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Outcome 2: Networks

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Communications When computers were first introduced, they were standalone devices. As they became widely used, manufacturers designed hardware & software so each could communicate with each other. Originally only large computers had the ability to communicate with another, however today, the landscape has changed dramatically, with even the smallest computers and devices being able to communicate with each other.

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Communications For successful communications between two devices, you need: A sending device that initiates an instruction to transmit data/information/instructions A communications device that converts the data/information/instructions into a usable signal carried by the transmission media Transmission media, on which the signal travels A communications device that converts the data/information/instructions into a usable signal that the receiving device can use A receiving device that accepts the data, instructions, or information.

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Communications Sending devices can usually also serve as receiving devices Laptops, PCs, mobile phones, GPS devices Primary function of a communications device (i.e. broadband router) is to transmit data/information/ instructions between a sending & receiving device.

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Communications Transmission media include CAT5/6, coaxial cabling, WiFi. Data, information & instructions travel along transmission media (aka a communications channel), either in analog or digital form. Computers process data as digital signals so when using a standard telephone line as the communications channel, a modem (modulation- demodulation) to convert the digital signal into an analog one & vice versa.

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Communications Modems convert the individual electrical pulses of a digital signal into analog signals for data transmission over telephone lines. At the receiving computer, another modem converts the signals back into digital signals that the computer can process.

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What is a network? A network is a collection of computers and devices connected together via communication devices & transmission media, allowing computers to share resources with one another.

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What is a network? Networks can be internal to an organisation or cover the whole world by connecting to the Internet. Networks exist for sharing the information required for an individual to get the job done. Sharing resources, such as hardware & software, also makes a network a valuable asset.

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Advantages of using a network Facilitating communications Sharing hardware

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Advantages of using a network Sharing software ______________________________ Sharing data and information ______________________________ Transferring funds ______________________________

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Activity List the hardware that is shared over the MacKillop network List (some of) the data & information that is shared over the MacKillop network

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Disadvantages of using a network User dependence ___________________________________ Network Management ____________________________________

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Types of networks The two basic types of networks are: Local Area Network (LAN) Wide Area Network (WAN)

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Local Area Networks (LAN) A Local Area Network (LAN) connects computers & devices in a small geographical area. Examples Home School Office building Each computer or device connected on the network is known as a node. Often nodes are connected to the LAN with cabling.

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Wireless Local Area Networks (WLAN) A wireless LAN (aka WLAN) uses minimal physical wiring, using wireless mediums (radio waves) instead. To do this, computers & devices must have wireless capability, whether that be in-built or ad-hoc.

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Wireless Local Area Networks (WLAN) Usually a WLAN will communicate with a traditional (wired) LAN for access to resources, such as software, hardware & the Internet.

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Network Operating Systems (NOS) A Network Operating System (NOS) is the system software that organises, controls & co-ordinates the communications over a LAN. Tasks performed by the NOS include: Administration Adding/deleting users & performing backup operations File/Printer management Locating/transferring files Prioritising print jobs Security Monitoring & restricting access to network resources

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Network Operating Systems (NOS) Three significant providers of NOS at present Microsoft (Windows Server 20xx) Dominant market share Apple (Apple Workgroups Server) Novell(Netware)

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Types of LAN Local Peer-to-Peer (P2P) A P2P network is a simple, inexpensive network in which each node shares hardware & data with all of the other nodes (computers) on the network. Each computer stores files on its own storage devices thus each computer in the network contains both the NOS & application software. Ideal for home users and very small businesses. Some operating systems like Microsoft Windows include P2P utilities that allow you to set up a basic P2P network.

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Types of LAN Client-Server A client-server network is a network in which one or more computers act as a host (server) & the other computers (clients) on the network can request services from the server. The major difference between the server and client computers is that the server has more storage space & is more powerful. Some servers have dedicated tasks (i.e. file/print servers). Generally, C-S networks are used in organisations with more than 10 computers. Most client-server LANs have a Network Administrator due to their larger sizes. The network admin is the person/people in charge of the network. Costs associated with a server-based network are significantly higher than those for a P2P network due to equipment costs required at startup and ongoing tech support.

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Activity Suggest reasons why a peer-to-peer network would not be used in organisations in more than ten computers.

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Wide Area Networks (WAN) WANs connect larger areas, such as whole states, or even the world. Transoceanic cables and satellites are used to connect WANs

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Types of WAN Internet P2P Internet P2P networks involve users with the same networking software to connect to each others hard disks with the intention of directly exchanging files. To maintain acceptable network speeds, most Internet P2P networking applications limit the clients connected to a particular client at the one time. Many businesses see an advantage to using P2P as it allows their employees to exchange files, hence freeing the company up from maintaining a network for this purpose.

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Types of WAN Internet P2P Two examples of networking software that enable Internet P2P are Kazaa & LimeWire. These programs were controversial (when they were the BIG thing) in respect to copyright infringement of music. Using Internet P2P file sharing programs also expose your computer to possible security threats such as viruses & botnets.

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Activity What type of network does MacKillop use? Justify your answer.

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Topology The physical topology of a network refers to the configuration of cables, computers and other peripherals. The main types of network topologies are: Bus Star Hybrid

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Network Topologies: Bus A bus topology consists of a main run of cable with a terminator at each end. All servers workstations and peripherals are connected to the linear cable

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Network Topologies: Star A star network is designed with each node (file server, workstation, peripheral) connected directly to a central network hub or server

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Network Topologies: Hybrid A hybrid topology combines characteristics of bus and/or star topologies. It consists of groups of star-configured workstations connected to a bus backbone cable

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Activity Read the section on Types of Network Topologies on pages 54 & 55. List the advantages & disadvantages for each type of network topology.

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Intranets An intranet is an internal network within an organisation that uses internet & web technologies.

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Intranets Common characteristics of Intranets Use a web server Support various types of multimedia Accessible via web browsers

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Intranets Organisations employ the use of an intranet to publish calendars, policies, manuals and to allow access to documents required by the users. Intranets typically include connections to the Internet, allowing employees access to relevant information from the web.

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Intranets Benefits of using an Intranet Allows restricted access to company information Facilitates communication Reduced paper usage Ease of use

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Intranets Benefits of using an Intranet Global Access Ability to use multimedia Connection across different network platforms Dynamic information

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Activity What are the benefits associated with an Intranet being used in a school environment? Use MacKillops Intranet as a reference point.