Networks By Indrani Chakraborty 1Copyright reserved to Indrani

What is a network? Two or more computer systems connected together so that they can share and exchange data Networks make better use of limited resources The definition is simple definition but the details are much more involved 2Copyright reserved to Indrani

Why do we network? Sharing information –File sharing – data between computers Sharing resources Centralizing administration and support Better communication 3Copyright reserved to Indrani

Traits of a good network Reliable - dependable Scalable – hardware and software can grow up or down as organization needs change Redundant – anticipates disaster – duplicate data and resource to minimize downtime and data loss Secure Good Speed 4Copyright reserved to Indrani

Some advantages of a network are: Resources (Hardware and Software) can be shared. Allows more effective communication between users e.g. via . Networks are cheaper than “stand-alone PCs.” Information held on the network can be accessed by all users with authorised access. 5Copyright reserved to Indrani

Some disadvantages of a network are: The set-up and maintenance costs can be expensive. A fault with the network server can cause difficulties with the organisation. Networks need security measures to restrict access to users. WANs are vulnerable to hackers and viruses. 6Copyright reserved to Indrani

Networks What is a Network? What is a LAN? What hardware do you need to make one? What is a WAN? What hardware do you need to make one? What are the advantages and disadvantages of a network? Draw a star, ring and bus network – give advantages and disadvantages of each. 7Copyright reserved to

Networks A network is two or more computers connected together so they can communicate which each other. There are 2 main types of network… Computer 1 Computer 2 8Copyright reserved to

LAN LAN stands for: LOCAL AREA NETWORK LANs are networks that are found where computers within a building need to communicate. They are Small and Local! 9Copyright reserved to

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. 10Copyright reserved to

Different types of LAN Topologies 11Copyright reserved to Indrani Ring Network Bus Network Star Network Tree Network

Network Topologies There are 3 main types of network topologies: The Ring Network The Bus Network The Star Network 12Copyright reserved to Indrani

The Ring Topologies Computers are connected together to form a ring shape so that none of them is more important than any of the others. 13Copyright reserved to Indrani

Advantages: They are cheap to expand. The data flows around the network in one direction so it is fast. There is no reliance on a central computer. Disadvantages: If there are a lot of users on the network, it could slow down as all the data is sent along a single line. If one computer in the ring stops working, the whole network stops. 14Copyright reserved to Indrani The Ring Topologies

The Bus (or line) Topologies Computers are connected like bus stops on a main road. None of them is more important than any of the others. 15Copyright reserved to Indrani

Advantages: It is cheap as it uses the least amount of cable. More computers can be added without disruption. Disadvantages: With a lot of users, the network will be slow as data has to travel through the same central cable. Failure of the central cable will stop the network from working. 16Copyright reserved to Indrani The Bus (or line) Topologies

The Star Topologies Computers are connected like a star to a central computer such as a mainframe. This is also called the “host” computer. 17Copyright reserved to Indrani

Advantages: If a cable fails, it will only affect one workstation. More computers can be added without disruption. Disadvantages: It is more expensive as it uses the most cabling. Failure of the central computer will stop the network from working. 18Copyright reserved to The Star Topologies

WAN WAN stands for: WIDE AREA NETWORK WANs are networks that are found where computers in different areas or countries need to communicate. They are long range and not local! 19Copyright reserved to

What extra hardware do you need for a WAN network ? Modems : To connect up to a telephone system (instead of cable). 20Copyright reserved to

WLAN WAN stands for: WIRELESS LOCAL AREA NETWORK WLANs are networks which provide wireless network communication over a few meters using radio or infrared signals instead of cables. 21 Copyright reserved to Indrani

What extra hardware do you need for a WAN network ? Copyright reserved to Wireless Access Point : In computer networking, a wireless access point (WAP) is a device that allows wireless devices to connect to a wired network using Wi- Fi, Bluetooth or related standards. The WAP usually connects to a router (via a wired network) if it's a standalone device, or is part of a router itself.computer networkingWi- FiBluetoothrouter

WiFi Wi-Fi is a popular technology that allows an electronic device to exchange data wirelessly (using radio waves) over a computer network, including high-speed Internet connections. The Wi-Fi Alliance defines Wi-Fi as any "wireless local area network (WLAN) products that are based on the Institute of Electrical and Electronics Engineers' (IEEE) standards". [1] However, since most modern WLANs are based on these standards, the term "Wi-Fi" is used in general English as a synonym for "WLAN".wirelesslyradio wavescomputer networkhigh-speed InternetWi-Fi Alliancewireless local area networkInstitute of Electrical and Electronics Engineers [1] Copyright reserved to 23

BLUETOOTH Bluetooth is a specification (IEEE ) for the use of low- power radio communications to link phones, computers and other network devices over short distances without wires. The name Bluetooth is borrowed from Harald Bluetooth, a king in Denmark more than 1,000 years ago(due to his abilities to make diverse factions communicate with each other. The Bluetooth logo consists of the Nordic runes for his initials, H and B)runes.Bluetooth technology was designed primarily to support simple wireless networking of personal consumer devices and peripherals, including cell phones, PDAs, and wireless headsets. Wireless signals transmitted with Bluetooth cover short distances, typically up to 30 feet (10 meters). Bluetooth devices generally communicate at less than 1 Mbps.Mbps Copyright reserved to 24

MODEM A modem (modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from light emitting diodes to radio. The most familiar example is avoice band modem that turns the digital data of a personal computer into modulated electrical signals in the voice frequency range of a telephonechannel. These signals can be transmitted over telephone lines and demodulated by another modem at the receiver side to recover the digital data.analog carrier signaldigital informationsignallight emitting diodesradiovoice banddigital datapersonal computerelectrical signalsvoice frequencytelephonetelephone lines Copyright reserved to 25

Networks: Security Because networks are almost vital to an organisation’s daily activities, they must be kept safe and secure… There are 3 main types of network security… Physical, Access and Data. 26Copyright reserved to Indrani

Networks: Security Physical security means that the hardware of the network is protected from theft and kept safe. 27Copyright reserved to Indrani

Networks: Security Access security means that there is a limit to the amount of access a user has to the information held on the network. 28Copyright reserved to Indrani

Networks: Security Data security means that there are measures taken to prevent the loss of data held on the system. 29Copyright reserved to Indrani