Network Hardware

The lowest level requirement of a network is the ability to send signals between neighbours on the network. A number of different media and technologies are used, some of the more important of which are:-

• Twisted pair or coax cable - typically used for short range (within one site).

• Land lines - e.g. leased lines from commercial telecommunication companies such as British Telecom, for long range.

• Fibre optics - used for very fast short range or fast long range.

• Satellite links - used for long range.

Each computer that forms part of the network is called a network node. In a network there is not always a direct connection between every possible pair of nodes so then communication between them has to go via intermediate nodes. For a number of political, economic and technical reasons there is not just one network to which all networked computers belong. The most important networks to us at Oxford are:-

Internet

Now the generic name for the global network. Originally the nodes were UNIX machines but all machine types can connect to it.

JANET

(also known as Super JANET) Joint Academic Network. Connects computers in universities and research centres within the UK. Includes the European research centres CERN and DESY. The backbone runs at 10G Bit/sec and Oxford connect via a line running at 2.5 GBit/sec. These number applied at the time of writing, but increase regularly.