A Local Area Network (LAN) is a network in one location. Users at that
location can share files, printers, and other services. In a LAN, a networked computer that requests services is called a client. A Wireless Local Area
Network (WLAN) is a type of LAN that uses high frequency radio waves rather than
wires to communicate and transmit data among the network clients and devices. It
is a flexible data communication system implemented as an extension to, or as an
alternative for, a wired LAN.
In a WLAN, wireless adapters are installed in clients, also called wireless
clients. The adapter allows the wireless client to communicate with the WLAN
without cables. Instead, wireless clients send and receive information through a
path in the air called a channel.
The standards for a WLAN are based on the IEEE 802.11b/g standard. All Dell
TrueMobile 802.11b/g-compliant devices interoperate with other
802.11b/g-compliant
wireless devices from other vendors. The WiFi certification logo indicates that
the wireless device has been tested by an independent organization and is
802.11b/g-compliant.
A wireless client operates in either infrastructure mode or peer-to-peer mode.
Infrastructure Mode: A WLAN with Wireless Broadband Routers
In infrastructure mode, wireless clients send and receive information through
one or more Wireless Broadband Routers. Wireless Broadband Routers are
strategically located within an area to provide optimal coverage for wireless
clients. Wireless Broadband Routers and wireless clients constitute a WLAN.
Wireless Broadband Routers can be connected to a LAN of wired or wireless
clients. The Wireless Broadband Routers send and receive information from the
LAN through this connection.
An Extended Service Set Identifier (ESSID) is used to identify the wireless
clients and Wireless Broadband Routers in a WLAN. All wireless clients and
Wireless Broadband Routers in the WLAN must use the same ESSID. A Basic Service
Set Identifier (BSSID) uniquely defines each wireless client and
Wireless Broadband Router.
Peer-to-Peer Mode (Ad Hoc): A WLAN without Wireless Broadband Routers
In peer-to-peer mode, wireless clients directly send and receive information
to other wireless clients without using a Wireless Broadband Router.
Identifying a WLAN
An ESSID and BSSID are both Service Set Identifiers (SSID) that identify and
control the wireless client�s access to a given WLAN. The SSID is sometimes
referred to as the network name. The SSID indicates what WLAN you are referring
to. In most cases, the user interface displays the SSID.
When installing a Wireless Broadband Router or wireless adapter in a wireless
client, the installation program asks you to enter the SSID.
All wireless clients and Wireless Broadband Routers in a WLAN must use the same
network name.
Encryption
In a WLAN, wireless clients and Wireless Broadband Routers send and receive
information through the air. Without implementing security, it is possible for
an unauthorized person to intercept the information.
A common way of implementing security and protecting information is encryption.
Encryption applies a set of instructions, called an algorithm, to information.
The instructions combine the plain or clear text of information with a sequence
of hexadecimal numbers, called an encryption key.
Before transmitting information over the airwaves, the wireless client or
Wireless Broadband Router encrypts or scrambles the information. The Wireless
Broadband Router or wireless client receiving the information uses the same key
to decrypt or unscramble the information. The information is only readable to WLAN devices that have the correct encryption key. The longer the key is, the
stronger the encryption.
The form of data encryption used by the Wireless Broadband Router is called
Wired Equivalent Privacy (WEP). When encryption is enabled, you must set the WEP
key in the client to match the WEP key used by the Wireless Broadband Router
because you will ONLY associate to Wireless Broadband Routers that have a
matching WEP Key. For added security, change the encryption key often. WEP, or
encryption, is an optional feature that can be enabled or disabled.
There are two WEP encryption methods: 40(64)-bit and 104(128)-bit. 40-bit and 64-bit
encryption is identical similarly 104-bit and 128-bit encryption is identical. Some vendors use the term 40-bit; others use 64-bit.
A wireless device that claims to have 40-bit encryption interoperates with a
device that claims to have 64-bit encryption, and vice versa. A 40(64)-bit key
consists of 10 hexadecimal numbers in five two-digit groups, arrayed as
follows:
Example Key #1: 1A:2E:3F:11:18
A 128-bit hexadecimal key has several trillion times as many possible
combinations than a 40(64)-bit key. It consists of 26 hexadecimal numbers
arranged in thirteen two-digit groups, arrayed as follows:
Example Key #1: 1A:2D:3E:5F:4A:22:19:77:91:A1:B2:C3:D8
The
examples above are for hexadecimal key format.Keys may also be in ASCII format.ASCII
characters consist of any numbers or letters in upper or lower case.The key may be 40(64)-bit ASCII, which consists of five characters (for
example: 12Abc).The key may also be 104(128)-bit ASCII, which consists of
thirteen characters (for example: AbCdEf1234567).Note the case of the
letters is important and �abcde� is not the same as �ABCDE�.
All wireless clients and Wireless Broadband Routers in a WLAN must use the same
encryption method and key. The following two examples stress how
important this point is.
Example 1
The encryption method for a Wireless Broadband Router is 40(64)-bit. The method
for a wireless client is 128-bit encryption. The client and Wireless Broadband
Router cannot communicate with each other, even though the selected key is the
same. To resolve this problem, set the Wireless Broadband Router to use 128-bit
encryption.
Example 2
The encryption method is the same for the Wireless Broadband Router and wireless
client. You select key 1 for the Wireless Broadband Router and key 2 for the
wireless client. The wireless client cannot communicate with the WLAN. To
resolve this problem, select key 1 for the wireless client.
