Wi-Fi networks use radio technologiesdefined by IEEE 802.11b, 802.11a, 802.11g or 802.11n (and 802.11y) . A Wi-Fi network can be used to connect computers to each other, to the Internet, and to wired networks using IEEE 802.3 or Ethernet. Wi-Fi networks operate in the unlicensed 2.4 and 5 GHz radio bands, with an 11 Mbps (802.11b) or 54 Mbps (802.11a or 802.11g) data rate or with products that contain both bands (dual band), so they can provide real-world performance similar to the basic 10BaseT wired Ethernet networks used in many offices. Unfortunately, 802.11a is not compatible with 802.11b/g.
Wi-Fi is a standard developed by the Wi-Fi Alliance who certifies vendor products to ensure 802.11 products on the market follow the various 802.11 specifications.
Wireless LANs are not sufficiently protected. It is vulnerable to virus attacks and information privacy invasion. Security technologies are developed to enhance the WLAN security, including, Wired Equivalent Privacy (WEP), Wireless Application Protocol (mainly for mobile devices) plus many vendor proprietary technologies.
The following components are required in a typical Wi-Fi wireless LAN: a WLAN card that is installed into a PC or other devices and an Access Point connected with the LAN that communicates with the WLAN enabled PC and other devices wirelessly.
The current Wi-Fi Standards:
IEEE 802.11 - The original WLAN standard (1997)
IEEE 802.11a – Enhancement to 802.11 with 54 Mbit/s at 5 GHz (1999)
IEEE 802.11b - Enhancements to 802.11 to support 5.5 and 11 Mbit/s (1999)
IEEE 802.11c - Bridge operation procedures; included in the IEEE 802.1D standard (2001)
IEEE 802.11d - International (country-to-country) roaming extensions (2001)
IEEE 802.11e - Enhancements: QOS, including packet bursting (2005)
IEEE 802.11f - Inter-Access Point Protocol (2003) Withdrawn February 2006
IEEE 802.11g – Enhancement to 802.11b and 802.11a (backwards compatible with b) (2003)
IEEE 802.11h - Spectrum Managed 802.11a (5 GHz) for European compatibility (2004)
IEEE 802.11i - Enhanced security (2004)
IEEE 802.11j - Extensions for Japan (2004)
IEEE 802.11-2007 - A release of the standard that includes 802.11 amendments a, b, d, e, g, h, i & j. (2007)
IEEE 802.11k - Radio resource measurement enhancements
IEEE 802.11m - Maintenance of the standard; odds and ends.
IEEE 802.11n – Enhancement to 802.11a,b,g with Higher throughput improvements using MIMO
IEEE 802.11p - WAVE - Wireless Access for the Vehicular Environment (such as ambulances and passenger cars)
IEEE 802.11r - Fast roaming
IEEE 802.11s - ESS Extended Service Set Mesh Networking
IEEE 802.11t - Wireless Performance Prediction (WPP) - test methods and metrics recommendation
IEEE 802.11u - Interworking with non-802 networks (for example, cellular)
IEEE 802.11v - Wireless network management
IEEE 802.11w - Protected Management Frames
IEEE 802.11y - 3650-3700 Operation in the U.S.
IEEE 802.11z - Extensions to Direct Link Setup (DLS)
Tuesday, March 3, 2009
Wi-Fi Wireless LAN (WLAN) Networking Architecture and Technologies
Wireless local area networks (WLANs), based on the WiFi technologies are often implemented as an overlay to the wired LAN based on the Ethernet technology. There are two main architectures used in the WLAN environment:
Peer-to-peer autonomous architecture in which the wireless access point (AP) has autonomy over access, security, and operation. APs in this architecture usually do not require a wireless controller.
Centralized WLAN architecture in which Lightweight APs with limited functionality are used, with most of the wireless intelligence residing at a central controlling device (i.e., the WLAN controller).
One can certainly combine the above two architectures to form a mixed environment to achieve its purpose.
The choice of WLAN architecture will come after considering factors such as network size, migration, and costs.
Network size - Distributed WLAN with autonomous APs can become difficult to manage if deployed in large numbers. There are no defined rules as to how large a deployment must be before it can be considered too large to manage. As a basic rule of thumb, if more than 5 to 10 APs are deployed, a centralized solution can potentially be more cost-effective than a distributed autonomous architecture. A centralized architecture could translate into lower operational costs because network policies, security settings, and radio-frequency power settings can be managed from a single device.
Migration- If a small wireless deployment requires only a few APs, the WLAN can be designed using distributed autonomous APs. As wireless coverage is expanded with the addition of APs, the solution can be converted into a centralized lightweight architecture. Migration from an autonomous to a lightweight solution is possible with the addition of the wireless controller and an operating system upgrade to selected APs from certain equipment providers.
Costs- Normally, the hardware cost of a lightweight AP is lower than that of an autonomous AP, but the cost of the wireless controller must be factored into the total cost. In addition to the capital cost of device purchases, the cost of managing the network should also be accounted in the equation.
