Networks: LANs What hardware do you need for a LAN network? • File Server : Runs software, stores files. • Terminals : Workstations that give network access. • Print Server : Queues up all print jobs from users in network. • Cables (wire/optic) : Sends data • HUBS – joins computers in a network • Router – enables network to be connected to the internet (SKY Router)
Hardware – Buses • Buses are the lines of communication between the hardware devices within a computer system • All data that moves in a computer must use the buses that are available • There are different types of buses each with a different role • Address Bus: This identifies the memory location that is to be either written to or read from
Hardware – Buses • Data Bus: This bus transfers the data to and from the processor, to the identified memory location
Interfacing • Computing peripheral devices have different operating characteristics • When a device is connected to a computer, an interface is the hardware and software needed for the processor to be able to communicate with the device • Sometimes the interface hardware comes on an interface board, which has to be fitted into the computer
Interfacing • Commonly the peripheral is just connected via a socket • This is the port through which signals to and from the device travel • Serial/parallel • USB • Firewire • HDMI • MIDI • VGA etc
Handshaking • When two devices need to communicate, one device sends a message to the other • “are you ready to receive data?” • When the other is ready, it sends a signal back to the first device • “Yes I am ready to receive data” • Now the communication can begin • This exchange of preliminary signals is called handshaking
Networks Protocols • Protocol: A set of rules for transmitting data across a networkable to 'talk' or 'communicate' with one another and they do this by following a protocol. • Protocols have rules for • Detecting a connection • Handshaking • How to start a message • How to format a message • What to do about errors • How to detect a loss of connection and what to do next • Terminating a connection
Networks Protocols • HTTP: HyperText Transfer Protocol • Used for transferring web pages between a client and a server on the Internet • FTP: File Transfer Protocol • Used for transferring files from one computer to another – uploading a web page to a web server • SMTP: Simple Mail Transfer Protocol • Used for sending an email over the Internet • VoIP: Voice over Internet Protocol • Used for sending voiced messages over the Internet
Networks Protocols • Wireless • WAP • WAP stands for Wireless Application Protocol and is a popular type of mobile internet service which can be used on a handheld device, such as a mobile phone or PDA. It enables you to go online while out and about and is especially handy if you want to get the latest news updates, sports scores and travel updates. (Apple phones communicate with Android) • 3G and 4G taken over
Portable Devices • Any device that can be carried around with you • Laptop Computer • Battery powered computers that can be used anywhere • Most have network cards so that they can connect to a network either via a cable or a wireless connection • PDA Personal Digital Assistant) • A small hand-held portable computer • A palmtop computer
Wireless Networks • Radio waves can be used to transmit data from one computer to another • Each computer in a wireless network requires a wireless network card together with the software drivers • A wireless hub is connected to the network and transmits receives data from the computers
Wireless Networks - Advantages • No need for cabling • Computers can be used anywhere within range of the signal
Wireless Networks - Disadvantages • Data transmission speeds can be slow • Data signals can only be received within a limited range • Security maybe a problem as people may be able to pick up the data signals outside of your premises
Network Communications GCSE ICT
Networks: WANs What extra hardware do you need for a WAN network? • Modems :To connect up to a telephone system (instead of cable). How a modem works…
The Telephone Network in Computing • A modem is required for a computer to communicate over telephone lines • Data is converted from digital to analogue and then back again • The speed at which data is transmitted and/or received is measured in bits per second
Network Communications FAST BANDWIDTH SLOW BANDWIDTH Bandwidth tells us the rate at which data can be transmitted down the communications line in a given period of time. The current standard is 56,000 bits per second
Network Communications • The higher the bandwidth, the quicker the data will flow along the line… • Web pages loaded quicker. • Multimedia is downloaded faster. • Internet connection is faster. • Less network traffic. • Quicker response time.
Network Communications • There are a number of connection types available to us when we want to access the services from the Internet… Each one has a different BANDWIDTH. • PSTN : Public Switched Telephone Network. • ISDN : Integrated Services Digital Network. • ADSL : Asymmetric Digital Subscriber Line.
Public Switched Telephone Network PSTN for short. Uses traditional telephone system to allow access to the Internet. This is the telephone system used for making day-to-day telephone calls It is the main reason why computers have become so popular in recent years! Low Bandwidth Dial Up Connection.
Integrated Services Digital Network ISDN for short. Has a greater range of frequencies than PSTN, at least as twice as fast. Typical transfer rate of 128,000 bits per second Data is transmitted simultaneously Special connection and modem required Supports Videoconferencing, faxes and voice applications.
Asymmetric Digital Subscriber Line ADSL for short. Usually referred to as ‘Broadband.’ Is permanently switched on, no need for dial up to get a connection. Uses telephone lines to transmit data at very fast speeds (512,000 bits per second) ADSL modem and splitters required to separate telephone signal from the ADSL signal Has a high bandwidth. You can still make telephone calls when surfing the web!
Connecting to The Internet Single users can connect to the Internet. Special Hardware and Software is required to allow people to access the Internet. As well as an electronic device (PC, Tablet etc.) you need: Internet Service Provider. Browser Software. Telecommunications line e.g. ISDN, ADSL. Modem/Broadband Modem/ISDN adapter.
Network Security GCSE ICT
Learning Outcomes: • Understand how to secure a network. • Understand Dangers posed to networks. • Identify different types of security.
The Basics There are many ways to secure a network ranging from complicated around the clock security services to a simple lock and key. Security is now a major item in every network it can mean the difference between life and death for some businesses. Example: The play station network, was taken down by hackers and some of their customers credit card details stolen. This was all because the security on this network was weak or unprotected.
Network Security Physical security means that the hardware of the network is protected from theft and kept safe. Access security means that there is a limit to the amount of access a user has to the information held on the network. Data security means that there are measures taken to prevent the loss of data held on the system.
Ways of protecting you and your computer and network There are now many company's offering users different packages to protect and prevent your computer and or network. Most of theses packages detect, quarantine and delete infected files And some monitor the websites accessed and links to other servers and or networks.
Types of virus There are many types of virus for example there are: • Worm virus • Trojan houses virus • Boot sector virus • Macro virus • Root kit virus • Time bomb virus • Memory resistant virus • Polymeric virus
Physical security for a network As well as security software you will need to protect your network in more conventional ways i.e. lock and key. • Fire protection- fire doors, smoke doors, fire proof safes est. • Alarms-rooms containing the server should be alarmed • Locks-all rooms with services inside and have limited recorded access to them • Visibility-avoid putting computers on ground flour and where they are visible to passes bye
Data security There are many ways to prevent loss of your data: • Password protecting your data. • You can also set the information as read only so it can not be tampered with. • You can also back up data either as a hard copy of saved digitally. • You will also need to keep a log on access to your server, so that if the worst happens you can trace the perpetrator.