What Is 802.11 Wireless?
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
What Is 802.11 Wireless?
The wireless local area network (WLAN) protocol, IEEE 802.11, and associated technologies, such as the 802.1X protocol and Wi-Fi Protected Access (WPA), allow secure high-speed wireless network access and mobile access to a network infrastructure. Until the recent development and wide adoption of IEEE 802.11b, also known as Wi-Fi, in order to obtain high-speed network access to your local area network (LAN) your network client needed to be physically connected to the LAN with some type of wiring.
Some of the specific benefits of implementing a WLAN are included in the following:
Wireless connections can extend or replace a wired infrastructure
In situations where it is costly, inconvenient, or impossible to lay cables, wireless connections can extend or replace a wired infrastructure. This benefit includes the following:
To connect the networks in two buildings separated by a physical, legal, or financial obstacle, you can either use a link provided by a telecommunications vendor (for a fixed installation cost and ongoing recurring costs) or you can create a point-to-point wireless link using wireless LAN technology (for a fixed installation cost, but no recurring costs). Eliminating recurring telecommunications charges can provide significant cost savings.
Wireless LAN technologies can be used to create a temporary network, which is in place for only a specific amount of time. For example, the network needed at a convention or trade show can be a wireless network, rather than deploying the physical cabling required for a traditional Ethernet network.
Some types of buildings, such as historical buildings, might be governed by building codes that prohibit the use of wiring, making wireless networking an important alternative.
The wiring-free aspect of wireless LAN networking is also very attractive to homeowners who want to connect the various computers in their home together without having to drill holes and pull network cables through walls and ceilings.
Increased productivity for the mobile employee
This benefit includes the following:
The mobile user whose primary computer is a portable computer can change location and always remain connected to the network. This enables the mobile user to travel to various places — meeting rooms, hallways, lobbies, cafeterias, classrooms, and so forth — yet retain access to networked data. Without wireless access, the user has to carry cabling and is restricted to working near a network jack.
Wireless LAN networking is a perfect technology for environments where movement is required. For example, retail environments can benefit when employees use a wireless portable computer or handheld device to enter inventory information directly into the store database from the sales floor.
Even if no wireless infrastructure is present, wireless portable computers can still form their own ad hoc networks to communicate and share data with each other.
Easy access to the Internet in public places
Beyond the corporate workplace, access to the Internet and even corporate sites can be made available through public wireless “hot spot” networks. For example, many airports, conference centers, and hotels provide wireless access to the Internet for their visitors. When a traveling worker reaches his or her destination, perhaps meeting a client at a corporate office, limited access can be provided to the traveling worker through the local wireless network. The network can recognize the traveling worker from another corporation and create a connection that provides Internet access to the visiting user, but is isolated from the local corporate network.
- In all these wireless LAN scenarios, it is worth noting that today’s standards-based wireless LANs operate at the same speeds that were considered state of the art for wired networks just a few years ago. For example, IEEE 802.11b, a prevalent wireless LAN technology, operates at a maximum of 11 megabits per second (Mbps), or about 30 to 100 times faster than standard dial-up technologies. This data transfer rate is adequate for running a number of applications or services. In addition, ongoing advancements of wireless standards continue to increase the data transfer rate, with speeds of up to 54 Mbps for IEEE 802.11g.
Dependencies and Associated Technologies
In a enterprise environment, secure 802.11 wireless technology has specific dependencies and other technologies with which it is typically associated.
Dependencies for a secure WLAN
The dependencies of a secure WLAN include the following:
A standard TCP/IP network environment.
Active Directory, to store account properties and validate password-based credentials.
Remote Authentication Dial-In User Service (RADIUS) support, to provide centralized connection authentication, authorization, and accounting.
A certificate infrastructure, also known as a public key infrastructure (PKI), to issue and validate the certificates required for Extensible Authentication Protocol–Transport Layer Security (EAP-TLS) and Protected EAP (PEAP)–TLS authentication. TLS can use either computer certificates for authenticating the wireless client computer or smart cards or registry-based user certificates for authenticating the user of a wireless client computer.
For PEAP-Microsoft Challenge Handshake Authentication Protocol version 2 (MS-CHAP v2) authentication, computer certificates for the RADIUS servers and root CA certificates of the issuing CAs on the wireless clients (if needed).
The associated technologies of a secure WLAN include the following:
WPA, as agreed upon by wireless vendors, is an interoperable interim standard until the IEEE 802.11i standard is being ratified. WPA requires secure wireless networking, addresses the issues with WEP through a software upgrade, provides a secure wireless networking solution for small office/home office (SOHO) wireless users, and provides compatibility with the upcoming IEEE 802.11i standard.
Dynamic Host Configuration Protocol (DHCP) services, to provide automatic Internet Protocol (IP) configuration to wireless clients.
Domain Name System (DNS) and Windows Internet Name Service (WINS) services, to provide name resolution.
- For information about IEEE 802.11b wireless networks for the home and small business, see the Microsoft Wi-Fi Web page.
802.11 Wireless Network Infrastructure
The following figure shows a simple example of a WLAN using a wireless access point and some of the Windows Server 2003 technologies on which a secure WLAN is dependent.
Example Wireless Network Infrastructure