Roaming of Wireless LANs

There are 2 definitions for roaming in WLAN:

• Internal Roaming (1): The Mobile Station (MS) moves from one access point (AP) to another AP within a home network because the signal strength is too weak. An authentication server (RADIUS) assumes the re-authentication of MS via 802.1x (e.g. with PEAP). The billing of QoS is in the home network.

• External Roaming (2): The MS(client) moves into a WLAN of an another Wireless Service Provider (WSP) and takes their services (Hotspot). The user can independently of his home network use another foreign network, if this is open for visitors. There must be special authentication and billing systems for mobile services in a foreign network.^[8].

Roaming between Wireless Local Area Networks

This article from : http://en.wikipedia.org/wiki/Wireless_LAN

Types of wireless LANs

Peer-to-peer

Peer-to-Peer or ad-hoc wireless LAN

An ad-hoc network is a network where stations communicate only peer to peer (P2P). There is no base and no one gives permission to talk. This is accomplished using the Independent Basic Service Set (IBSS).

A peer-to-peer (P2P) allows wireless devices to directly communicate with each other. Wireless devices within range of each other can discover and communicate directly without involving central access points. This method is typically used by two computers so that they can connect to each other to form a network.

If a signal strength meter is used in this situation, it may not read the strength accurately and can be misleading, because it registers the strength of the strongest signal, which may be the closest computer.

802.11 specs define the physical layer (PHY) and MAC (Media Access Control) layers. However, unlike most other IEEE specs, 802.11 includes three alternative PHY standards: diffuse infrared operating at 1 Mbit/s in; frequency-hopping spread spectrum operating at 1 Mbit/s or 2 Mbit/s; and direct-sequence spread spectrum operating at 1 Mbit/s or 2 Mbit/s. A single 802.11 MAC standard is based on CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance). The 802.11 specification includes provisions designed to minimize collisions. Because two mobile units may both be in range of a common access point, but not in range of each other. The 802.11 has two basic modes of operation: Ad hoc mode enables peer-to-peer transmission between mobile units. Infrastructure mode in which mobile units communicate through an access point that serves as a bridge to a wired network infrastructure is the more common wireless LAN application the one being covered. Since wireless communication uses a more open medium for communication in comparison to wired LANs, the 802.11 designers also included a shared-key encryption mechanism, called wired equivalent privacy (WEP), or Wi-Fi Protected Access, (WPA, WPA2) to secure wireless computer networks.

Bridge

A bridge can be used to connect networks, typically of different types. A wireless Ethernet bridge allows the connection of devices on a wired Ethernet network to a wireless network. The bridge acts as the connection point to the Wireless LAN.

Wireless distribution system

Main article: Wireless Distribution System

When it is difficult to connect all of the access points in a network by wires, it is also possible to put up access points as repeaters.

This article from : http://en.wikipedia.org/wiki/Wireless_LAN

Architecture of Wireless LANs

Stations

All components that can connect into a wireless medium in a network are referred to as stations.

All stations are equipped with wireless network interface cards (WNICs).

Wireless stations fall into one of two categories: access points, and clients.

Access points (APs) are base stations for the wireless network. They transmit and receive radio frequencies for wireless enabled devices to communicate with.

Wireless clients can be mobile devices such as laptops, personal digital assistants, IP phones, or fixed devices such as desktops and workstations that are equipped with a wireless network interface.

Basic service set

The basic service set (BSS) is a set of all stations that can communicate with each other.

There are two types of BSS: Independent BSS ( also referred to as IBSS ), and infrastructure BSS.

Every BSS has an identification (ID) called the BSSID, which is the MAC address of the access point servicing the BSS.

An independent BSS (IBSS) is an ad-hoc network that contains no access points, which means they can not connect to any other basic service set.

An infrastructure BSS can communicate with other stations not in the same basic service set by communicating through access points.

Extended service set

An extended service set (ESS) is a set of connected BSSes. Access points in an ESS are connected by a distribution system. Each ESS has an ID called the SSID which is a 32-byte (maximum) character string. For example, "linksys" is the default SSID for Linksys routers.

Distribution system

A distribution system (DS) connects access points in an extended service set. The concept of a DS can be to increase network coverage through roaming between cells.

