RFC 2556

RFC 2556: OSI connectionless transport services on top of UDP Applicability Statement for Historic Status 💖

okay bestie, here's the title block tea ☕✨

• Author: Scott Bradner, Harvard University 🎓
• Category: Informational 📚
• Date: March 1999 🗓️
• Obsoletes / Updates: the header doesn't list either one 🤷‍♀️

---

Status of This Memo 🦋

this memo is just giving info to the Internet community 🌐. it does not specify an Internet standard of any kind, and distribution is totally unlimited 💅.

Copyright Notice 🎀

Copyright (C) The Internet Society (1999). All Rights Reserved. 💜

Abstract 🌸

so RFC 1240, "OSI connectionless transport services on top of UDP," got published as a Proposed Standard in June 1991 😭. but right now there don't seem to be any implementations that actually follow RFC 1240 💀. on top of that, people are getting pretty worried about using UDP-based transport protocols in places where congestion could happen 🌧️.

1. Use of RFC 1240 Technology 🍓

in October 1998 someone sent a message to the IETF list asking if anyone knew about real-world use of the tech in RFC 1240 👀. a bunch of people replied, including the International Organization for Standardization (ISO), which is basically the keeper of the OSI protocols 👑. but none of the replies pointed to any current use 😬. most of the folks who made a recommendation said RFC 1240 should get moved to historic 🏛️.

2. Responsiveness to Congestion 🚦

ngl, the Internet has learned SO much about congestion since 1991 📈. congestion control algorithms have gotten way better, but people are still working on understanding all the issues 🧠. in this environment, any UDP-based protocol is kinda sus 😰, because people who use UDP-based protocols often invent their own reliability and congestion control stuff 🛠️. that stuff might not include the current state of the art 📉. this leads to a danger of congestion collapse, which can have seriously bad consequences for the network it runs in 🚨. see RFC 896 if you want the deets on congestion collapse 📖.

for RFC 1240, the authors seemed to assume that if you needed some level of reliability, the reliability and congestion control algorithms you'd then need would just live inside the OSI protocols running over UDP 🤔. it's honestly not clear that the perks of running over UDP would outweigh the struggles of trying to build a reasonable congestion control algorithm 😩. implementers would probably find that running over TCP, the way RFC 2126 describes, is the better choice 💖.

3. Conclusion 💅

since nobody's using the tech from RFC 1240, and congestion control is a whole thing on the Internet right now, RFC 1240 should be reclassified as Historic 🏺, and its implementation should be actively discouraged 🙅‍♀️. no cap, that's the move 🔥.

4. Security Considerations 🔐

this type of non-protocol document does not directly effect the security of the Internet. ⚠️

5. References 📚

RFC 896   Nagle, J., "Congestion control in IP/TCP internetworks",
          RFC 896, January 1984.

RFC 1240  Shue, C., Haggerty, W. and K. Dobbins, "OSI connectionless
          transport services on top of UDP: Version 1.", RFC 1240
          June 1991.

RFC 2126  Pouffary, Y. and A. Young, "ISO Transport Service on top of
          TCP (ITOT)", RFC 2126, March 1997.

6. Author's Address 🏫

Scott Bradner
Harvard University
1350 Mass Ave, rm 876
Cambridge, MA
02138
USA

Phone: +1 617 495 3864
EMail: sob@harvard.edu

7. Full Copyright Statement 🌈

Copyright (C) The Internet Society (1999). All Rights Reserved. 💜

this document and translations of it can be copied and handed out to others 📄. derivative works that comment on or explain it, or help with implementing it, can be made, copied, published, and distributed, in whole or in part, with no restrictions at all 🎉. the only ask is that the above copyright notice and this paragraph stay on every copy and derivative work 🫶.

however, the document itself may not be modified in any way, like removing the copyright notice or the references to the Internet Society or other Internet organizations 🙅‍♀️. the exceptions are when you need it to develop Internet standards (then you follow the copyright procedures in the Internet Standards process) or when you need to translate it into languages other than English 🌍.

the permissions above are perpetual and won't be revoked by the Internet Society or its successors or assigns ♾️✨.

this document and the information in it are provided on an "AS IS" basis, and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 🫠