Explain LAN in computer networks vtu syllabus for exam 8marks
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A Local Area Network or LAN is a computer network that connects devices within a limited geographical area, typically within a single building or campus. LANs are characterized by high data transfer rates ranging from 10 megabits to 10 gigabits per second, private ownership, and low latency communication. They enable resource sharing such as printers, files, and internet connections among connected devices. The network is usually owned and controlled by a single organization, making it ideal for offices, schools, and homes.
LAN topologies define how network devices are physically or logically arranged. The Bus topology uses a single cable backbone with devices connected linearly and terminators at both ends. Star topology connects all devices to a central hub, making it easy to manage but creating a single point of failure. Ring topology forms a circular connection where data travels in one direction using token passing. Mesh topology provides multiple interconnected paths between devices, offering high redundancy but at increased complexity and cost. Each topology has distinct advantages and trade-offs in terms of cost, reliability, and performance.
LAN technologies define how data is transmitted over the network. Ethernet, following IEEE 802.3 standard, uses CSMA/CD protocol for collision detection and supports speeds from 10 megabits to 100 gigabits per second. It's the most widely deployed LAN technology using twisted pair or fiber optic cables. Token Ring, IEEE 802.5 standard, employs a token passing mechanism in a ring topology, operating at 4 or 16 megabits per second with deterministic access. Wi-Fi, based on IEEE 802.11 standards, provides wireless connectivity using CSMA/CA for collision avoidance, supporting speeds from 11 megabits to 9.6 gigabits per second across various radio frequency bands.
LAN components are essential hardware elements that enable network functionality. Network Interface Cards or NICs connect devices to the network, each having a unique MAC address for identification. Switches create separate collision domains for each port, learning MAC addresses and enabling full-duplex communication. Legacy hubs share collision domains and use half-duplex communication. Routers operate at the network layer, connecting different subnets and routing packets between networks. Various cable types include twisted pair for Ethernet, coaxial for older networks, and fiber optic for high-speed connections. Wireless access points bridge wired and wireless segments, providing connectivity to mobile devices.