This article from : http://en.wikipedia.org/wiki/Wireless_LAN

Disadvantages of Wireless LANs

Wireless LAN technology, while replete with the conveniences and advantages described above, has its share of downfalls. For a given networking situation, wireless LANs may not be desirable for a number of reasons. Most of these have to do with the inherent limitations of the technology.

• Security: Wireless LAN transceivers are designed to serve computers throughout a structure with uninterrupted service using radio frequencies. Because of space and cost, the antennas typically present on wireless networking cards in the end computers are generally relatively poor. In order to properly receive signals using such limited antennas throughout even a modest area, the wireless LAN transceiver utilizes a fairly considerable amount of power. What this means is that not only can the wireless packets be intercepted by a nearby adversary's poorly-equipped computer, but more importantly, a user willing to spend a small amount of money on a good quality antenna can pick up packets at a remarkable distance; perhaps hundreds of times the radius as the typical user. In fact, there are even computer users dedicated to locating and sometimes even cracking into wireless networks, known as wardrivers. On a wired network, any adversary would first have to overcome the physical limitation of tapping into the actual wires, but this is not an issue with wireless packets. To combat this consideration, wireless networks users usually choose to utilize various encryption technologies available such as Wi-Fi Protected Access (WPA). Some of the older encryption methods, such as WEP are known to have weaknesses that a dedicated adversary can compromise. (See main article: Wireless security.)

• Range: The typical range of a common 802.11g network with standard equipment is on the order of tens of metres. While sufficient for a typical home, it will be insufficient in a larger structure. To obtain additional range, repeaters or additional access points will have to be purchased. Costs for these items can add up quickly. Other technologies are in the development phase, however, which feature increased range, hoping to render this disadvantage irrelevant. (See WiMAX)

• Reliability: Like any radio frequency transmission, wireless networking signals are subject to a wide variety of interference, as well as complex propagation effects (such as multipath, or especially in this case Rician fading) that are beyond the control of the network administrator. One of the most insidious problems that can affect the stability and reliability of a wireless LAN is the microwave oven.^[7] In the case of typical networks, modulation is achieved by complicated forms of phase-shift keying (PSK) or quadrature amplitude modulation (QAM), making interference and propagation effects all the more disturbing. As a result, important network resources such as servers are rarely connected wirelessly.

• Speed: The speed on most wireless networks (typically 1-108 Mbit/s) is reasonably slow compared to the slowest common wired networks (100 Mbit/s up to several Gbit/s). There are also performance issues caused by TCP and its built-in congestion avoidance. For most users, however, this observation is irrelevant since the speed bottleneck is not in the wireless routing but rather in the outside network connectivity itself. For example, the maximum ADSL throughput (usually 8 Mbit/s or less) offered by telecommunications companies to general-purpose customers is already far slower than the slowest wireless network to which it is typically connected. That is to say, in most environments, a wireless network running at its slowest speed is still faster than the internet connection serving it in the first place. However, in specialized environments, higher throughput through a wired network might be necessary. Newer standards such as 802.11n are addressing this limitation and will support peak throughputs in the range of 100-200 Mbit/s.

Wireless LANs present a host of issues for network managers. Unauthorized access points, broadcasted SSIDs, unknown stations, and spoofed MAC addresses are just a few of the problems addressed in WLAN troubleshooting. Most network analysis vendors, such as Network Instruments, Network General, and Fluke, offer WLAN troubleshooting tools or functionalities as part of their product line.

This article from : http://en.wikipedia.org/wiki/Wireless_LAN

Benefits of Wireless LANs

The popularity of wireless LANs is a testament primarily to their convenience, cost efficiency, and ease of integration with other networks and network components. The majority of computers sold to consumers today come pre-equipped with all necessary wireless LAN technology.

These are the benefits of wireless LANs:

• Convenience: The wireless nature of such networks allows users to access network resources from nearly any convenient location within their primary networking environment (home or office). With the increasing saturation of laptop-style computers, this is particularly relevant.

• Mobility: With the emergence of public wireless networks, users can access the internet even outside their normal work environment. Most chain coffee shops, for example, offer their customers a wireless connection to the internet at little or no cost.

• Productivity: Users connected to a wireless network can maintain a nearly constant affiliation with their desired network as they move from place to place. For a business, this implies that an employee can potentially be more productive as his or her work can be accomplished from any convenient location.

