RFC 1149 (IP over Avian Carriers)

networkingops culture

An April Fools' RFC from 1990 that specifies carrying IP datagrams by homing pigeon.

RFC 1149 defines encoding datagrams on paper wrapped around a pigeon's leg, with a straight-faced discussion of packet loss and latency. In 2001 the Bergen Linux User Group actually implemented it, pinging a host across town with a measured loss of four packets in nine and multi-hour round-trip times.

RFC 1149, published on 1 April 1990, specifies the transmission of IP datagrams over avian carriers: printed on paper, rolled around a pigeon's leg, with packet loss described in terms of hawks and delivery times measured in hours. It is a joke, and it is written to specification standard throughout, which is what makes it work.

The joke has a technical point. IP was deliberately designed to be indifferent to the layer beneath it, so a specification for running it over pigeons is absurd and also entirely legitimate, since the protocol genuinely does not care. The document demonstrates layering by taking it to its logical extreme, which teaches the concept better than a straight explanation would.

It was then actually implemented. A Norwegian Linux user group carried out the experiment in 2001, achieving a handful of successful pings with round trip times in the range of one to two hours and substantial packet loss. The April Fools RFC tradition it belongs to includes several others of similar quality, and the series is a reminder that a field with a sense of humour about its own formality tends to be a healthier one.

Also known as: IP over Avian Carriers, pigeon protocol, avian carriers, CPIP

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