ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 1 BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 2 What is a Network? A network consists of 2 or more computers connected together, and they can communicate and share resources (e.g. information) BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 3 Why Networking? Sharing information — i.e. data communication Do you prefer these? Or this? BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 4 devices that are connected in various ways in order to communicate and share resources Usually, the connections between computers in a network are made using physical wires or cablComputer network A collection of computing es However, some connections are wireless, using radio waves or infrared signals BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 5 Sharing hardware or software Centralize administration and support E.g. print document E.g. Internet-based, so everyone can access the same administrative or support application from their PCs BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking BY S K SATAPATHY 6 FEATURES 1.SPEED 2.SHARE DATA/INFORMATION 3.CENTRALISED DATA STORAGE.(BACKUP) 4.SECURITY 5. PRINT SERVICES(NETWORK PRINTER) 6.FLEXIBLE ACCESS 7.COST

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 7 How many kinds of Networks? Depending on one’s perspective, we can classify networks in different ways Based on transmission media: Wired (UTP, coaxial cables, fiber-optic cables) and Wireless Based on network size: LAN and WAN (and MAN) Based on management method: Peer-to-peer and Client/Server Based on topology (connectivity): Bus, Star, Ring … : BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 8 Two main categories: – Guided ― wires, cables – Unguided ― wireless transmission, e.g. radio, microwave, infrared, sound, sonar We will concentrate on guided media here: – Twisted-Pair cables:  Unshielded Twisted-Pair (UTP) cables  Shielded Twisted-Pair (STP) cables – Coaxial cables – Fiber-optic cables Transmission Media BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 9 If the pair of wires are not twisted, electromagnetic noises from, e.g., motors, will affect the closer wire more than the further one, thereby causing errors Twisted-Pair Cables BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 10 Unshielded Twisted-Pair (UTP) Typically wrapped inside a plastic cover (for mechanical protection) A sample UTP cable with 5 unshielded twisted pairs of wires Metal Insulator BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 11 Shielded Twisted-Pair (STP) STP cables are similar to UTP cables, except there is a metal foil or braided-metal-mesh cover that encases each pair of insulated wires BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 12 Categories of UTP Cables EIA classifies UTP cables according to the quality: Category 1 ― the lowest quality, only good for voice, mainly found in very old buildings, not recommended now Category 2 ― good for voice and low data rates (up to 4Mbps for low-speed token ring networks) Category 3 ― at least 3 twists per foot, for up to 10 Mbps (common in phone networks in residential buildings) Category 4 ― up to 16 Mbps (mainly for token rings) Category 5 (or 5e) ― up to 100 Mbps (common for networks targeted for high-speed data communications) Category 6 ― more twists than Cat 5, up to 1 Gbps BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 13 Local-area network (LAN) A network that connects a relatively small number of machines in a relatively close geographical area BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 14 LAN and WAN Local Area Network (LAN) Small network, short distance A room, a floor, a building Limited by no. of computers and distance covered Usually one kind of technology throughout the LAN Serve a department within an organization Examples: Network inside the Student Computer Room Network inside Building Network inside your home BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 15 Wide Area Network (WAN) A network that uses long-range telecommunication links to connect 2 or more LANs(diff network)/computers housed in different places far apart. Towns, states, countries Examples: Network of our Campus Internet WAN Student Computer Centre Your home USA BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 16 Example of WAN: Broadband Cable Network Cable TV services have been extensively developed in most modern cities Cable TV companies try to make use of their coaxial cable installed (that are supposed to carry TV signals) to deliver broadband data services BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 17 Wide-area network (WAN) A network that connects two or more local-area networks over a potentially large geographic distance Often one particular node on a LAN is set up to serve as a gateway to handle all communication going between that LAN and other networks Communication between networks is called internetworking The Internet, as we know it today, is essentially the ultimate wide-area network, spanning the entire globe BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 18 Metropolitan-area network (MAN) The communication infrastructures that have been developed in and around large cities BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 19 LAN : 1. LAN stands for Local Area Network. 2. Used Guided Media 3. A communication network linking a number of stations in same local area. 4. LAN generally provides a high-speed 100 Kbps to 100 Mbps. MAN: 1. MAN stands for Metropolitan Area Network. 2. Use may be Guided or may be Unguided media. 3. This network shares the characteristics of packet broadcasting networks. 4. A MAN is optimized for a large geographical area than LAN. WAN : 1. WAN stands for Wide Area Network. 2. Used Unguided media. 3. A communication network distinguished from a Local Area Network. 4. Its long distance communications, which may or may not be provided by public packet network. BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 20 LANMANWAN 1. LAN stands for Local Area Network. 2. Used Guided Media 3. A communication network linking a number of stations in same local area. 4. LAN generally provides a high-speed 100 Kbps to 100 Mbps. 1. MAN stands for Metropolitan Area Network. 2. Use may be Guided or may be Unguided media. 3. This network shares the characteristics of packet broadcasting networks. 4. A MAN is optimized for a large geographical area than LAN. 1. WAN stands for Wide Area Network. 2. Used Unguided media. 3. A communication network distinguished from a Local Area Network. 4. Its long distance communications, which may or may not be provided by public packet network. BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking Figure 15.1 Local-area networks connected across a distance to create a wide-area network BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 22 Peer-to-Peer Networks Peer-to-peer network is also called workgroup No hierarchy among computers  all are equal No administrator responsible for the network Peer-to-peer BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 23 Advantages of peer-to-peer networks: Low cost Simple to configure User has full accessibility of the computer Disadvantages of peer-to-peer networks: May have duplication in resources Difficult to impliment security policy Difficult to handle uneven loading(uneven load balancing even after several practice runsuneven load balancing even after several practice runs Where peer-to-peer network is appropriate: 10 or less users No specialized services required Security is not an issue Only limited growth in the foreseeable future BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 24 Clients and Servers Clients WorkstationNetwork Clients (Workstation) Computers that request network resources or services ServersNetwork Servers Computers that manage and provide network resources and services to clients Usually have more processing power, memory and hard disk space than clients Run Network Operating System that can manage not only data, but also users, groups, security, and applications on the network Servers often have a more stringent requirement on its performance and reliability BY S K SATAPATHY

ENG224 INFORMATION TECHNOLOGY – Part II 5. Introduction to Networking 25 Advantages of client/server networks Facilitate resource sharing – centrally administrate and control Facilitate system backup and improve fault tolerance Enhance security – only administrator can have access to Server Support more users – difficult to achieve with peer-to- peer networks Disadvantages of client/server networks High cost for Servers Need expert to configure the network Introduce a single point of failure to the system BY S K SATAPATHY