• Deployment: Initial setup of an infrastructure-based wireless network requires little more than a single access point. Wired networks, on the other hand, have the additional cost and complexity of actual physical cables being run to numerous locations (which can even be impossible for hard-to-reach locations within a building).

• Expandability: Wireless networks can serve a suddenly-increased number of clients with the existing equipment. In a wired network, additional clients would require additional wiring.

• Cost: Wireless networking hardware is at worst a modest increase from wired counterparts. This potentially increased cost is almost always more than outweighed by the savings in cost and labor associated to running physical cables.

This article from : http://en.wikipedia.org/wiki/Wireless_LAN

History of Wireless LAN

In 1970 University of Hawaii, under the leadership of Norman Abramson, developed the world’s first computer communication network using low-cost ham-like radios, named ALOHAnet. The bi-directional star topology of the system included seven computers deployed over four islands to communicate with the central computer on the Oahu Island without using phone lines.^[3]

"In 1979, F.R. Gfeller and U. Bapst published a paper in the IEEE Proceedings reporting an experimental wireless local area network using diffused infrared communications. Shortly thereafter, in 1980, P. Ferrert reported on an experimental application of a single code spread spectrum radio for wireless terminal communications in the IEEE National Telecommunications Conference. In 1984, a comparison between Infrared and CDMA spread spectrum communications for wireless office information networks was published by Kaveh Pahlavan in IEEE Computer Networking Symposium which appeared later in the IEEE Communication Society Magazine. In May 1985, the efforts of Marcus led the FCC to announce experimental ISM bands for commercial application of spread spectrum technology. Later on, M. Kavehrad reported on an experimental wireless PBX system using code division multiple access. These efforts prompted significant industrial activities in the development of a new generation of wireless local area networks and it updated several old discussions in the portable and mobile radio industry.

The first generation of wireless data modems was developed in the early 1980s by amateur radio operators, who commonly referred to this as packet radio. They added a voice band data communication modem, with data rates below 9600 bit/s, to an existing short distance radio system, typically in the two meter amateur band. The second generation of wireless modems was developed immediately after the FCC announcement in the experimental bands for non-military use of the spread spectrum technology. These modems provided data rates on the order of hundreds of kbit/s. The third generation of wireless modem [then] aimed at compatibility with the existing LANs with data rates on the order of Mbit/s. Several companies [developed] the third generation products with data rates above 1 Mbit/s and a couple of products [had] already been announced [by the time of the first IEEE Workshop on Wireless LANs]."^[4]

"The first of the IEEE Workshops on Wireless LAN was held in 1991. At that time early wireless LAN products had just appeared in the market and the IEEE 802.11 committee had just started its activities to develop a standard for wireless LANs. The focus of that first workshop was evaluation of the alternative technologies. [By 1996], the technology [was] relatively mature, a variety of applications [had] been identified and addressed and technologies that enable these applications [were] well understood. Chip sets aimed at wireless LAN implementations and applications, a key enabling technology for rapid market growth, [were] emerging in the market. Wireless LANs [were being] used in hospitals, stock exchanges, and other in building and campus settings for nomadic access, point-to-point LAN bridges, ad-hoc networking, and even larger applications through internetworking. The IEEE 802.11 standard and variants and alternatives, such as the wireless LAN interoperability forum and the European HiperLAN specification had made rapid progress, and the unlicensed PCS [ Unlicensed Personal Communications Services and the proposed SUPERNet, later on renamed as U-NII, bands also presented new opportunities." ^[5]

On July 21, 1999, AirPort debuted at the Macworld Expo in New York City with Steve Jobs picking up an iBook supposedly to give the cameraman a better shot as he surfed the Web. Applause quickly built as people realized there were no wires. This was the first time Wireless LAN became publicly available at consumer pricing and easily available for home use.^{[citation needed]} Before the release of the Airport, Wireless LAN was too expensive for consumer use and used exclusively in large corporate settings.^{[citation needed]}

Originally WLAN hardware was so expensive that it was only used as an alternative to cabled LAN in places where cabling was difficult or impossible. Early development included industry-specific solutions and proprietary protocols, but at the end of the 1990s these were replaced by standards, primarily the various versions of IEEE 802.11 (Wi-Fi). An alternative ATM-like 5 GHz standardized technology, HiperLAN/2, has so far not succeeded in the market, and with the release of the faster 54 Mbit/s 802.11a (5 GHz) and 802.11g (2.4 GHz) standards, almost certainly never will.

