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Information TechnologyUnit 1 Outcome 2: NetworksProtocolsNetwork communication protocolsThe networks of today connect terminals, devices and computers from many different manufacturers across many types of networks. For the different devices on several types of networks to be able to communicate, the networks must use similar techniques of moving data from one application to another.

Network standards have been developed by organisations such as the Institute of Electrical & Electronics Engineers (IEEE) to avoid issues with incompatibility.

Network communication protocolsA network standard defines guidelines that:The way computers access the medium to which they are attachedThe type of medium usedThe speed at which data flows The physical technology used

A standard that defines how two network devices communicate is called a protocol.

Manufacturers of both hardware and software must design their products in accordance with the appropriate standards to ensure their devices have the ability to communicate with a large range of networks.

Without standards, only hardware and software from the same company could be used together. Think of it this way.Network protocols are like a language. Think of a computer as a person.

The language that the person speaks is the network protocol. Only two people who speak the same language can communicate with each other.

Similarly, only computers with the same network protocol can communicate on the network. Just like some people can speak several languages, networked computers may have several different protocols installed and running.Network communication protocolsEthernetEthernet is a standard communications protocol embedded in software and hardware devices that allow computers to operate a LAN.

Developed in 1973, and has since become the standard model for use in LANs worldwide.

Uses the CSMA/CD (Carrier Sense Multiple Access/ Collision Detection) access method.

A message to be communicated over a network can be broken into small pieces called packets, by the network protocol standard.What does that mean?Each computer in the network listens to the cable before sending anything through the network. If the network is clear, the computer will transmit the packet. If another computer is already transmitting on the cable, the computer will wait and try again when the line is clear.Each packet is sent independently over the transmission media. Once all of the packets arrive at the receiving computer, they are put back together to produce the original message.

A bit like waiting for your younger sister to get off the telephone perhaps?

Network Communications ProtocolsEthernet protocol allows for data to be transmitted over twisted pair, coaxial or fiber optic cable at a speed of 10 MbpsMore on this later though.

Fast EthernetTo allow for faster transmission, the Ethernet protocol has developed a new standard that supports 100 MbpsFast Ethernet requires the use of more expensive equipment and network cardsGigabit EthernetThe Ethernet protocol has also developed another new standard that allows transmission of 1 Gbps (gigabit per second)Network communication protocolsTCP/IPTCP/IP is the protocol that is used for the transmission of information over the InternetTCP (Transport Control Protocol) - used to break apart and rebuild information that travels over the Internet IP (Internet Protocol) - the main delivery system for information over the Internet Each computer that resides on a network has a unique IP address that is comprised of 4 numbers that range between 0 and 255. For example, 172.16.1.1, 192.85.255.10, 10.0.0.1

Network communication protocolsTCP/IPWhen a computer sends data over a network, the data is divided into packets. Each packet contains the data, origin (sender) & destination (recipient) information, and sequence information (used to reassemble the data at the destination).

Packets are then sent across the network using the fastest available path, avoiding congestion & broken links.

This technique of sending data across a network is called packet switching.

ActivityRead the issue Are we running out of IP addresses? on page 57 and answer the following questions.

Do you think organisations should be forced to adopt IPv6 to increase the number of addresses available?Do you think that the demand for IP addresses will increase over the next few years in the same way it has over the last ten years or will there be an escalation in demand? If an escalation was to occur, what might be the trigger?

Other network protocolsWhile Ethernet & TCP/IP are now standard in networks around the world, there are alternative protocols that are used.Common protocols include:802.11x (WiFi)Wireless Application Protocol

Apple: Apple File Protocol (AFP) Microsoft: NetBIOS Extended User Interface (NetBEUI)Novell: Sequential Packet Exchange (SPX)Novell: Internetwork Packet Exchange (IPX)Other network protocolsThe 802.11 standardDeveloped by the IEEE to specify how two wireless computers or devices communicate using radio waves.Uses techniques similar to Ethernet.The range of wireless communications is around 300m in open areas & approximately 50m inside buildings.Wireless networks are popular in locations where there is no existing wired system or it is difficult to install a wired network.

There are 4 subcategories of the 802.11 standard (a, b, g, n)Other network protocolsWireless Application Protocol (WAP)WAP allows wireless mobile devices to access the Internet & its services.Uses a client-server networkThe device contains the client software, and connects to the ISPs server.WAP-enabled devices include web-enabled telephones, pagers and hand-held computers.As the demand for wireless Internet access grows, the availability of WAP-enabled devices will increase.Sending & receiving devicesSending & receiving devices initiate or accept the transmission of data, instructions and information.

Desktops, notebooks, netbooks, TabletPCs, servers, mainframes are all examples of computers that can serve as sending & receiving devices as they can communicate directly with another computer, with hundreds of computers on a single network or with millions of other computers over the Internet.Sending & receiving devicesMobile devices, such as smartphones, PDAs, portable media players, portable games consoles, navigation systems & digital cameras, are compact, lightweight, easily carried and often enable connections with high-speed wireless broadband Internet.

