What is LAN (Local Area Network)?
A Local Area Network, or LAN, is a network of computers and other electronic devices in one physical location such as a school, home, or small office. A LAN could contain just a small number of devices or thousands of devices. The defining factor is not the size but rather that the devices are all in a single location.
In contrast, Wide Area Networks, or WANs, are computer networks that connect devices spread across a larger geographic area, while the Internet connects computers worldwide. A computer can be part of more than one network and for computer programs to respond differently to requests from different networks. LANs are also different from Metropolitan Area Networks or MANs, which are networks with a network topology covering an entire single city or defined geographic area (e.g., a “metropolitan area.”
For example, a home user may use the file-sharing feature of Windows to share the family photographs stored on their laptop with other computers in the house. That laptop may also connect to a work intranet (which would be an example of a WAN) and the Internet but not allow machines on those networks to access the same files.
What Devices are Part of a Local Area Network?
A LAN can consist of many different types of network devices. Two personal computers connected via Wi-Fi, Bluetooth (both examples of “wireless LANs”), or twisted pair (a “wired LAN”) would be an example of a LAN. Still, these networks can also contain other devices, including:
- Access points
- Cables (e.g., ethernet cables)
- Network Switches
In a home network, a LAN might simply include computers connected to each other. A more complex LAN could consist of computers used as servers for printer sharing and media streaming.
Why are LANs used?
LANs offer a convenient and straightforward way for computers to share resources. Computer users connect to LANs for many reasons, including:
- Internet connection sharing
- Printer sharing
- Streaming media
- File sharing
- Multiplayer games
- Controlling ‘smart’ devices
The Different Types of LANs
There are two different types of LAN: the peer-to-peer LAN and the client/server LAN. A peer-to-peer LAN doesn’t have a central server. Instead, the devices communicate directly, and no one device controls the functioning of the network or access to resources on it. Peer-to-peer LANs are usually relatively small, comprising only a few devices. It’s common for home networks to have this type of configuration.
Client/server LANs have a central server that manages access rights and resources. Client devices can connect to the server via wired or wireless network connections and authenticate before giving access rights. The LAN connecting server may run one or several applications to handle things like media storage and different network traffic forms, such as streaming, printing, shared internet connections, databases, and internal communication tools.
It’s common for businesses to use client/server LANs or WANs, depending on the organization’s size. The extra control and security of a LAN become necessary when the network grows beyond a handful of devices.
The History of LANs
Networking is not a new technology. Colleges and universities developed LANs in the 1960s to connect computers and facilitate research. The Ethernet technology used in wired networks today was developed at Xerox PARC in 1973. It was adopted as the ‘standard’ by the Institute of Electrical and Electronics Engineers (i.e., IEEE) in 1985.
Technology has improved dramatically in the decades since then, thanks to the introduction of wireless communications and faster Ethernet. Modern Gigabit Ethernet standards, for example, are 100x faster than the old 10Mb/s cards and cables that were common in the 80s and are still in use in some areas today.
In the past, setting up LANs was a complex task, requiring some knowledge of networking and systems administration. Today, with new technologies such as Wireless Zero Configuration, users can connect a device to the LAN with a push of a button. Even wired networks are easy to set up, thanks to the wide availability of DHCP, which assigns each computer on the LAN an address without requiring any complex configuration work by network administrators.
Private Network IP Addresses and LANs
Computers on a LAN usually have an IPv4 address that belongs to one of the Internet Engineering Task Force and Internet Assigned Numbers Authority’s ‘Private Network’ ranges. These are:
- 10.0.0.0 through 10.255.255.255
- 172.16.0.0 through 172.31.255.255
- 192.168.0.0 through 192.168.255.255
Unlike most other IP address ranges, these IPs are classed as private and are not routable to the outside world. For example, 126.96.36.199 is the IP address of one of Google’s DNS servers. That address is unique and reserved for Google’s use. The private network IPs are for use inside a LAN only. Multiple networks can re-use those same private IP addresses. Many home user routers, for example, will have the local IP of 192.168.1.254 set as the address for connecting to their admin panel.
In theory, an individual could use other IP addresses for their LAN, but this could cause issues if the public IP address used duplicated one used by a website that a user of the LAN wanted to access, so it is against best practices to do so.
Modern hardware can make use of IPv6, which has many orders of magnitude more IP addresses available, meaning it’s possible for every device in existence to have an IP address without fear of running out of addresses. In practice, it’s common for LANs to use IPv4 instead, simply for backward compatibility with much older devices.
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