In November 2007, the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) won a legal battle in the US federal court of Texas against Buffalo Technology which found the US manufacturer had failed to pay royalties on a US WLAN patent CSIRO had filed in 1996. CSIRO are currently engaged in legal cases with computer companies including Microsoft, Intel, Dell, Hewlett-Packard and Netgear which argue that the patent is invalid and should negate any royalties paid to CSIRO for WLAN-based products.

This article from : http://en.wikipedia.org/wiki/Wireless_LAN

Wireless LAN

A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers or devices without using wires. WLAN uses spread-spectrum or OFDM modulation technology based on radio waves to enable communication between devices in a limited area, also known as the basic service set. This gives users the mobility to move around within a broad coverage area and still be connected to the network.

For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops. Public businesses such as coffee shops or malls have begun to offer wireless access to their customers; some are even provided as a free service. Large wireless network projects are being put up in many major cities. Google is even providing a free service to Mountain View, California^[1] and has entered a bid to do the same for San Francisco.^[2] New York City has also begun a pilot program to cover all five boroughs of the city with wireless Internet access.

This article from : http://en.wikipedia.org/wiki/Wireless_LAN

LAN Party Equipment

Patrons

The sort of equipment someone would take to a LAN party, be it a small or large one, includes:

Hardware

• Computer
• Monitor
• Keyboard
• Mouse and mouse pad
• Headphones/Speakers (Usually Headphones as it is common for organizers of larger LAN parties to disallow the use of speakers as it distracts other party goers)
• Microphone
• Power cables for monitor and computer
• Surge Protector (A power strip will suffice if a Surge Protector is not available, but doesn't afford the same level of protection against spikes and fluctuations in power.)
• Network cables
• Network hub or switch

Software

• Games with their respective CD keys and latest patches.
• Device Drivers for your hardware.

Host

The host's job in a LAN party involves much more work, especially in large parties:

• Power. Most hosts should allow for about 350-400 watts of power per attendant on average, with approximately 80% utilization per circuit. (E.g., in North America, this would be five to six people on a typical 20A Circuit.)
• Networking. Ethernet networks are almost universally used. In large parties, a common configuration scheme is a Gigabit Ethernet backbone switch, and a high-speed internet router and Fast Ethernet switches connected to that. Servers for basic network services (DHCP,DNS,Proxy server, etc.). In smaller parties, the host's existing network will often do.
• Space. Computer monitors, keyboards, and mouse area take up a significant amount of space. Hosts should see to it there is enough room available for the number of people planning to attend.
• Cooling. Running a number of computers and monitors together in a room can raise heat issues that may not just affect comfort but the computers themselves. This is usually not an issue in larger venues, but may be neglected in a home setting until it's too late.
• Information services. LAN parties of some size often have a video projector to distribute important information, and a stage of some sort to announce competition winners. Bigger LAN parties may also have internal net radio, internal web sites, and even an internal IP based television channel.
• Planning. Nothing is worse for patrons than showing up to an empty LAN party, or finding out that few people are going to the current one.

Culture

LAN parties have their own unique culture. Attendees often show off their computers with flashy aftermarket lighting, plasma screens, enhanced speakers, and many other types of computer accessories (otherwise known as Case modding).^[9] Highly caffeinated drinks, termed energy drinks, are very popular in these events to improve concentration and stamina as LAN parties often run into the early morning hours.^[10] Large parties can last for several days with no scheduled breaks. Often sleep is compromised to play throughout the night and into the next day.

Gaming console system links

Another type of LAN Party is a gaming console System Link. It can range from a small group of friends linking at least two consoles with LAN capabilities (such as the Xbox or Xbox 360) together with a Cat 5 crossover cable, to a separate part of a bigger, established LAN Party. At these, many people connect their consoles to an existing LAN Network already available using a standard Cat 5 cable. Most consoles are capable of networks between as many as 32 units. It is becoming more common for different consoles to be present at larger LAN events giving a massive array of different games, on different formats available to play. This functionality is similar to Sega's DirectLink for Sega Saturn.

