A Protocol is best described as a language understood by two operating systems and in the case of networking protocols the routers and bridges which make up the network.

There are three protocols you may come across they are:

IPX/SPX, the novell networking protocol. This is being phased out in favour of TCPIP.

NetBuei this was the Microsoft default protocol and yet again is being phased out.

TCPIP the current Champ and the protocol of choice for the internet. TCPIP addresses are currently made of four elements and look like 101.174.224.24, with each of the four segments having a range from 0 to 255, this allows about 6.4 Billion addresses on the internet

Mac addresses

Very few people will ever need to know the Mac, or physical address of their networked PC, however network administrators and the terminally curious may. The reasons are tied up with the way that some networks and most broadband providers issue IP (TCPIP) numbers to their users.

IP nos can be issued in two ways, either 'static' where your organisation ( a large corporation, or University) has a bank of IP nos and each is assigned to a specific PC by the system administrators, the IP no is kept on the machine. The alternative is DHCP, dynamically as each pc needs an IP no, it's given one from a list by the DHCP server. You may come across organisations that do both. DHCP is how broadband suppliers issue IP nos.

we will look at DHCP later in this section.

There are a number of programs out there which will tell you the Mac and IP nos of a machine, however within windows, or rather at the command prompt we have a utility called ipconfig which will show you a range of information about your network configuration. It will not however allow you to change anything!

To use ipconfig start a DOS session by ‘clicking’ on the Start button on the taskbar (usually at the bottom of the screen) and when the menu appears select ‘Run’. This will bring up a dialogue box , type cmd and select OK, or press the return key and a DOS (Command) window will open.

AT the C:\> prompt, which will look similar to the one shown, type ipconfig and hit the 'Enter' key.

Here we see the result of the ipconfig command. It shows the IP nos of a card.

Like many command level utilities ipconfig comes with switches that make it show specific details, in this case we'll use the /all switch as in ipconfig /all. As you can see you get a lot more detail now.

In case you haven't noticed the PC has two network cards, the first one, the 3Com TX card connects to my house LAN, the Gigabit card (inbuilt on my motherboard) runs my broadband connection. The IP nos on my house LAN I assigned myself. As there is no external connection on that network, the numbers are irrelevant, the '45' being my house number, the last '45' denoting this machine. Other PCs on my network have different last numbers to differentiate them. The details for The Gigabit (external) connection are defined by my ISP.

Here we see an Ubuntu Linux network settings dialogue box. Yet again it has two network cards, the card eth1 is connected to the house network, while eth0works the internet connection through the router.

The internet connection is made through the house router, the DNS IP no is the default IP for the netgear router and that's all it needed to get on the web

How data moves around the network

Data is not moved around the internet in one continuous stream, the data you receive is split into packets, just as the requests you sent were. If this were not the case then anyone connected to a webserver would 'hog' it, stopping other users connecting. Splitting the data into small pieces each of which may be destined for a different location provides a fairer solution.

A packet consists of three elements. The header which contains the address of the receiving machine. The data to be sent and a stop bit to indicate the end of the packet.