by Darius Kazemi, December 13 2019

In 2019 I'm reading one RFC a day in chronological order starting from the very first one. More on this project here. There is a table of contents for all my RFC posts.

Echo process

RFC-347 is titled “Echo Process”. It's authored by Jon Postel of UCLA and dated May 30, 1972.

The technical content

Postel suggests that all willing hosts implement a special type of process that a remote user can connect to. All it does is receive a message from you and then as quickly as possible send back the exact same message, unmodified. This would help with measuring delay on the network.


This RFC was submitted on the same day as RFC-346, Postel's thoughts on satellite connections. Presumably he was thinking about how one would measure satellite link delays and it occurred to him that this would be a useful debugging feature in general.

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About me

I'm Darius Kazemi. I'm an independent technologist and artist. I do a lot of work on the decentralized web with ActivityPub, including a Node.js reference implementation, an RSS-to-ActivityPub converter, and a fork of Mastodon, called Hometown. You can support my work via my Patreon.