This article from : http://en.wikipedia.org/wiki/LAN_party

Larger LAN parties

Many commercialized parties offer various tournaments, with competitions in such games as StarCraft, Quake III, Call of Duty 2, Warcraft III, Counter-Strike, Unreal Tournament, America's Army, Battlefield 2, Doom series, and the Halo Series sometimes awarding prizes to the winners. Prizes can include computer hardware such as overclocking kits, cases, lights, fans, graphic cards and sometimes even complete computers (often considered humorous as typically the winner of the competition would already have (and be competing on) a custom PC far superior to the prize).

The duration of the event is not standardized; many organized parties last for a weekend, while there have also been longer and shorter parties such as weekend wars.

Big LAN parties often offer a quiet place to sleep, shower, and eat, as well as hired security, alternative entertainment (such as music), and a dedicated support crew, as well as a professionally managed network including a connection to the Internet. Catering might come in the form of a bar, delivered food such as pizza, or nearby shops. Some parties come fully catered in the form of regular barbecues or even employment of a catering staff running a public canteen.

Gaming clans -- groups of gamers that often play in team games -- often use these gatherings to meet one another, since they typically play together over the Internet between other parties with little real-world contact. Their goal is often to win tournaments. Clans are often in "ladders" where they move up after winning a match. As well as counting for standings in national and international gaming leagues such as the CPL there are regular events such as QuakeCon in which the very best players from around the world compete against one another, much like in popular sports. Practice matches are usually held prior to a match so competitors can get a rough idea of what they are up against.

Often case modders and overclockers attend these events to display their computers, which otherwise would be seen by few. Some come just to display their computers and look at others' computers.

Some attendees also use these parties for the purpose of file sharing. Copyright infringement via file sharing is often discouraged or forbidden by the larger parties. However, enforcement is rare and spotty due to the time involved and often a lack of desire by organizers. Some LAN parties actively support file sharing for legitimate purposes (game patches, updates, user contributed content), and may run Direct Connect hubs or other P2P service servers. One of the main reasons for running such servers is so file sharing can be monitored/controlled while standard Windows file sharing (SMB/CIFS) can be blocked, thus preventing the spread of SMB/CIFS-based viruses. Most P2P setups used at LAN parties also have a 'centralized' chat area, where all members of the LAN party can converse in an IRC-like environment.

There are also other kinds of parties not referred to as "LAN parties" where temporary LANs are built, but are not used as a main attraction. Amongst these are demoparties such as Assembly and hacker conventions such as DEF CON.

In the traditionally active demoscene countries, such as those in Northern Europe, the LAN party culture is often heavily influenced by demoparties. This is due to the fact that many of the largest demoparties were already well established in the early 1990s and their facilities were also suitable for large-scale LAN party activity. This eventually led gaming clans and other similar groups to attend these events and regard them merely as large LAN parties. On the other hand, it is not uncommon for "pure" LAN parties in Northern Europe to organize some demoscene-like competitions in areas such as computer graphics or home videos.

This article from : http://en.wikipedia.org/wiki/LAN_party

Small LAN parties

Usually smaller LAN parties consist of people bringing their computers over to each others' houses to host and play multiplayer games.

These are sometimes established between small groups of friends, and hosted at a central location or one that is known to all participants. Such events are often organized quickly with little planning, and some overnight events, with some stretching into days (or even weeks). Because of the small number of players, games are usually played on small levels and/or against bots. When a broadband Internet connection is available, some LAN parties will join on-line servers, where all computers connect to the same server to play together, often on the same team. In this case, the LAN party helps bring the team in one physical location, to communicate to teammates more efficiently.

A small LAN party requires a hub/switch, with enough ports to accommodate all the players, a fair amount of power, and suitable surfaces for all the computers. Providing refreshments is often also a duty of the host, though guests are usually asked to contribute. In larger parties where participants may not all know each other personally, an entry fee may even be charged. Another tradition of some small groups is to purchase large amounts of fast food for consumption over many days. Many LAN participants will also bring energy drinks and other food to consume over the course of the party.

To set up these parties a network hub/switch isn't always required. If all the computers have Wi-Fi capability, an ad-hoc network may be set up. This allows two or more computers to connect over a wireless connection, thereby eliminating the need for a wired network.

When some of the participants cannot be present or when merging a few LAN parties together, VPN software such as Remobo or Hamachi can be used to arrange computers over the Internet so they appear to be on the same LAN.

