1. Networks

2. What is a network ? A group of computers and associated devices connected by communications facilities (both hardware and software) to share information and peripheral devices, such as printers and modems.

3. LAN? WAN? PAN? MAN?

4. LAN or WAN ? LAN Local area network WAN Wide area network PAN Personal area network MAN Metropolitan area network

5. Network protocol A protocol is a set of rules that governs the communication Between computers on a network Network protocols include: Ethernet (most widely used) Localtalk Token ring

6. Ethernet Each computer listens along the cable to see if it is clear before they transmit data through the network,if the network is clear the node (usually a computer) will transmit or wait for the line to be clear. If 2 nodes (computers) attempt to transmit at the same time a collision will occur, each computer will then back off, wait and retransmit

7. Network Topologies - Bus Server PC

8. Bus topology Advantages Easy to connect pc or peripheral Requires less cabling than other topologies Disadvantages Entire network breaks down if there is a break in the main cable Difficult to identify where the problem is coming from if network crashes Cannot be used as a stand alone solution in large buildings

9. Network Topologies - Ring PC Server

10. Ring topology Advantages All nodes have equal access Growth in the system has minimal effect on performance Because data travels in one direction high data transmission speeds are enabled Disadvantages Often the most expensive topology Failure of one computer may affect others

11. Network Topologies - Star Hub or Switch PC Server

12. Star topology Advantages Easy to install and wire No disruption to the the network when connecting or removing devices Easy to detect faults and remove parts Disadvantages Requires more cable than a bus If the hub fails the nodes attached are disabled More expensive than a bus

13. Network Topologies - Wireless Wireless Hub or Switch Server PC

14. Wireless topology Advantages No cables Can use remote access points (hotspots) Can convert wired networks to become wireless relatively inexpensively Disadvantages Data transfer speeds can be slower than cable networks Signal strength can sometimes be weak depending on location

15. Network Topologies - Hybrid Wireless Hub or Switch Hub or Switch PC Server

16. Network Topologies - Hybrid Wireless Hub or Switch Hub or Switch PC Server Classroom / Office

17. Hybrid topology Advantages One company can combine benefits of several different types of topology Workgroup efficiency can be customised Disadvantages Devices on one topology can ’ t be placed onto another topology without some hardware changes

18. Network Interface Cards Allows a computer to be connected to a network. Must be the right type for the network (e.g. Ethernet, Token Ring). RJ45 Connector

19. Network Cabling Depends on the network type, speed of operation and distance covered. Common types are: Twisted pair wire (Ethernet) Fibre Optic (FDDI)

20. Bluetooth PAN – Personal area network Named (bizarrely) after a 10 th century Danish king Replacing infrared as the instant transfer mode of choice with a better range and no line of sight restrictions Allows up to 8 devices to connect as a mini network (short range of 30ft) Devices include – Mobile phones, printers, PDA’s, GPS, digital cameras, keyboards and mice

21. Centrino technology Intel has branded a combination of technologies used in laptops under one name Pentium M (mobile) chip Wireless network connection capability 855 chipset (including graphics chip) Only Centrino if all 3 components included

22. Cable vs wireless Cabled network Pro ’ s Inexpensive Capabilty included on most pc ’ s Cons Requires cabling Additional hardware required for bigger networks such as hubs and switches Range 91m (300ft) per segment Wireless networks Pro’s No cabling Can use wireless access points anywhere (Hotspots) Cons Data speeds slower than Cabled networks Wireless capability only available on newer pc’s Range 30m (100ft)

23. Sharing Information Once PCs are networked, users may share each other files, printers and Internet connection. Hub or Switch Printer Internet PC

24. Network Operating System For much greater control over the sharing, access and security of files on a network. Familiar systems are: MS Windows 2000 Professional. Novelle Netware.

25. Internet The interconnection of a number of networks across the globe. Connected by a backbone of telephone lines, high speed ISP cable, satellite, undersea cable and wireless links. The different parts of the Internet (or any large WAN) are connected together using a number of devices including: Bridges, Routers, Repeaters and Switches.

26. Connecting to the Internet There are two types of Internet connection: Analogue – via a modem (typically 56 kBps) Broadband – via a broadband modem (typically 256 kbps, 512 kbps, 1 Mbps or 2 Mbps)

27. Installing Broadband You need to be in an area of broadband coverage (i.e you need an Asynchronous Digital Subscriber Network – ADSN – and BT need to reconfigure you to it). You need to sign up with a company to give you broadband (e.g. BT, Telewest). You need a Broadband modem.

28. Typical Broadband Configuration Modem could be wireless

29. Internet website suffixes.com or.co Commercial site, generally going to shed a Positive light on its product as always money behind it Academic or educational institutions Government sites Traditionally non-profit organisations, such as the Red cross, though sometimes there may be commercial Interests if the site is being sponsored Network, any kind of site can have this suffix as it Acts as a catch all for any sites not fitting into the other catorgories.edu or.ac.gov.org.net

30. Example country domain suffixes.uk United Kingdom.au Australia.in India.br Brazil.it Italy.ca Canada.mx Mexico.fr France.tw Taiwan.il Israel

31. Exercise / Activity Next week - Construct a small network. This week – Exercise 1 (network questions).