by Darius Kazemi, July 29 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.

Fractions are bad

RFC-210 is titled “Improvement of Flow Control” and is authored by William Conrad of Harvard. It's dated August 16th, 1971.

The technical content

This RFC concerns the way memory allocation commands work over the Host-Host Protocol. In particular, if host A asks host B to free up X amount of memory, host B frees that up and replies with “I have freed up X amount of memory”. The author suggest that the reply instead say, “I have freed up X amount of memory and you have Y amount of total memory to work with”.

He also recommends that a request to free up memory be unable to be repeated until a reply is heard back from the other site, and reply shouldn't be sent until the other site has met all its obligations on the network in terms of memory allocation (incoming data messages, essentially).

He also says that the way the command to free up memory is issued uses a different numerical format (fractional!) from the other memory commands (absolute), and it would make sense to make all of them represent memory in the same format.


The command in question is “give back”, known by its GVB moniker. This command is also the source of the issues that RFC-132 and RFC-154 are arguing about. In particular it's the fractional representations that are causing strife. Personally I think this author is correct and the fractions should be eliminated entire since they are clearly confusing people!

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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.