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Wireless Networking Overview:
Dell™ TrueMobile™ 2300 Wireless Broadband Router User's Guide

Wireless Local Area Network (WLAN)

Identifying a WLAN

Encryption

Automatic Rate Selection and Rate Scaling

Wireless Local Area Network (WLAN)

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 standard and proposed 802.11g standard. All Dell 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.

A wireless client operates in either infrastructure mode or peer-to-peer mode.

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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 an access point or wireless adapter in a wireless client, the installation program asks you to enter the SSID. Dell cannot provide you with this information, as it is specific to your network; although, you may choose to use the default SSID, "wireless", for your Wireless Broadband Router. All wireless clients and access points in a WLAN must use the same network name.

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Encryption

In a WLAN, wireless clients and access points 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 access point encrypts or scrambles the information. The access point 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.

TrueMobile 2300 supports both WEP (Wired Equivalent Privacy) and WPA (Wi-Fi Protected Access).

WEP

WEP provides a way of creating an encrypted key that is shared between a wireless client (such as a notebook with a wireless PC card) and the router.  In Wireless Broadband Router, WEP is an optional feature that can be enabled or disabled.  When WEP encryption is enabled, you must set the WEP key in the client to match the WEP key used by the access point because you can ONLY connect to access points that have a matching WEP Key.

There are two WEP encryption methods:

• 40(64)-bit Encryption

• 104(128)-bit Encryption

40-bit and 64-bit encryption are 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, arrayed as follows:

Key #1: 1011121314

Key #2: 2021222324

Key #3: 3031323334

Key #4: 4041424344

A 104(128)-bit key has several trillion times as many possible combinations than a 40(64)-bit key. It consists of 26 hexadecimal numbers, arrayed as follows:

Key (#1): 101112131415161718191A1B1C

All wireless clients and access points 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 an access point is 40(64)-bit. The method for a wireless client is 104(128)-bit encryption. The client and access point cannot communicate with each other, even though the selected key is the same. To resolve this problem, set the access point to use 104(128)-bit encryption.

Example 2

The encryption method is the same for the access point and wireless client. You select key 1 for the access point 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.

The Wireless Broadband Router uses either hexadecimal digits or ASCII characters to create encryption keys. Hexadecimal digits include the numbers 0 to 9 and the letters A to F. For example, the decimal number 15 is represented as F in the hexadecimal numbering system.

ASCII is the acronym for the American Standard Code for Information Interchange. Pronounced ask-ee, ASCII is a code for representing English characters as numbers, with each letter assigned a number from 0 to 127. For example, the ASCII code for uppercase M is 77. Most computers use ASCII codes to represent text, which makes it possible to transfer data from one computer to another.

WPA

WPA is an upgrade to the WEP (Wired Equivalent Privacy) standard for securing your wireless network.  WPA is derived from and will be forward-compatible with the future IEEE 802.11i standard.  It provides improved data encryption and user authentication.

To enhance the level of security, WPA uses TKIP (Temporal Key Integrity Protocol) encryption to address the vulnerabilities of the static keys used in WEP (Wired Equivalent Privacy). TKIP includes four algorithms: MIC (message integrity check), to protect packets from tampering; PPK (Per-Packet Key) hashing, to prevent weak key attacks; extended IV (initialization vector), to reduce IV reuse and the possibility that a hacker will collect sufficient packets to crack the encryption; and a re-keying mechanism, to change the temporal key dynamically.  TKIP is the most commonly used encryption method; however, if your wireless clients do not support TKIP, TrueMobile 2300 also supports AES (Advanced Encryption Security) encryption.  AES will replace 802.11's RC4-based encryption under 802.11i specification.  AES, the gold-standard encryption algorithm, provides maximum security for wireless network.

For user authentication, WPA adopts an authentication scheme -- via 802.1x.  802.1x provides a framework for user authentication and a key distribution management method.  802.1x consists of three main elements: an Authentication Server (typically a RADIUS server), WPA-enabled router or AP (called "Authenticator"), and a WPA-enabled client (called "Supplicant").  802.1x ensures only authorized users can access the network.

In enterprises, WPA will be used in conjunction with both wireless router and authentication server.  In Small Office/ Home Office (SOHO) environment, where there are no authentication server, users can use pre-shared key (PSK) mode in place of the authentication server.  TrueMobile 2300 offers you WPA running in PSK mode.  The mutual authentication and improved encryption technology of WPA allows wireless communication to achieve greater security. 

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Automatic Rate Selection and Rate Scaling

In 802.11g, wireless network adapters and access points can transmit data at one of the following rates: 54, 48, 36, 24, 18, 12, 9, or 6 Mbps.  In 802.11b, the data can be transmitted at a rate of 11, 5.5, 2, or 1 Mbps.  As the distance between an adapter and access point increases or decreases, the data rate automatically changes. Other factors, like interference, also affect the data rate. The Wireless Broadband Router uses automatic rate selection and rate scaling to determine the most efficient rate of communication. Rate scaling maintains optimal communication between wireless clients and the WLAN.

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