A Local Area Network (LAN) is a computer network that interconnects the nodes within a limited area such as a residence, school, laboratory or office building. Unlike WAN (wide area network) that covers a large geographic distance and may involve leased telecommunications circuits, the media for LANs are locally managed.
Salient features of LAN:
- Ethernet over twisted pair cabling and Wi-Fi are the most common transmission technologies in use in LAN.
- One or more switches implement the LAN.
- The switch can be connected to a router, cable modem or ADSL modem for Internet access.
- Complex LANs are characterized by their use of redundant links with switches using the spanning tree protocol (STP) to prevent loops, their ability to manage differing traffic types via quality of service (QoS), and to segregate traffic with VLANs.
- A LAN can include a wide variety of network devices such as switches, firewalls, routers, load balancers, and sensors.
LANs can maintain connections with other LANs via leased lines, leased services, or the Internet using virtual private network technologies. Depending on how the connections are established and secured in a LAN, and the distance involved, a LAN may also be classified as a metropolitan area network (MAN) or a wide area network (WAN).
A metropolitan area network (MAN) is a computer network larger than a local area network, covering an area of a few city blocks to the area of an entire city, possibly also including the surrounding areas.
- MAN is implemented using the technologies such as Asynchronous Transfer Mode (ATM), Fiber Distributed Data Interface (FDDI) and Switched Multi-megabit Data Service (SMDS).
- Metro-Ethernet, an Ethernet-based technology is being increasingly used in MANs.
- MAN links between local area networks have also been built with wireless links using either microwave, radio, or infra-red laser transmission.
- Most companies rent or lease circuits from common carriers because laying long stretches of cable is expensive.
- Distributed-queue dual-bus (DQDB) refers to the metropolitan area network standard for data communication specified in the IEEE 802.6 standard. With DQDB, networks can extend up to 20 miles (30 km) long and operate at speeds of 34–155 Mbit/s.
A wide area network (WAN) is a telecommunications network or computer network that extends over a large geographical distance. Wide area networks are often established with leased telecommunication circuits.
- Business, education and government entities use wide area networks to relay data among staff, students, clients, buyers, and suppliers from various geographical locations.
- WAN is a computer network spanning regions, countries, or even the world. The Internet may be considered a WAN.
- Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization’s LAN to the Internet.
- WANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive.
- Protocols including Packet over SONET/SDH, MPLS, ATM and Frame Relay are often used by service providers to deliver the links that are used in WANs.
- X.25 was an important early WAN protocol, and is often considered to be the “grandfather” of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.
- Many technologies are available for wide area network links. Examples include circuit switched telephone lines, radio wave transmission, and optic fiber.
- Now the households that are being connected to the Internet with ADSL, Cable, Wimax, 4G or fiber at speeds ranging from 1 Mbit/s to 1 Gbit/s and the connections in the core of a WAN can range from 1 Gbit/s to 100 Gbit/s.
A campus network, campus area network, corporate area network or CAN is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area.
- The networking equipments (switches, routers) and transmission media (optical fiber, copper plant, Cat5 cabling etc.) are almost entirely owned by the campus owner: an enterprise, university, government etc.
- The network connects various buildings within the University campus or a Corporate campus such as Googleplex.
- Campus networks are normally interconnected with high speed Ethernet links operating over optical fiber such as gigabit Ethernet and 10 Gigabit Ethernet.
- The range of CAN is 1 km to 5 km. If two buildings have the same domain and they are connected with a network, then it will be considered as CAN only.
Wikipedia | Network types