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Basics of Network

Network: When you have two or more computers connected to each other, you have a network. The purpose of a network is to enable the sharing of files and information between multiple systems. The Internet could be described as a global network of networks. Computer networks can be connected through cables, such as Ethernet cables or phone lines, or wirelessly, using wireless networking cards that send and receive data through the air. Types of Network: • LAN - Local Area Network • WLAN - Wireless Local Area Network • WAN - Wide Area Network • MAN - Metropolitan Area Network • SAN - Storage Area Network, System Area Network, Server Area Network, or sometimes Small Area Network • CAN - Campus Area Network, Controller Area Network, or sometimes Cluster Area Network • PAN - Personal Area Network • DAN - Desk Area Network LAN and WAN were the original categories of area networks, while the others have gradually emerged over many years of technology evolution. LAN - Local Area Network A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet. In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organisation. They also tend to use certain connectivity technologies, primarily Ethernet and Token Ring

WAN - Wide Area Network As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the Earth. A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a WAN. In IP networking, the router maintains both a LAN address and a WAN address. A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any one organisation but rather exist under collective or distributed ownership and management. LAN, WAN and Home Networking Residences typically employ one LAN and connect to the Internet WAN via an Internet Service Provider (ISP) using a broadband modem. The ISP provides a WAN IP address to the modem, and all of the computers on the home network use LAN (so-called private) IP addresses. All computers on the home LAN can communicate directly with each other but must go through a central gateway, typically a broadband router, to reach the ISP. Other Types of Area Networks While LAN and WAN are by far the most popular network types mentioned, you may also commonly see references to these others: • Wireless Local Area Network - a LAN based on WiFi wireless network technology • Metropolitan Area Network - a network spanning a physical area larger than a LAN but smaller than a WAN, such as a city. A MAN is typically owned an operated by a single entity such as a government body or large corporation. • Campus Area Network - a network spanning multiple LANs but smaller than a MAN, such as on a university or local business campus. • Storage Area Network - connects servers to data storage devices through a technology like Fiber Channel. • System Area Network - links high-performance computers with high-speed connections in a cluster configuration also known as Cluster Area Network.

Protocols: A network protocol defines rules and conventions for communication between network devices. Protocols for computer networking all generally use packet switching techniques to send and receive messages in the form of packets. Network protocols include mechanisms for devices to identify and make connections with each other, as well as formatting rules that specify how data is packaged into messages sent and received. Some protocols also support message acknowledgement and data compression designed for reliable and/or high-performance network communication. Hundreds of different computer network protocols have been developed each designed for specific purposes and environments. Internet Protocols The Internet Protocol family contains a set of related (and among the most widely used network protocols. Besides Internet Protocol (IP) itself, higher-level protocols like TCP, UDP, HTTP, and FTP all integrate with IP to provide additional capabilities. Similarly, lower-level Internet Protocols like ARP and ICMP also co-exist with IP. These higher level protocols interact more closely with applications like Web browsers while lower-level protocols interact with network adapters and other computer hardware. Routing Protocols Routing protocols are designed specifically for use by network routers on the Internet. Common routeing protocols include EIGRP, OSPF and BGP.
Some Basic Protocols:
1. ARP: Address Resolution Protocol
The address resolution protocol (ARP) is a protocol used by the Internet Protocol (IP), to map IP network addresses to the hardware addresses used by a data link protocol. The protocol operates below the network layer as a part of the interface between the OSI network and OSI link layer. It is used when IPv4 is used over Ethernet.
2. IP: Internet Protocol Address An Internet Protocol is a set of rules which govern Internet activity and facilitate completion of a variety of actions on the (www) World Wide Web.

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