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What is it?
TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communications protocol for the Internet. TCP/IP is now universal, bolted onto every operating system on every kind of computer.
Where did it originate?
TCP and IP are two elements of the Internet Protocol suite that originated with the US Defense Advanced Research Projects Agency (Darpa) in the 1970s. Darpa sponsored Stanford University and Bolt, Beranek and Newman (BBN) to develop the suite. TCP/IP entered the public domain when it was included in Berkeley Software Distribution Unix.
What is it for?
TCP breaks down the content of a message into small packets. IP handles the addressing, making sure the packets reach the correct destination. At the destination, TCP verifies that the packets are complete and intact and assembles them in the right order.
What makes it special?
TCP/IP enables any computer to communicate with any other. IP is packet-switched, in contrast to the circuit-switched technology traditionally used by telephone companies. Circuit-switched traffic travels over a predefined path which is reserved for the duration of the call. Packet-switched traffic is switched dynamically, finding its own way by using information in the packet header.
Telephone companies have invested billions of pounds in circuit-switched networks. But where circuit-switched price/performance doubles every four to five years, for IP networks it doubles every 18 months.
Operating costs are lower for IP, since it is a single network, with one set of management requirements for both voice and data. Also, by installing IP networks, telcos can set up new services such as Web-enabled call centres, unified messaging and other voice and data integration applications, which can be done in other ways but are easier and cheaper on IP.
How difficult is it?
Tens of millions of people use it every day without a moment's training. However, data network engineers and managers face a challenge when voice and data are converged on a single IP network.
Standards of uptime that data network users tolerate are not acceptable for voice traffic, and there are other issues to be managed, such as quality of service, guaranteed bandwidth, latency and jitter.
Where is it used?
In local area networks, wide area networks and increasingly in telecoms networks.
Not to be confused with . . .
A popular antiseptic mouthwash.
What does it run on?
It runs over Ethernet, Token Ring, Fibre Distributed Data Interface, Asynchronous Transfer Mode, X.25, Microsoft and Novell networks - in fact, any local or wide area network.
Few people know that
The race to put man on the moon gave us Teflon. The Cold War gave us the Internet. Darpa wanted to create a communications system that offered so many alternative routes that it could not be taken out by a single act of war, as is the case with a fixed network. TCP/IP is described as "stateless" because the path taken by any request or message is unrelated to that taken by any previous message between the same two computers.
What's coming up?
IP version 6, the "next-generation Internet Protocol".
In addition, the Internet Engineering Task Force has set up a working group for the use of the Internet in emergencies, such as terrorist attacks.
Rates of pay
TCP/IP network administrators can expect between £25,000 and £35,000, while network engineers and designers command between £30,000 and £50,000.
Independent TCP/IP training providers include Tech Connect ( www.tech-connect.com) and Erion ( www.erion.co.uk). Training is also available from suppliers such as Microsoft and Cisco and their partners.