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The graphics for this web site were created on a Macintosh computer, the text was written on a Windows Machine, you have downloaded this from a Windows 2000 server and are reading it on whatever machine and operating system you chose to buy. How is this possible? Enter TCP/IP

If you are involved with computers at all, then you will have probably come across TCP/IP. Look in your computers 'Network' settings and you'll see entries like this:

TCP/IP is a standard protocol (set of rules) which allows computers and other network devices to communicate with each other. It forms the basis of the internet and all the clever stuff that the web can do like browsing and sending mail, is all down to TCP/IP. The protocol itself is not owned by anybody, but is maintained by a network of volunteer groups which research, maintain and improve the protocol. The fact that it is public means that each vendor can ensure their products adhere to a standard.

There are many types of network protocol such as NETBUI, IPX/SPX, AppleTalk and on and on, but TCP/IP is universal like Esperanto! (just kidding)

TCP/IP stands for Transmission Control Protocol / Internet Protocol - quite a mouthful, hence the abbreviation. TCP/IP became standard issue when the US Government dictated that all computers using ARPANET (a forerunner to the Internet) should use TCP/IP as the networking standard. TCP/IP is a suite of protocols, applications and services designed to connect computers and networks with the following aims:

Independent of network model or design - it doesn't matter if a peer to peer network is being used with a Token ring or a Client server network over Ethernet, the system still works.
Over any transmission model - There is more than one way to physically connect computers such as cable, RF, and satellite.
Hardware vendor independent - It matters not whether computers are manufactured by Dell, IBM or Cobalt - TCP/IP will still work.
Operating system independent - Whatever Operating system you use, as long as it has a TCP/IP pack installed, you can communicate with other computers.

Nearly every operating system now has some sort of TCP/IP support built into it and this includes Windows, MacOS and Redhat. Traditionally TCP/IP was associated with UNIX as BSD (the Berkley distribution of UNIX) was the first operating system to ship with TCP/IP.

To describe a cheesy analogue for TCP/IP: If a computer network or internet was a road system and the cars were the data on the network, then TCP/IP would be the traffic lights, Highway Code, Traffic Police, Cones, Traffic Reports on the radio, and just about everything else.

TCP/IP is defined as a 5 layer model, which from the top down goes like this:

Application Layer - This is where all the high end activity such as mail sending and transferring files takes place
Transport Layer - When the packets are sent out across the network, the transport layer ensures that they can be reassembled in the right order
Internet Layer - Deals with the addressing and routing aspects of the transactions
Data Link Layer - Concerned with hardware and splits the data into packets
Physical Layer - Concerned with the hardware of the network such as cables and cards

The many protocols, applications and services included in the TCP/IP suite fit into some or one of these layers. TCP/IP is much more than just TCP and IP.

What's in the TCP/IP pack?

IP (Internet Protocol)

Internet protocol takes care of addressing on a TCP/IP network, it is the method by which packets know where to be delivered. IP numbers are discussed further here.

TCP (Transmission Control Protocol)

TCP as well as being an antiseptic fluid for cuts and bruises, helps ensure that all the data packets arrive safely. As the larger data chunks are broken into the discrete packets on the way out, they need to be counted back in on arrival. As well as just checking the numbers of packets, TCP takes care of ensuring that they are put back together in the right way.

UDP (User Datagram Protocol)

UDP performs a similar task to TCP but without the error checking and the packet re-assembly. UDP is described as 'connectionless' as it operates on a fire and forget basis. NFS, DNS and RPC use UDP for many tasks.

ICMP (Internet Control Message Protocol)

ICMP is mainly concerned with navigation round the network, the route from point A to point B may not always be the same depending on network conditions, the state of routers and so on. The most public face of ICMP is the PING command:

You can ping for yourself by typing at a DOS prompt:

PING www.yourname.co.uk

If you want the actual route that your computer takes to get to the web server which contains this site then type:

TRACERT www.yourname.co.uk

FTP (File Transfer Protocol)

Anybody that ever made a website knows what FTP does, its function is to transfer data from one device to another. Even FrontPage users use FTP, but they may not realise because it is all wrapped up in FrontPage extensions. FTP is discussed further in the FTP page.

SMTP (Simple Mail Transport Protocol)

This protocol transfers email messages from device to device. Its called Simple but when presented with the latest edition of Outlook, it may seem complex, but the protocol is all wrapped up in there somewhere. For more information on SMTP and Email issues click here.

NNTP (Network News Transfer Protocol)

This protocol is designed to provide the speedy transfer of news between servers and clients, if you've never heard of it go to Outlook Express and you'll see it in your accounts window:

DHCP (Dynamic Host Configuration Protocol)

When we get to the IP numbers page you will see that there are not enough IP numbers in the world for each device to have a unique identifier. The solution is DHCP, this protocol allows devices to be allocated an identifier when they join a network, be it an office network or the internet. DHCP is discussed further on the DHCP page, as it has quite a significant bearing on ADSL and Broadband.

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