A local area network (LAN) is a computer network that connects computers in limited areas such as school, home, computer lab, or office buildings. [1] The defining characteristics of LANs, in contrast to the wide area network (WAN), including their usually higher data transfer rates, smaller geographic areas, and lack of need for leased telecommunication networks.
ARCnet, Token Ring and other technology standards have been used in the past, but Ethernet over twisted pair cabling, and Wi-Fi are the two most common technologies currently used to build the LAN.
Early LAN cabling is always based on the various classes of coaxial cable. However, shielded twisted pair is used in the IBM Token Ring implementation, and in 1984 showed the potential of a simple StarLAN unshielded twisted pair Cat3-using the same simple cable used for telephone systems. This led to the development of 10Base-T (and successors) and structured cabling is still the basis of most current commercial LAN. In addition, fiber optic cable is increasingly used in commercial applications.
Because this cable is not always possible, wireless Wi-Fi is now the most common technology in the residence, because the cable required is minimal and is perfect for mobile laptop and smartphone.
Today, most LAN technology based on IEEE 802.3 Ethernet switch using the device, which has a data transfer speed 10, 100, or 1000 Mbit / s. In addition to Ethernet technology, the current 802.11b technology (or so-called Wi-Fi) is also often used to form the LAN. Places that provide LAN connectivity with Wi-Fi technology called hotspots.
On a LAN, each node or computer has its own computing power, in contrast to the concept of terminal dump. Each computer can also access resources on the LAN in accordance with the permissions that have been set. These resources can be data or devices such as printers. On a LAN, a user can also communicate with other users by using the appropriate application.
There are different types of LANs Ethernets are most common for PCs. Most Apple Macintosh networks are based on Apple's AppleTalk network system, which is built into Macintosh computers.
Following characteristics differentiate one LAN from another:
a. Topology: The composition of geometric devices on a network. For example, the device can be arranged in a ring or in a straight line.
b. Protocols: The rules and encoding specifications for sending data. The protocol also determines whether the network using peer-to-peer or client / server architecture.
c. Media: Devices can be connected by twisted-pair cable, coaxial cable, or fiber optic cables. A number of networks without connecting media altogether, communicating instead via radio waves
2. Wan (Wide Area Network)
WAN covers a wide geographical area, such as a province, state or country. WANs often connect multiple smaller networks, such as local area networks (LANs) or metro area network (MAN).
WAN in the world's most popular is the Internet. Some segments of the Internet, such as VPN-based extranet, WAN also within them. Finally, many companies or research WAN networks using leased lines.
WAN network equipment generally use a different and far more expensive than the LAN. Key technologies often found in WANs include SONET, Frame Relay, and ATM
Wide Area Network consists of dark fiber and active communications equipment. Among these are network switches, optical multiplexers and media converters. The WAN will be implemented using 10 Gigabit Ethernet (GbE 10) technology. This is an obvious choice for distances up to ~ 40 km with a pair of transmitter / single receiver, but will also be used for longer distances but cheap and reliable alternatives are available (eg by reuse of existing infrastructure).
Network formed often by seeking the help of telecomm departments that provide leased line facilities. The router is connected to the LAN on one side and a hub mounted at the other end. This is an expensive way to form a WAN (Wide Area Network) networks. WAN (Wide Area Network) networks are often formed using the method of circuit switching. A circuit switching network is established when at the end of one node and at the other end of the terminal is physically connected to each other for further communication. Network nodes is the most common physical switches, hubs and modems. While the terminal is a physical device that perform basic communication, such as telephone, answering machine or printer sometimes. Data moves through the use of network protocols. A protocol is a set of rules that guide the transfer of information. The purpose of the protocol is to detect errors.
WAN devices :
a. WAN Switch
A WAN switch is a multiport internetworking device used in carrier networks. These devices typically switch traffic such as Frame Relay, X.25, and SMDS and operate at the data link layer of the OSI reference model.
b. Access Server
An access server acts as a concentration point for dial-in and dial-out connections.
c. Modem
Modem is a device that interprets digital and analog signals, allowing data to be transmitted over voice-grade telephone lines.
d. CSU / DSU
A CSU / DSU (channel service unit / digital service unit) is a digital-interface device that adapts the physical interface on the device (Data Terminal Equipment) interface from the DCE that the DTE (Data Circuit-Terminating)-enabled devices in the network operator. CSU / DSU also provides signal timing for communication between devices.
e. ISDN Terminal Adapter
An ISDN terminal adapter is a device used to connect ISDN Basic Rate Interface (BRI) connections to other interfaces, such as EIA/TIA-232. A terminal adapter is essentially an ISDN modem.
How to Work a WAN ..??
If we develop a virtual network switching or packet switching network, we often need to relay the frame to transfer the data in (Wide Area Network) WAN. Frame data packets are transferred from one end to the other. There are many types of WAN (Wide Area Network) protocols such as TCP / IP, MPLS, frame relay and ATM. Most (Wide Area Network) WAN using the X.25 protocol, but is well-known WAN is used to transfer packets. X.25 packet switching was established by the exchange, which is a physical node at one end and leased telephone lines at the other end.
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