Wi-Fi WLAN Networking Architecture
Peer-to-peer autonomous architecture in which the wireless access point (AP) has autonomy over access, security, and operation. APs in this architecture usually do not require a wireless controller.
Centralized WLAN architecture in which Lightweight APs with limited functionality are used, with most of the wireless intelligence residing at a central controlling device (i.e., the WLAN controller).
One can certainly combine the above two architectures to form a mixed environment to achieve its purpose.
The choice of WLAN architecture will come after considering factors such as network size, migration, and costs.
Network size - Distributed WLAN with autonomous APs can become difficult to manage if deployed in large numbers. There are no defined rules as to how large a deployment must be before it can be considered too large to manage. As a basic rule of thumb, if more than 5 to 10 APs are deployed, a centralized solution can potentially be more cost-effective than a distributed autonomous architecture. A centralized architecture could translate into lower operational costs because network policies, security settings, and radio-frequency power settings can be managed from a single device.
Migration- If a small wireless deployment requires only a few APs, the WLAN can be designed using distributed autonomous APs. As wireless coverage is expanded with the addition of APs, the solution can be converted into a centralized lightweight architecture. Migration from an autonomous to a lightweight solution is possible with the addition of the wireless controller and an operating system upgrade to selected APs from certain equipment providers.
Costs- Normally, the hardware cost of a lightweight AP is lower than that of an autonomous AP, but the cost of the wireless controller must be factored into the total cost. In addition to the capital cost of device purchases, the cost of managing the network should also be accounted in the equation.
Wi-Fi WLAN Networking Architecture
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Related Terms:Wi-Fi, Wireless LAN, WLAN, WLAN Architecture, Wi-Fi Technologies
Reference Links:
http://www.javvin.com/wlan-wifi-guide.html: WLAN (Wi-Fi) Quick Guide
http://www.javvin.com/wirelessmap.html : Wireless Communication Technology Map
Hotspots/Wireless LAN Software for WIFI / WMax
Aradial Hotspot radius software server is a top performance full-featured RADIUS server. Boasting excellent performance and technological superiority, Aradial is the unquestioned market leader in its class.
Aradial Radius Hotspot Edition, A special Hotspots/WISP version of our market-leading RADIUS/AAA server, that lets hotspots providers easily and profitably offer wireless Internet access to customers, while eliminating the overhead associated with customer provisioning, authorization and accounting.
Aradial HotSpot Server for wireless includes a RADIUS server that is particularly suited for the security and authentication requirements of wireless based network and easy connectivity module for an existing billing system that allows to update the billing system in real time on customers activities. Aradial allows reporting and easy export of usage to other systems.
Aradial Radius Hotspot Edition, A special Hotspots/WISP version of our market-leading RADIUS/AAA server, that lets hotspots providers easily and profitably offer wireless Internet access to customers, while eliminating the overhead associated with customer provisioning, authorization and accounting.
Aradial HotSpot Server for wireless includes a RADIUS server that is particularly suited for the security and authentication requirements of wireless based network and easy connectivity module for an existing billing system that allows to update the billing system in real time on customers activities. Aradial allows reporting and easy export of usage to other systems.
Spotngo Payment module
Integrated solution designed for growth. The Hotspot/Wifi solution incorporates external, centralized Aradial Radius server (not embedded as other solutions) supporting a range of hotspot controllers allowing service providers to maintain as much control as desired over the usage of the hotspot while deploying a cost effective and scalable networks.
Spotngo main features are:
* External Access Point / Gateway bought from 3'rd party.
* Commercial Radius server software with time and traffic enforcement.
* Bandwidth Managment.
* Access restrictions based on time and day.
* Simple generation of users/cards accounts.
* Unlimited vouchers / prepaid cards.
* Configurable login page portal.
* UAM with: Mikrotik, Colubris, Nomadix, CheckPoint firewalls, Linksys, Chillispot, Monowall, PfSense, Proxim, Terabeam, ValuePoint, Planet, Zyxel, Ikarus, Buffalo Tech and more.
* Optional: Wifi Radius resells Mikrotik OS and WRAP Boxes.
* The Ability to brand and advertise your products.
* User Sign-up and Credit Card Payment using purchased prepaid cards.
* Present diffrent price list per Hotspot Location.
* Present diffrent captive portal pages per Hotspot Location.
* User self care module.
* Usage reports and statistics.
* Remote management of radius server and access point gateway.
* Extra users can be purchased as the hotspot grow.
* Additional Access Point / Gateway can be added at anytime.
* Users Management in a database.
* Optional: Credit Card payment, Pay Pal and pricing plans.
Aradial supports most Access Points and Access controllers on the market using its strong dictionaries capabilities and configurable Captive Portal (walled garden).
Some of the supported Access Points and Access controllers:
Colubris, Linksys with Chillispot, Nomadix, ValuePoint, Planet, Proxim, Cisco Aironet, Mikrotik, Bluesocket, ValuePoint, Planet, ZyXEL, Monowall, Handlink, Terabeam, Gemtek, Dlink and more.
