Web standard has been stable since 1970
What is it?
TCP/IP is the universal network standard for the internet and internetworking in general. From the outset it was designed for establishing and managing connections between networks rather than devices.
Back in the 1970s, the team that created it were clear about its purpose, “Internetwork communication should be viewed as having two components: the hop-by-hop relaying of a message, and the end-to-end control of the conversation.”
Although the two most important protocols are the ones from which it takes its name (Transmission Control Protocol and Internet Protocol), TCP/IP is actually a suite of many different protocols, some of which, like FTP and HTTP, are familiar in other contexts. TCP/IP is intended to be as unobtrusive as possible to end-users.
Where did it originate?
TCP/IP came out of a US Department of Defense project to ensure military communications would continue after a nuclear attack by making use of any remaining networking capacity.
The Department of Defense sponsored Stanford University and the protocol’s creators to develop the suite. TCP/IP first became a military standard before entering the public domain with BSD Unix.
For practical purposes, TCP/IP started with version 4 - still the most widespread. For a more detailed history, see:
What is it for?
IP corresponds to Layer 3 of the OSI networking model, which handles addressing, delivery, fragmentation and reassembly. TCP (at Layer 4, the transport layer) manages connections between devices.
Each device is assigned a unique address and, because TCP/IP works at the mid-to-upper levels of the OSI model, the characteristics of the underlying network do not matter.
Although the devolved and democratic nature of the internet might suggest a peer-to-peer way of working, TCP/IP services use a client/server model in which hosts provide data in response to requests from clients such as web browsers.
What makes it special?
TCP/IP uses entirely open and non-proprietary standards and can operate on and interconnect any kind of network technology, public or private, Lan, Wan or wireless.
It is also massively scalable. Although the standards have been progressively refined, the technology that supports the tens of millions of internet connections in use today is essentially the same as that developed in the 1970s.
How difficult is it to master?
Leaving out one-day introductions, practical training in the basics of TCP/IP takes three to four days and usually demands existing experience of networks.
Where is it used?
In data and, increasingly, voice networking.
What systems does it run on?
Almost every local, wide-area and wireless network, regardless of supplier.
Not many people know that…
Appropriately for a technology that recognises no national or proprietary boundaries, TCP/IP is described as “stateless”. The path taken by any message is unrelated to that taken by any other communication between the same two devices.
What is coming up?
IP version 6, not yet widely accepted but described by its champions as “the future of the internet”.
Rates of pay
Salaries for people with TCP/IP skills vary widely as it is used in a wide range of roles from support and administration to network design and engineering.
TCP/IP training is available from networking equipment suppliers and independent trainers. Much of the free tutorial material on the web is old but still valid. One of the most complete and up-to-date is at
For a more heavyweight technical guide, you can download a 900-page Redbook from IBM