During the summer of 1981, Jon Postel worked at the University of Southern California's Information Sciences Institute (USC/ISI) to finalize the core architectural documents of the modern Internet. As the long-standing editor of the Request for Comments (RFC) series, Postel meticulously edited and formatted RFC 791, defining the Internet Protocol (IP), and RFC 793, defining the Transmission Control Protocol (TCP). Published in September 1981, these two documents formally codified TCP/IP version 4.
RFC 791 established the 32-bit addressing scheme, packet structure, and stateless packet-forwarding mechanism that allowed data to route across disparate physical networks. Simultaneously, RFC 793 defined the connection-oriented transport layer, providing reliable sequence management, flow control, and error recovery over the unpredictable IP layer. Together, they established the fundamental separation between transport and network layers, allowing applications to communicate without needing awareness of underlying hardware.
The publication of RFC 791 and 793 provided the definitive technical foundation required for vendor implementations and network migration. Over four decades later, IPv4 and TCP remain core pillars of global internet routing, illustrating the durability and foresight embedded in Postel's editorial work and the underlying engineering choices.
Why it matters
RFC 791 and RFC 793 established the definitive rules for IPv4 and TCP, forming the core operational blueprint of the Internet. By separating routing responsibilities (IP) from end-to-end connection management (TCP), this architecture enabled unprecedented flexibility and scalability. These standards allowed vastly different computer systems to communicate seamlessly and laid the technical groundwork for the Internet's explosive global growth over subsequent decades.
Interesting fact
RFC 793 contains the original formulation of the Robustness Principle, often called Postel's Law: 'Be conservative in what you do, be liberal in what you accept from others.'
People
- Jon PostelRFC Editor and Computer Scientist at USC/ISI
- Vint CerfCo-designer of TCP/IP
- Robert KahnCo-designer of TCP/IP
Quotes
"An implementation must be conservative in its send behavior, and liberal in its receive behavior."
Location
USC Information Sciences Institute · Marina del Rey · United States
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