This article from : http://en.wikipedia.org/wiki/LAN_party

History of LAN Party

LAN parties originated from early single-player Unix games such as Larn, Hack, Rogue, and Hunt the Wumpus that kept scoreboards on a centralized server.^[4] At this point the majority of the people playing these games were university students who had access to such systems for schoolwork. Another early incarnation of network gaming was Xanth Software F/X's MIDI Maze. Programmed for the Atari ST, the game allowed up to 16 computers (though any number above four caused instability) to be linked together via the ST's MIDI ports and deathmatch games to be played over the makeshift network. With the release of Bungie's Pathways Into Darkness and id Software's Doom in 1993, the gameplay that MIDI Maze pioneered was perfected, with the latter allowing four players either to cooperate in the game's singleplayer campaign or to fight each other in a deathmatch game. As a result, network gaming (and consequently LAN parties) grew. The initial explosion for the LAN Party scene occurred with the release of Bungie's Marathon on the easily-networked Macintosh platform in 1994. By the time Id Software's Quake was released in 1996, the release of Windows 95 and many low-cost Ethernet cards had brought relatively easy ad-hoc networking to the Windows PC, further expanding the popularity of LAN Parties.

This article from : http://en.wikipedia.org/wiki/LAN_party

LAN Party ???

A LAN party is a temporary, sometimes spontaneous, gathering of people together with their computers, which they network together primarily for the purpose of playing multiplayer computer games. These local area networks (LANs) come in various sizes, from very small (two people) to very large (more than 10,000 people). Small parties can form spontaneously, but large ones usually require a fair amount of planning and preparation on the part of the organizer. The current world record for number of computers connected in the network at a LAN party is 10,445, set at DreamHack Winter 2007, in Jönköping, Sweden.^[1]. The current world record for the longest continuous LAN party is 36 hours, held by the NVISION 08 LAN party in August 2008 in San Jose, CA^[2].

LAN party events differ significantly from gaming centers and Internet cafes in that they are generally bring your own computer (BYOC)^[3] and are not permanent installations, often taking place in general meeting places or residences.

LAN party attendees tend to be more experienced gamers, as the setup required turns most casual gamers away.

This article from : http://en.wikipedia.org/wiki/LAN_party

LAN messenger

A LAN messenger is an instant messaging program designed for use within a single local area network (LAN).

The first LAN messenger for Microsoft Windows is Winpopup, a small utility included in Windows 3.11/95/98/Me intended to receive and send short instant text messages. Winpopup uses SMB/NetBIOS protocol.

Windows NT/2000/XP improves upon this with Messenger service, a Windows service for receiving and sending messages compatible to WinPopup. On systems where this service is running, the received messages "pop up" as simple message boxes. Any software compatible with winpopup, like the console utility NET SEND, can send such messages.

By default, Messenger service is off in Windows XP SP2 and blocked by Windows XP's firewall.

Many alternatives for MS winpopup and NET SEND use proprietary TCP/IP protocols.

Objectives

The objectives of LAN messenger are as following:

Increase productivity: By design, the system does not allow users to talk to people outside of the LAN. This will decrease the amount of time people spend talking to outsiders on non-work related issues using public messenger systems.

Network security: The program runs inside the company LAN, so only people who are inside the firewall will have access to the system. The system cannot be spammed from the outside. The data does not leave the LAN so it cannot be snooped by outsiders.

Decrease cost: The LAN Messenger System will help the organization to decrease their cost on phone bills and internet bills.

Secured: Common means of communication, such as verbal instructions, phone conversations and e-mail messaging, are far from perfection when it comes to delivering short messages to multiple individuals. Internet-based instant messaging solutions are good but they rely on third-party services which makes the entire system unreliable in question. The best solution shall be a messenger system working in local network. Quick communication: LAN Messenger System allows quick and fast communication among the users of the system in the organization. There no need to make phone calls, send e-mails or fax.

Highly efficient: Traditional ways to spread information throughout an organization are through meetings, memos, newsletters, and the postal system. Using the LAN Messenger System, all these information can be sent via chat

This article from : http://en.wikipedia.org/wiki/LAN_messenger

Technical aspects (LAN)

Although switched Ethernet is now the most common data link layer protocol and IP as a network layer protocol, many different options have been used, and some continue to be popular in niche areas. Smaller LANs generally consist of a one or more switches linked to each other - often with one connected to a router, cable modem, or DSL modem for Internet access.

