A 1974 Design Still Rules the Internet. Why? The 6 Design Philosophies of TCP/IP

Sat, 18 Jul 2026 09:30:00 +0800

TL;DR

TCP/IP is almost 50 years old. Every one of its rivals — the phone companies’ X.25, IBM’s SNA, the standards body’s OSI — is in a museum, yet it still carries every page you load today. It didn’t win by being the most advanced. It won through six design choices:

Packet switching: no private trains — everyone shares the highway. Cheap, and hard to kill;

Layering: each layer does one job and can be swapped out like a LEGO brick;

The end-to-end principle: keep the network dumb and put the smarts at the edges — so innovation never requires rewiring the network;

Best effort: the core promises nothing, reliability is bought à la carte — simple scales globally;

Rough consensus and running code: no kings, no voting — standards grow by working, not by decree;

Room for the future: from IPv4 to IPv6, from HTTP/1 to HTTP/3 — the foundation stays while everything above is rebuilt.

One sentence: good design doesn’t predict the future; it leaves room for it. This is the companion piece to Why Is Your WiFi Lagging? — that article explained what the network is and how to use it; this one explains why it was designed this way and how it survived half a century. All screenshots come from real systems and real protocol documents; IPs and hostnames are masked.

IETF on Margrop Blog

A 1974 Design Still Rules the Internet. Why? The 6 Design Philosophies of TCP/IP