Transcript Document
Networks & Communication #1 GCSE work • LAN Networks • WAN • Local Area Network • Wide Area Network LAN (1) LAN: Computers connected by cable Old networks used this layout called a BUS network. The cable physically ran from computer to computer. A server would just have been one machine connected to the cable. At each end of the cable was a “terminator”. Break the cable: all network traffic stops LAN We now use a tree layout for the network: Break a cable… and it stops one computer… or maybe one section of the network… LAN Terminology: • SWITCH – a device into which cables from a group of computers are connected. • Its function: to allow multiple computers to be grouped together and communicate with other switches/hubs/computers on the network. • It is “intelligent” as it learns which computer is connected to which port. • PORT – a physical connection on the switch. LAN Terminology: • HUB – a device into which cables from a group of computers are connected. • Its function: to allow multiple computers to be grouped together and communicate with other switches/hubs/computers on the network. • It is NOT “intelligent” so messages reach their destination by trial & error. LAN • Computers connected to a network require a NETWORK INTERFACE CARD or NIC for short fitted to them. LAN (2) LAN: Wireless network • We have added wireless networking to the school. • Wireless Access Points are distributed around the school to allow computers to connect to the main school network. • Why? Not everywhere is cabled. It gives laptop users the option of being connected to the network no matter where they are. LAN Wireless • The RANGE that wireless can work depends on the buildings and obstructions to signals. • One WAP is in the technology block and a signal can be picked up anywhere in that building. • It is possible to pick up a signal just in front of the trees near the art block… LAN Wireless • A Wireless Access Point • A Wireless Network Card LAN • So now our network diagram looks like this: WAN (3) WAN • An example of a Wide Area Network is the Internet. • Millions of computers around the world all able to communicate with each other, access web pages, Email and more. • To be part of a WAN, you need a phone line & modem. Some need satellites, ISDN or ADSL to be part of the network. WAN & BGS • Our network now looks like this: WAN Terminology: • ROUTER – a device to carry transmissions from one network (our LAN) to another network (Internet). • Why don’t we use a modem? It’s too slow. 56,000 bits per second for a modem v 2,000,000 bits per second for the router and the broadband (fast) connection we have. http://static.howstuffworks.com/flash/router-inet.swf Homework • • • • Go through this presentation again Learn the TERMINOLOGY Know what a LAN and WAN are Have a good reason why wireless networking can be an advantage to some computer users.