Larger LANs are characterized by their use of redundant links with switches using the spanning tree protocol to prevent loops, their ability to manage differing traffic types via quality of service (QoS), and to segregate traffic via VLANs. Larger LANS also contain a wide variety of network devices such as switches, firewalls, routers, load balancers, sensors and so on.^[9]

LANs may have connections with other LANs via leased lines, leased services, or by 'tunneling' across the Internet using VPN technologies. Depending on how the connections are made, secured, and the distance involved they become a Metropolitan Area Network (MAN), a Wide Area Network (WAN), or a part of the internet.

This article from : http://en.wikipedia.org/wiki/Local_area_network

History LAN

As larger universities and research labs obtained more computers during the late 1960s, there was increasing pressure to provide high-speed interconnections. A report in 1970 from the Lawrence Radiation Laboratory detailing the growth of their "Octopus" network^[1][2], gives a good indication of the situation.

Early systems

Cambridge University's Cambridge Ring was started in 1974^[3] but was never developed into a successful commercial product.

Ethernet was developed at Xerox PARC in 1973–1975,^[4] and filed as U.S. Patent 4,063,220 . In 1976, after the system was deployed at PARC, Metcalfe and Boggs published their seminal paper - "Ethernet: Distributed Packet-Switching For Local Computer Networks"^[5]

ARCNET was developed by Datapoint Corporation in 1976 and announced in 1977 ^[6] - and had the first commercial installation in December 1977 at Chase Manhattan Bank in New York^[7]

The Personal Computer

The development and proliferation of CP/M-based personal computers from the late 1970s and then DOS-based personal computers a from 1981 meant that a single site began to have dozens or even hundreds of computers. The initial attraction of networking these was generally to share disk space and laser printers, which were both very expensive at the time. There was much enthusiasm for the concept and for several years, from about 1983 onward, computer industry pundits would regularly declare the coming year to be “the year of the LAN”.

In reality, the concept was marred by proliferation of incompatible physical layer and network protocol implementations, and confusion over how best to share resources. Typically, each vendor would have its own type of network card, cabling, protocol, and network operating system. A solution appeared with the advent of Novell NetWare which provided even-handed support for the 40 or so competing card/cable types, and a much more sophisticated operating system than most of its competitors. Netware dominated^[8] the personal computer LAN business from early after its introduction in 1983 until the mid 1990s when Microsoft introduced Windows NT Advanced Server and Windows for Workgroups.

Of the competitors to NetWare, only Banyan Vines had comparable technical strengths, but Banyan never gained a secure base. Microsoft and 3Com worked together to create a simple network operating system which formed the base of 3Com's 3+Share, Microsoft's LAN Manager and IBM's LAN Server. None of these were particularly successful.

In this same timeframe, Unix computer workstations from vendors such as Sun Microsystems, Hewlett-Packard, Silicon Graphics, Intergraph, NeXT and Apollo were using TCP/IP based networking. Although this market segment is now much reduced, the technologies developed in this area continue to be influential on the Internet and in both Linux and Apple Mac OS X networking—and the TCP/IP protocol has now almost completely replaced IPX, AppleTalk, NBF and other protocols used by the early PC LANs.

Cabling

Early LAN cabling had always been based on various grades of co-axial cable, but IBM's Token Ring used shielded twisted pair cabling of their own design, and in 1984 StarLAN showed the potential of simple Cat3 unshielded twisted pair—the same simple cable used for telephone systems. This led to the development of 10Base-T (and it's successors) and structured cabling which is still the basis of most LANs today.

This article from :http://en.wikipedia.org/wiki/Local_area_network

LAN >> Local Area Network ???

"LAN" redirects here. For other uses, see LAN (disambiguation).

A 'area network' is a computer network covering a small geographic area, like a home, office, or group of buildings e.g. a school. The defining characteristics of LANs, in contrast to wide-area networks (WANs), include their much higher data-transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines.

Ethernet over unshielded twisted pair cabling, and Wi-Fi are the two most common technologies currently, but ARCNET, Token Ring and many others have been used in the past.

This article from : http://en.wikipedia.org/wiki/Local_area_network