Lecture 07-Introduction to Networking.pdf

Introduction to Networking BST12113 - Lecture 6 Nuwan Rajarathna ICT Centre Wayamba University of Sri Lanka Makandura, Gonawila. What is a Network? A network, is a group of people/ system of device...

Introduction to Networking BST12113 - Lecture 6 Nuwan Rajarathna ICT Centre Wayamba University of Sri Lanka Makandura, Gonawila. What is a Network? A network, is a group of people/ system of devices, connected together to share / exchange data. What is a Computer Network? Computer Network is a collection of computing devices (nodes) that are connected together in order to communicate and share resources. A network connected by wired (physical) and/or wireless connections These networked devices use a system of rules, called communications protocols, to transmit information over wired or wireless technologies. Sketch of a simple network Sketch of a network  Why we use Networks? Advantages When a computer connected to a network, that allows us to… Easily share files and data Share resources such as printers and Internet connections Communicate with other network users (e-mail, instant messaging, video- conferencing, etc.) Store data centrally (using a file server) for ease of access and back-up Keep all of our settings centrally so we can use any workstation To overcome geographic separation  Disadvantage of using Networks A network connected computer… is vulnerable to hackers Entire systems depend on main server, If the main server breaks, system cannot work (robustness) If the network breaks, many tasks become very difficult can more easily be attacked by a virus Complexity of managing a large network – requires training and professionals Malware (Viruses, Worms) can spread to other computers Implementation (cabling and file servers purchase) and maintenance are expensive More data traffic ( network congestions)  Nodes in a Network A node can be a computer, printer, or any other device capable of sending/receiving data generated by other nodes in the network Each node is an endpoint for data transmissions or redistribution  Computers in a Network Computers connected together to create a network fall into two categories: servers and clients (workstations) Clients Client computers, or workstations, are the normal computers that people sit at to get their work done. Servers Servers are special, powerful computers that provide ‘services’ to the client computers on the network  Types of Network Local Area Network (LAN) Metropolitan Area Network (MAN) Wide Area Network (WAN) Personal Area Network (PAN) Storage Area Network (SAN) Wireless Local Area Network (WLAN) Virtual Private Network (VPN) Local Area Network - LAN A LAN is a computer network that interconnects computers within a limited area (one building or site ) such as a residence, school or office building Often a LAN is a private network belonging to an organization or business. Because LANs are geographically small, they usually use cables or low-power radio (wireless) for the connections  Wireless Local Area Network -WLAN WLAN is a LAN that uses radio signals (WiFi) to connect computers instead of cables WLANs use high-frequency radio waves and often include an access point to the Internet Typically, the range of a wireless connection is about 50m, but it depends how many walls, etc. are in the way. Wide Area Network (WAN) A WAN is a network that extends over a large geographical distance. A WAN is often created by joining several LANs together (Internet is the world largest WAN) Since WANs cover large geographical area, it use fiber optic cables, satellite radio links, microwave radio links as connection technologies  Metropolitan Area Network -MAN MAN is a larger network that usually spans several buildings in the same city or town A MAN is much larger than the standard LAN, but is not as large as a WAN  Personal Area Network - PAN PAN, is a computer network that enables communication between computer devices near a person. PANs can be wired, such as USB or FireWire, or they can be wireless, such as infrared, Bluetooth and ultra wideband. Storage Area Network -SAN SAN is a sub-network of storage devices that are shared with one another over a high-speed network connection SANs are primarily used to enhance storage devices, such as disk arrays and tape libraries  Virtual Private Network -VPN VPN creates a secure tunnel between two or more devices VPN extends a private network across a public network, and enables users to send and receive data across shared or public networks. It hides your IP address from corporations, government agencies and would-be hackers VPN, allow users to securely access a private network and share data remotely through public networks.  VPN VPNs are commonly used to allow an employee with a large company to connect to the company's intranet VPN encrypt all data on VPN tunnel, increase reliability of data transmission (It hides your online identity, ensuring that you are able to browse the Internet securely and anonymously) VPN reduce cost for equipment maintenance thus it is wireless and operate through Internet Network Topology Network topology defines the structure of the network. “how the different parts are arranged and connected together in a network” The structure of the network: o Physical topology Actual layout of the media o Logical topology How the hosts access the media Physical topologies  Bus topology Uses a single backbone cable (a long, central cable) All hosts connect directly to backbone cheap to install Can be quite slow Entire Network fail if fault in backbone  Ring topology Connects each host to the next, and the last to the first (each computer is connected to a loop of cable ) This creates a physical ring of cable o can span larger distances than other types of networks Star topology Connects all devices (server & hosts) to a central point of concentration, this point is usually a hub or switch This is the most common network topology in LANs o quite expensive to install o one malfunctioning node doesn't affect the rest of the network o will stop working if the central device breaks  Extended Star topology made up of all connected individual star topologies extend a physical star topology by one or more repeaters between the central node and the peripheral nodes Hybrid topology known as hybrid network hybrid topology produced when two different basic network topologies are connected.  Mesh topology each computer and network device is interconnected with one another (all nodes are interconnected) Can handle high amounts of traffic A failure of one device does not cause a break in the network or transmission of data. The cost to implement is higher than other network topologies Building and maintaining the topology is difficult and time consuming  Internet / Intranet / Extranet Based on organizational intent, networks can be classified as Internet / Intranet / Extranet  Internet The Internet is the global system of interconnected computer networks (that use the Internet protocol suite) to link devices worldwide. Who owns the Internet? Nobody does. No single person or company owns the Internet or even controls it entirely. As a WAN, it is made up of many smaller networks. These smaller networks are often owned and managed by a person or organization  Intranet Intranet is a set of networks that is maintained and controlled by a single entity. It is generally the most secure network type, with access to authorized users alone Intranet is a private network accessible only to an organization's staff The main purpose of an intranet is to share organization information and computing resources among employees.  Extranet An extranet is a computer network that allows controlled access from the outside, for specific business or educational purposes with partners, customers, or remote employees.  Network Host / Node A network host is a computer or other device connected to a computer network. A network host is a network node that is assigned a network address. Computers participating in the Internet are called Internet hosts A network address is an identifier for a node or host on a telecommunications network  Media Access Control (MAC) address A MAC address is a number that identifies the network adapter(s) installed on your computer/ device. MAC addresses are 6-byte (48-bits) in length, and are written in MM:MM:MM:SS:SS:SS format. The first 3-bytes are ID number of the manufacturer. The second 3-bytes are serial number assigned by the manufacturer. Internet Protocol address An IP address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. It’s uniquely identifies every device on the internet/network An IP address serves two principal functions network interface identification location addressing.  IP versions Internet Protocol version 4 (IPv4) - defines an IP address as a 32-bit number. (stored in four bytes) (Numeric dot-decimal notation - 4.29×109 address space) 172.16.129.12 192.248.89.10 Internet Protocol version 6 (IPv6) - a new version of IP, defines using 128 bits number – (alphanumeric hexadecimal notation - 3.4×1038 address space) 0:0:0:0:0:ffff:ac10:810c 2402:4000:2382:1a5e:48e4:4f9d:3175:5cda  How to see your IP address Click on the search box and type cmd. A command line window will open. Type ipconfig and press enter. look for "IPv4 Address.“ in Ethernet adapter