1. Higher Computing Networking

2. Networking – Local Area Networks

3. ► Cover a small area such as a room or one building. ► A Network Interface Card (NIC) lets the computer communicate with the network. ► Each NIC has a Media Access Control address (48 bit). A unique number that identifies each computer on the network. ► Wireless NICs (WNIC) are used on a wireless LAN.

4. LAN – Transmission Media ► Have very high bandwidth i.e. 100 – 1000 Mbps. ► They frequently use (CAT5) copper cable. ► For very high bandwidth, fibre optic cables can be used. ► Wireless transmission media such as WiFi are becoming more common.

5. LANs Advantages ► Access to shared hardware such as printers. ► Access to shared software such as applications packages or anti virus. ► Provide communications facilities for network users such as internet and email. Disadvantages ► Network cards and cabling, costs can be high. ► A fault with a server can effect all workstations. ► Security procedures are needed to restrict access to user's files and to prevent the introduction of viruses.

6. LAN - Bus ► All computers communicate using a shared communications channel called the bus. ► Data from different computers can collide. ► In order to share this one cable, CSMA/CD is used. ► Relatively cheap and easy to install. ► Too many computers = increased collisions = reduced performance.

7. LAN - Star ► Each computer has its own communications channel. ► All data passes through a central computer, either a HUB or a SWITCH. ► A break in a communication channel only affects one computer. ► If the central computer fails, the whole network will not work – no communication. ► Uses CSMA/CD with a HUB.

8. LAN - Ring ► Like a BUS network, this has a shared communications channel but it forms a ring. ► If the communications channel fails, the whole network fails. ► Uses a system called token passing so many computers can share the one cable. ► can be expensive to set up.

9. LAN - Mesh ► Multiple connections between each computer. ► Offers protection against communications channel failure. ► Avoids bottlenecks as there are several paths. ► Expensive to set up.

10. Networking - HUB ► Used to connect nodes on a network. ► Data entering one port is sent out all of the other ports. ► All nodes on a network ‘hear’ a message even if its’ not for them. ► Can be used to connect LAN segments together to form a larger LAN.

11. Networking - Switch ► Unlike a HUB, this makes ‘point to point’ connections. ► A message received in one port is only sent back out the port the intended target node is on. ► No data collisions. ► Each node receives the full bandwidth available on the network. ► More than one node can ‘speak’ at once.

12. Network - Router ► Links 2 or more networks i.e. home or business networks to the Internet. ► It looks at the destination address of data passing through it and decided on the most efficient route. ► Directs traffic across the Internet.

13. Networking – Wide Area Networks Many large organisations, including governments and international companies, have widely scattered offices, possibly with each having its own LAN. A WAN is used to link all of these dispersed networks.

14. WANs ► WANs are geographically widespread, the can cover a city, country or stretch around the world.

15. WANs ► A WAN uses telecommunication systems owned by other companies and covering large distances ► WANs still use copper and fibre cables but also use satellite and microwave wireless communication.

16. WANs ► WANs are mainly used for file transfer, email, shared access to multi user databases and video conferencing. ► Not peripheral sharing. ► Bandwidth depends on the telecommunications link.

17. Intranet ► For internal company use only. ► Looks like a private version of the Internet. ► Mainly used to share company information via web pages and group work.

18. Internetwork ► A collection of two or more LANs. ► Connected via routers so all users and devices can communicate. ► The Internet is the largest example.

19. Internet Connection ► Dial – up ► Cable Modem ► ISDN ► ADSL ► Leased Line ► 56 Kbps ► Max of 36 Mbps but shared between users ► 1.5 Mbps ► 2 – 100 Mbps ► 1.5 – 274 Mbps T1 – T4 lines

20. Widespread use of Networks – Technical Reasons ► Processors – Becoming faster with more than one processor per chip. ► Memory – More memory means the development of more complex network operating systems. ► Data transfer rates – increasing. ► Improving network related software – browsers and operating systems.