The Hegemony of TCP
There’s an interesting article in the Spectrum magazine about the history of open networking and how ultimately the open standards defined by ITU committees got overtaken by TCP/IP. We still sometimes talk about the 7-layer model ( a product of those committees), but in truth networking is now synonymous with TCP/IP, which has 2-layers ( network and transport ) with some various link layers below, and an application sat directly on top.
Many of the applications that were expensively developed in the OSI model (like X.400 for email and FTAM for file transfer) are eclipsed by their rather less rigorous TCP equivalents (e.g. SMTP/IMAP and FTP or HTTP ). The world’s international X.25 networks have closed down, and X.400 is now relegated to specialised public sector usage, having been long bumped from conventional implementations like Microsoft Exchange.
In some ways, the packet-switching adventure is now reaching its final victory. Part of the drive for OSI came from the need to use packet-switched networks to use network infrastructure more efficiently than the existing circuit-switched model could. Now, with developments like LTE we are looking for packet switching (UDP/IP) to implement the transport of voice all the way to the handset, even in wireless systems.
There’s a sense of rebelliousness and anarchy in the world of IP that has been good for creativity, and for creating large-scale systems that just work. It gives you hope just to look at it.