Thats what you need to do, its your assignment, you wont learn if someone else does it for you..
[SIZE=-1]A high-speed line (or a series of connections) that forms a major pathway within a network.
www.verio.com/support/files/glossary.cfm
[/SIZE][SIZE=-1]The primary connectivity mechanism of a hierarchical distributed system. All systems which have connectivity to an intermediate system on the backbone are assured of connectivity to each other. This does not prevent systems from setting up private arrangements with each other to bypass the backbone for reasons of cost, performance, or security.
largebande.gc.ca/pub/technologies/bbdictionary.html
[/SIZE][SIZE=-1]the underlying network communication conduit or line by which all main servers and devices are connected; backbone devices are typically servers, routers, hubs, and bridges; client computers are not connected directly to the backbone.
www.sunrise.uk.com/glossary.html
[/SIZE][SIZE=-1]The top level of a hierarchical network. The main pipes along which data is transferred. The "Internet backbone" is sometimes referred to, though it doesn't exist.
www.netdictionary.com/b.html
[/SIZE][SIZE=-1]In a network, a backbone is a larger transmission path into which smaller lines feed. At the enterprise level, a backbone is a line or set of lines that local area networks connect to for a wide area network connection or within a local area network to span distances efficiently (for example, between buildings).
www.sidetrips.com/support/glossary_a_l.asp
[/SIZE][SIZE=-1]the part of a network that connects other networks together; "the backbone is the part of a communication network that carries the heaviest traffic"
wordnet.princeton.edu/perl/webwn[/SIZE]