Full integration with: NoCAT and Chillispot.
EAP based authentication
Aradial Radius is compliant with the following RADIUS RFCs that relate to WiFi:
* RFC 2284 - PPP Extensible Authentication Protocol (EAP)
* RFC 2548 - Microsoft Vendor-specific RADIUS Attributes
* RFC 2869 - RADIUS Extensions
Please check out our full Radius capabilities Aradial ISP and VOIP.
Advantages for hotspot providers
* Broad appeal to operators because of ease of use.
* Easy deployment and integration to network and billing systems.
* One-time setup with virtually no administration.
* Very secure solution.
* Reliability and high-performance.
* Configurable Portal and Self Care Module.
* Easy connection to Access servers such as D-link, Nomafix, Terabeam, Cisco and others.
* Easily handles both browser- and 802.1x-based access, ensuring compatibility with your environment today, and as you move to meet the security requirements of customers who prefer to connect via 802.1x.
* Complete time-based accounting of each customer's usage, ensuring that hotspots are fully compensated for the time each user spends on the network. Using RADIUS "Session Time-Out" attribute.
* Complete traffic accounting of each customer's usage, ensuring that hotspots are fully compensated for the traffic each user spends on the network. Using VSA RADIUS attributes per Access Point.
* Bandwidth management allowing to change/limit the bandwidth for users using VSA RADIUS attributes.
* The option for hotspot operators to establish and administer their own user database, or use an existing database in their infrastructure.
Features for Hotspots/WiMAX providers
* Customer Management system.
* Flexible RADIUS functionalities and extensions.
* Please review WiMAX page
Monday, March 2, 2009
Local Area Network Technologies Overview
Local Area Network (LAN) is a data communications network connecting terminals, computers and printers within a building or other geographically limited areas. These devices could be connected through wired cables or wireless links. Ethernet, Token Ring and Wireless LAN using IEEE 802.11 are examples of standard LAN technologies.
Ethernet is by far the most commonly used LAN technology. Token Ring technology is still used by some companies. FDDI is sometimes used as a backbone LAN interconnecting Ethernet or Token Ring LANs. WLAN using IEEE 802.11 technologies is rapidly becoming the new leading LAN technology for its mobility and easy to use features.
Local Area Network could be interconnected using Wide Area Network (WAN) or Metropolitan Area Network (MAN) technologies. The common WAN technologies include TCP/IP, ATM, Frame Relay etc. The common MAN technologies include SMDS and 10 Gigabit Ethernet.
LANs are traditionally used to connect a group of people who are in the same local area. However, the working group are becoming more geographically distributed in today's working environment. There, virtual LAN (VLAN) technologies are defined for people in different places to share the same networking resource.
Ethernet is by far the most commonly used LAN technology. Token Ring technology is still used by some companies. FDDI is sometimes used as a backbone LAN interconnecting Ethernet or Token Ring LANs. WLAN using IEEE 802.11 technologies is rapidly becoming the new leading LAN technology for its mobility and easy to use features.
Local Area Network could be interconnected using Wide Area Network (WAN) or Metropolitan Area Network (MAN) technologies. The common WAN technologies include TCP/IP, ATM, Frame Relay etc. The common MAN technologies include SMDS and 10 Gigabit Ethernet.
LANs are traditionally used to connect a group of people who are in the same local area. However, the working group are becoming more geographically distributed in today's working environment. There, virtual LAN (VLAN) technologies are defined for people in different places to share the same networking resource.
Local Area Network protocols are mostly at data link layer (layer 2). IEEE is the leading organization defining most of the LAN protocols.
Sample Wifi LAN Network:
Local Area Network Introduction
A network is a collection of computers and devices connected to each other. The network allows computers to communicate with each other and share resources and information. The Advance Research Projects Agency (ARPA) designed "Advanced Research Projects Agency Network" (ARPANET) for the United States Department of Defense. It was the first computer network in the world in late 1960's and early 1970
A wireless LAN (shortly WLAN) is a wireless local area network that links two or more computers or devices using spread-spectrum or OFDM modulation technology based to enable communication between devices in a limited area. This gives users the mobility to move around within a broad coverage area and still be connected to the network.
Let's began about type of LAN's Network.
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) network 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.
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
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.
There are 2 definitions for wireless LAN roaming:
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. A Mobile Station roaming from one access point to another often interrupts the flow of data between the Mobile Station and an application connected to the network. The Mobile Station, for instance, periodically monitors the presence of alternative access points (ones that will provide a better connection). At some point, based upon proprietary mechanisms, the Mobile Station decides to re-associate with an access point having a stronger wireless signal. The Mobile Station, however, may lose a connection with an access point before associating with another access point. In order to provide reliable connections with applications, the Mobile Station must generally include software that provides session persistence.[9]
External Roaming (2): The MS(client) moves into a WLAN of another Wireless Internet Service Provider (WISP) 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.
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