The infrastructure of a Local Area Network (LAN) consists of the hardware and devices that allow computers and other network equipment to communicate with each other. In offices, schools, and other organizations, a LAN usually includes Ethernet cables, one or more network switches, routers, and other networking devices.
A network switch is one of the most important components of a LAN. It connects multiple computers and devices using Ethernet cables and allows them to exchange data quickly and efficiently. The switch can also be connected to a router, cable modem, or ADSL modem to provide Internet access to all devices on the network. In most homes, a single router performs both routing and switching functions, while a wireless repeater may be used to extend the Wi-Fi signal to areas with weak network coverage.
A LAN may also include additional devices such as firewalls, which protect the network from unauthorized access, load balancers, which distribute network traffic across multiple devices to improve performance, and network intrusion detection systems (NIDS), which monitor the network for suspicious or malicious activities.
Wireless devices such as laptops, smartphones, and tablets connect to the LAN through a wireless access point (WAP). If a router has a built-in wireless access point, it is called a wireless router, allowing both wired and wireless devices to connect to the same network.
Large and advanced LANs use redundant links between switches to improve reliability. These networks use the Spanning Tree Protocol (STP) to prevent loops that can disrupt network communication. They also use Quality of Service (QoS) to prioritize important traffic, such as voice and video calls, over less important data. Virtual Local Area Networks (VLANs) are used to divide a single physical network into multiple logical networks, improving security, performance, and network management.
A network bridge is another networking device that connects two LANs or different LAN segments. It allows devices on separate network segments to communicate with each other and can also be used to connect wired devices to a wireless network.
Network Topology
Network topology refers to the physical or logical arrangement of computers, networking devices, and communication links within a network. The choice of topology affects the performance, reliability, maintenance, and scalability of the network.
Several types of LAN topologies have been used over the years, including star, ring, bus, tree, and mesh topologies. Among these, the star topology is the most commonly used because it is simple to install, easy to manage, and reliable. In a star topology, all devices are connected to a central switch or hub. If one cable fails, the other devices continue to function normally, making the network more dependable.
Wireless Local Area Networks (WLANs) also use different network topologies. An Independent Basic Service Set (IBSS), also known as an ad-hoc network, allows devices to communicate directly with one another without using a wireless access point. This type of network is suitable for temporary or small-scale connections. Another common topology is the Basic Service Set (BSS), also called an infrastructure network, where all wireless devices communicate through a wireless access point. This is the standard topology used in homes, offices, schools, and public Wi-Fi networks.
Network Layer Configuration
Every device connected to a Local Area Network requires a unique Internet Protocol (IP) address for communication. In most LANs, IP addresses are assigned automatically using the Dynamic Host Configuration Protocol (DHCP).
The DHCP server, which usually runs on the router, automatically provides each connected device with an IP address and other important network settings. These settings include the default gateway, which allows devices to access other networks, and one or more Domain Name System (DNS) server addresses, which convert website names into IP addresses.
When a device joins the network, it sends a DHCP request to the DHCP server. The server then assigns the required network configuration. Once these settings are applied, the device can communicate with other devices on the LAN and access Internet services without requiring manual configuration.
Protocols
A network protocol is a set of rules that defines how data is transmitted and received between devices on a network.
Earlier Local Area Networks commonly used protocols such as NetBIOS, IPX/SPX, and AppleTalk for communication between computers. However, these protocols have largely been replaced by the Transmission Control Protocol/Internet Protocol (TCP/IP) suite.
Today, TCP/IP is the standard protocol used in almost all Local Area Networks as well as on the Internet. It enables reliable communication between devices, supports data transmission across different types of networks, and allows computers worldwide to exchange information efficiently.
Connection to Other LANs
A Local Area Network can be connected to another LAN to allow users at different locations to share data, applications, and network resources. These connections can be established through leased communication lines, leased network services, or secure Internet connections using Virtual Private Network (VPN) technology.
Depending on the geographical distance and the type of communication link used, interconnected LANs may be classified as a Metropolitan Area Network (MAN), which covers a city or metropolitan region, or a Wide Area Network (WAN), which covers much larger geographical areas such as multiple cities, countries, or continents.
Connection to the Internet
A Local Area Network can connect to the Internet using various communication technologies, including DSL, ADSL, VDSL, VDSL2, coaxial cable, fiber-optic connections, cellular networks, or satellite communication. The choice of technology depends on the availability of Internet services and the required network speed.
The Internet connection is provided by an Internet Service Provider (ISP), which assigns a public IP address to the network. A router receives this public IP address through its Wide Area Network (WAN) interface and shares the Internet connection with all devices on the Local Area Network using Network Address Translation (NAT). NAT enables multiple devices within the LAN to access the Internet using a single public IP address.
A gateway provides the connection between the local network and the ISP’s communication infrastructure. Modern home and office networking devices often combine several functions into a single unit, including a modem, router, wireless access point, and a multi-port Ethernet switch. This makes network installation simpler and reduces the need for multiple separate devices.
Technologies such as ITU-T G.hn and the IEEE Powerline standard allow high-speed Local Area Networking through existing electrical wiring in a building. These technologies can provide data transfer speeds of up to 1 Gbit/s and are widely used for home networking and IPTV services without requiring additional network cables.