Local Area Network
Definition
A Local Area Network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus, or office building. By contrast, a wide area network (WAN) not only covers a larger geographic distance, but also generally involves leased telecommunication circuits or Internet links.
History
The increasing demand and use of computers in universities and research labs in the late 1960s generated the need to provide high-speed interconnections between computer systems. A 1970 report from the Lawrence Radiation Laboratory detailing the growth of their "Octopus" network gave a good indication of the situation.
Architecture
LANs are typically connected to WANs, which connect multiple LANs together. A LAN can be connected to a WAN using a router. This means that a company can connect its LAN to its WAN and then connect that WAN to the Internet. This allows all the computers on the LAN to access the Internet.
Topologies
The main types of network topologies used in LANs include bus, ring, star, tree and mesh.
Bus topology
In a bus network, all nodes are connected to a common medium, known as the bus. This was the layout used in the original Ethernet.
Ring topology
In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction.
Star topology
In a star network, every host is connected to a central hub. In its simplest form, one central hub acts as a conduit to transmit messages.
Tree topology
A tree topology is a variation of the star topology in which the hubs of many star networks are connected to a central hub.
Mesh topology
In a mesh topology, there are at least two nodes with two or more paths between them.
Protocols
A network protocol defines rules and conventions for communication between network devices. Protocols for LANs include Ethernet, Token Ring, and FDDI.
Performance
Issues such as the amount of traffic, network size, and type of network traffic affect LAN performance. Other factors include the type of transmission medium and the cost of data transmission.
LAN Technologies
Several LAN technologies have been developed and used in the past, including Ethernet, Token Ring, and FDDI. Ethernet is the most widely used LAN technology.
Security
Security considerations in LANs include securing the data, managing user access, and keeping the network up and running. This involves both software and hardware technologies.
Wireless LANs
A wireless LAN (WLAN) is a LAN that uses wireless radio signals to connect devices. This allows for a flexible network layout and is cheaper and easier to implement than a wired LAN.