input, effectively isolating the IMP from the rest of the network. This generated test traffic through the interface and allowed BBN to check the returning traffic against the outgoing traffic generated by the IMP.

So it seems like it was in there from the very beginning. No mention of the 127/8 address specifically though.

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Re:History of 127/8 as localhost/loopback addresses (2021) by Klaster_1 on Wednesday May 25, 2022 @08:31AM (#31503589)

Great book, read it after a recommendation here. Even though I studied telecoms, the networking origins were still very hazy, knowing how everything started changes the perspective. As a software developer, I can even relate to some aspects of the effort.

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Re:History of 127/8 as localhost/loopback addresses (2021) by zrail on Wednesday May 25, 2022 @08:34AM (#31503627)

The IMPs used an internal protocol that IP rode on top of. Like today, lots of networks use Ethernet at the physical layer today.

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