They can usually be synced with personal computers to share & exchange information & install applications. They can also allow users to chat, send emails & access the Web.ActivityRead the issue Implanting computer chips: a new use for GPS on page 60 & answer the following questions.

What are the implications of microchip implanting?Would you permit a microchip to be implanted in your body? Why? Why not?

The technology could be used as a method to track people on probation, eliminate kidnapping or locate lost elderly people. Do you agree? Is this an invasion of privacy?What are the ethical issues surrounding this technology?ActivityThe next few slides titled Sending & receiving devices have been left blank on purpose.

You all know what these devices are, having used them either at home or at school.

You are required to write a short paragraph describing what each device is, what the device does, as well as their respective advantages & disadvantages.

Personal experiences, the text book (pages 59-68), as well as the Internet, would all be good references for this activity.Sending & receiving devicesMobile devices connected to networksSmart phonesActivityRead the issue Future directions for smart phones on page 63 & answer the following questions.

How could a smart phone replace a drivers licence or a passport?

Is this a direction in which technology should be heading?Sending & receiving devicesMobile devices connected to networksPDAs

Sending & receiving devicesMobile devices connected to networksHand-held computers

Case Study: British Sky Broadcasting Read the case study on page 64 and answer the following questions.

What benefits are British Sky Broadcasting likely to realise through the issue of hand-held computers to its technicians?

What is likely to be the impact on the technicians?Sending & receiving devicesMobile devices connected to networksNetbooks

Sending & receiving devicesMobile devices connected to networksPortable media players

Sending & receiving devicesMobile devices connected to networksNavigation systems

ActivityRead the issue Live traffic reports coming to a GPS near you on page 66 & answer the following questions.

What benefits are there for VicRoads making its traffic sensor data free available to GPS mapping services?Sending & receiving devicesMobile devices connected to networksDigital cameras

Communication devicesA communications device is any type of hardware capable of transmitting data, instructions or information between a sending device and a receiving device.

Depending on the devices and the media to be used for transmission, the communications device may need to convert an analog signal into a digital signal or vice versa.Communications devicesCommon types of communications devicesModemsAsymmetric digital subscriber line (ADSL) modemsCable modemsNetwork Interface Cards (NICs)Wireless Access Points (WAPs)Switches & routersCommunications devicesModemsAs mentioned last lesson, a computers digital signal must be converted into analog signals before they are transmitted over standard telephone lines.

Dial-up modems perform these conversions, and both the send & receiving ends of a communication channel must have a modem for data transmission to occur. Where digital lines are available, a different type of modem is required depending on the type of channel to be used.

ExamplesADSL/ADSL 2+Cable

NB: Even though no conversion occurs, the term modem is still used. Communications devicesNetwork Interface Cards (NICs)A Network Interface Card (NIC) is a communications devices that enables a computer that does not have in-built network capability to communicate with a network.

It can either be built-in to the motherboard of a computer, or inserted into an expansion slot of a PC or laptop. They can also be built into a number of peripheral devices, such as printers and scanners.

Communications devicesNetwork Interface Cards (NICs)NICs have three main functions:Increases the strength of the signal from the computerPackages the data for transmissionControls access to/from the network cable.

NICs for desktop computers typically have a port for a cable to be connected, whereas NICs for laptop computers would typically give the laptop the ability to connect to a wireless network.

Wired NICWireless NICCommunications devicesWireless Access Points (WAPs)A WAP is a central communications device that allows computers and devices to transmit data wirelessly among themselves.

WAPs are normally placed near ceilings, though often connected to a wired network backbone for faster transmission of data to the network server.Communications devices

Communications devicesSwitches & routersA switch is a device that provides a common connection point for nodes on a network.

A router is a communications device that connects multiple network areas or multiple networks together.Communications devicesHow switches & routers work?A switch stores the address of every device down to each cable connected to it. When a packet enters the switch, it uses simple logic to detect the destination of the packet & sends it down the only cable that contains the addressed device.

The result is that the packet reaches its destination quicker & without colliding with the packets being sent to the other nodes.Communications devicesHow switches & routers work?Routers are the only devices on the network that knows the addresses of each computer connected to the network, as well as each message sent by any computer.

Ill explain this using the image on the next slideCommunications devices

Communications devicesHow switches & routers work?A router will connect LANs & WANs irrespective of the hardware and protocols used on each segment of the network.

Broadband routers for home networks also have the ability to join multiple networks. These are specifically designed to join the home network (LAN) to the Internet (WAN) for the purpose of Internet connection sharing. In contrast, switches are not capable of joining large multiple networks or sharing an Internet connection.

Communications devicesHow switches & routers work?A home network with only switches must designate one computer as the gateway to the Internet and that device must have two network adapters one to connect to the home (LAN) & one to connect to the Internet (WAN).

Routers dont need to have a computer serve as the gateway as they are designed to perform all required functions.