RFC 1149

Network Working Group                        D. Waitzman
Request for Comments:                            BBN STC
                                            1 April 1990

  A Standard for the Transmission of IP Datagrams on Avian Carriers

Status of this Memo

   This memo describes an experimental method for the encapsulation of IP datagrams in avian carriers. This specification is primarily useful in Metropolitan Area Networks. This is an experimental, not recommended standard. Distribution of this memo is unlimited.

Overview and Rational

   Avian carriers can provide high delay, low throughput, and low altitude service. The connection topology is limited to a single point-to-point path for each carrier, used with standard carriers, but many carriers can be used without significant interference with each other, outside of early spring. This is because of the 3D ether space available to the carriers, in contrast to the 1D ether used by IEEE802.3. The carriers have an intrinsic collision avoidance system, which increases availability. Unlike some network technologies, such as packet radio, communication is not limited to line-of-sight distance. Connection oriented service is available in some cities, usually based upon a central hub topology.

Frame Format

   The IP datagram is printed, on a small scroll of paper, in hexadecimal, with each octet separated by whitestuff and blackstuff. The scroll of paper is wrapped around one leg of the avian carrier. A band of duct tape is used to secure the datagram's edges. The bandwidth is limited to the leg length. The MTU is variable, and paradoxically, generally increases with increased carrier age. A typical MTU is 256 milligrams. Some datagram padding may be needed.

   Upon receipt, the duct tape is removed and the paper copy of the datagram is optically scanned into a electronically transmittable form.

Discussion

   Multiple types of service can be provided with a prioritized pecking order. An additional property is built-in worm detection and eradication. Because IP only guarantees best effort delivery, loss of a carrier can be tolerated. With time, the carriers are self-regenerating. While broadcasting is not specified, storms can cause data loss. There is persistent delivery retry, until the carrier drops. Audit trails are automatically generated, and can often be found on logs and cable trays.

Security Considerations

   Security is not generally a problem in normal operation, but special measures must be taken (such as data encryption) when avian carriers are used in a tactical environment.

Author's Address

   David Waitzman
   BN Systems and Technologies Corporation
   BBN Labs Division
   10 Moulton Street
   Cambridge, MA 02238

   Phone: (617) 873-4323

   EMail: dwaitzman@BBN.COM

Expanded in RFC 2549.

As of last Saturday, April 28, 2001, RFC 1149 should probably be marked as "proven" or something to that effect. (It's currently marked as "experimental", if I recall correctly.)

Although I'm not a member of the Bergen Linux User Group (BLUG), I was invited to participate by a friend of mine, and I take the liberty of copying the initial report / announcement from the event here:

---

Finally, rfc 1149 is implemented! On saturday 28th of april 2001, the worlds very first rfc 1149 network was tested. The weather was quite nice, despite being in one of the most rainy places in Norway.

The ping was started approximately at 12:15. We decided to do a 7 1/2 minute interval between the ping packets, that would leave a couple of packets unanswered, given ideal situations. Things didn't happen quite that way, though. It happened that the neighbour had a flock of pigeons flying. Our pigeons didn't want to go home at once, they wanted to fly with the other pigeons instead. And who can blame them, when the sun was finally shining after a couple of days?

But the instincts won at last, and after about an hour of fun, we could see a couple of pigeons breaking out of the flock and heading in the right direction. There was much cheering. Apparantly, it WAS our pigeons, because not long after, we got a report from the other site that the first pigeon was sitting on the roof.

And finally, the first return pigeon arrived. The packet was carefully removed from the leg, unrolled and scanned. After manually verifying the OCR and correcting the few mistakes (gocr is quite good, but it *did* have problems recognizing F's in my end), the packet was accepted as a valid packet, and there was much cheering about what we saw:
64 bytes from 10.0.3.1: icmp_seq=0 ttl=255 time=6165731.1 ms

The remaining pigeons arrived simultaneously. Two of them didn't have any IP packets, though, it turned out that things had been so busy at the other end that they forgot to shut the pigeon cage, and the remaining two pigeons escaped without an IP packet. There was only six return pigeons, thus we got four ping replys, with ping times varying from 3211 to 6389 seconds. I guess this is a new record for ping times...

The implementation was declared a success. Now, we're waiting for someone to write other implementations, so that we can do interoperability tests, and maybe we finally can get the RFC into the standards track...

---

The official pages relating to the event can be found at

• http://www.blug.linux.no/rfc1149/

and there are mirrors at

• http://www.pvv.org/rfc1149/
• http://vidar.gimp.org/rfc1149/

From Programming Pearls, Second Edition by Jon Bentley.
ISBN 0-201-65788-0.

In the early 1980's Lockheed engineers transmitted daily a dozen drawings from a Computer Aided Design (CAD) system in their Sunnyvale, California, plant to a test station in Santa Cruz.
Although the facilities were just 25 miles apart, an automobile courier service took over an hour (due to traffic jams and mountain roads) and cost a hundred dollars per day.
Propose alternative data transmission schemes and estimate their cost.

The computers at the two facilities were linked by microwave, but printing the drawings at the test base would have required a printer that was very expensive at the time. The team therefore drew the pictures at the main plant, photographed them, and sent 35mm film to the test station by carrier pigeon, where it was enlarged and printed photographically. The pigeon's 45-minute flight took half the time of the car, and cost only a few dollars per day.
During the 16 months of the project the pigeons transmitted several hundred rolls of film, and only two were lost (hawks inhabit the area; no classified data was carried).

Because of the low price of modern printers, a current solution to the problem would probably use the microwave link.

Your radical ideas about radical ideas have already occured to others.