Chapter 7 Wireless LAN

AMG1302/AMG1202-TSeries User’s Guide

106

7.9

The Advanced Screen

Use this screen to configure advanced wireless settings. Click

Network Setting

>

Wireless

>

Advanced

, the screen appears as shown.

See

Section 7.10.2 on page 109

for detailed definitions of the terms listed in this screen.

Figure 38

Network Setting > Wireless> Advanced

The following table describes the labels in this screen.

Time (24-Hour

Format)

Specify a time frame during which the schedule would apply.

For example, if you set the time range from 12:00 to 23:00, the wireless LAN will be

turned on only during this time period.

Apply

Click this to save your changes.

Cancel

Click this to restore your previously saved settings.

Table 26

Network Setting > Wireless > Scheduling

LABEL

DESCRIPTION

Table 27

Network Setting > Wireless> Advanced

LABEL

DESCRIPTION

Fragmentation

Threshold

This is the maximum data fragment size that can be sent. Enter a value between 256 and

2346.

Output Power

Set the output power of the AMG1302/AMG1202-TSeries. If there is a high density of APs

in an area, decrease the output power to reduce interference with other APs. Select one

of the following:

100%

,

75%, 50%

or

25%

.

Preamble

Select a preamble type from the drop-down list menu. Choices are

Long

or

Short

. See

the

Appendix D on page 285

for more information.

Chapter 7 Wireless LAN

AMG1302/AMG1202-TSeries User’s Guide

107

7.10

Wireless LAN Technical Reference

This section discusses wireless LANs in depth. For more information, see the appendix.

7.10.1

Wireless Network Overview

Wireless networks consist of wireless clients, access points and bridges.

•

A wireless client is a radio connected to a user’s computer.

•

An access point is a radio with a wired connection to a network, which can connect with

numerous wireless clients and let them access the network.

•

A bridge is a radio that relays communications between access points and wireless clients,

extending a network’s range.

Traditionally, a wireless network operates in one of two ways.

802.11 Mode

Select

802.11b Only

to allow only IEEE 802.11b compliant WLAN devices to associate

with the AMG1302/AMG1202-TSeries.

Select

802.11g Only

to allow only IEEE 802.11g compliant WLAN devices to associate

with the AMG1302/AMG1202-TSeries.

Select

802.11b+g

to allow either IEEE 802.11b or IEEE 802.11g compliant WLAN

devices to associate with the AMG1302/AMG1202-TSeries. The transmission rate of your

AMG1302/AMG1202-TSeries might be reduced.

Select

802.11n

to allow only IEEE 802.11n compliant WLAN devices to associate with the

AMG1302/AMG1202-TSeries.

Select

802.11g+n

to allow either IEEE 802.11g or IEEE 802.11n compliant WLAN

devices to associate with the AMG1302/AMG1202-TSeries. The transmission rate of your

AMG1302/AMG1202-TSeries might be reduced.

Select

802.11b+g+n

to allow IEEE 802.11b, IEEE 802.11g or IEEE802.11n compliant

WLAN devices to associate with the AMG1302/AMG1202-TSeries. The transmission rate of

your AMG1302/AMG1202-TSeries might be reduced.

Channel Width

Select whether the AMG1302/AMG1202-TSeries uses a wireless channel width of

20MHz

or

Auto

. If

Auto

is selected, the AMG1302/AMG1202-TSeries will use 40MHz if it is

supported.

A standard 20MHz channel offers transfer speeds of up to 150Mbps whereas a 40MHz

channel uses two standard channels and offers speeds of up to 300 Mbps.

40MHz (channel bonding or dual channel) bonds two adjacent radio channels to increase

throughput. The wireless clients must also support 40 MHz. It is often better to use the 20

MHz setting in a location where the environment hinders the wireless signal.

Select

20MHz

if you want to lessen radio interference with other wireless devices in your

neighborhood or the wireless clients do not support channel bonding.

This field is available only when you set the

802.11 Mode

to

802.11n

or

802.11b+g+n

in the

Advanced Setup

screen.

Apply

Click this to save your changes.

Cancel

Click this to restore your previously saved settings.

Table 27

Network Setting > Wireless> Advanced

LABEL

DESCRIPTION

Chapter 7 Wireless LAN

AMG1302/AMG1202-TSeries User’s Guide

108

•

An “infrastructure” type of network has one or more access points and one or more wireless

clients. The wireless clients connect to the access points.

•

An “ad-hoc” type of network is one in which there is no access point. Wireless clients connect to

one another in order to exchange information.

The following figure provides an example of a wireless network.

Figure 39

Example of a Wireless Network

The wireless network is the part in the blue circle. In this wireless network, devices

A

and

B

use the

access point (

AP

) to interact with the other devices (such as the printer) or with the Internet. Your

AMG1302/AMG1202-TSeries is the AP.

Every wireless network must follow these basic guidelines.

•

Every device in the same wireless network must use the same SSID.

The SSID is the name of the wireless network. It stands for Service Set IDentifier.

•

If two wireless networks overlap, they should use a different channel.

Like radio stations or television channels, each wireless network uses a specific channel, or

frequency, to send and receive information.

•

Every device in the same wireless network must use security compatible with the AP.

Security stops unauthorized devices from using the wireless network. It can also protect the

information that is sent in the wireless network.

Radio Channels

In the radio spectrum, there are certain frequency bands allocated for unlicensed, civilian use. For

the purposes of wireless networking, these bands are divided into numerous channels. This allows a

Chapter 7 Wireless LAN

AMG1302/AMG1202-TSeries User’s Guide

109

variety of networks to exist in the same place without interfering with one another. When you

create a network, you must select a channel to use.

Since the available unlicensed spectrum varies from one country to another, the number of

available channels also varies.

7.10.2

Additional Wireless Terms

The following table describes some wireless network terms and acronyms used in the AMG1302/

AMG1202-TSeries’s Web Configurator.

7.10.3

Wireless Security Overview

By their nature, radio communications are simple to intercept. For wireless data networks, this

means that anyone within range of a wireless network without security can not only read the data

passing over the airwaves, but also join the network. Once an unauthorized person has access to

the network, he or she can steal information or introduce malware (malicious software) intended to

compromise the network. For these reasons, a variety of security systems have been developed to

ensure that only authorized people can use a wireless data network, or understand the data carried

on it.

These security standards do two things. First, they authenticate. This means that only people

presenting the right credentials (often a username and password, or a “key” phrase) can access the

network. Second, they encrypt. This means that the information sent over the air is encoded. Only

people with the code key can understand the information, and only people who have been

authenticated are given the code key.

These security standards vary in effectiveness. Some can be broken, such as the old Wired

Equivalent Protocol (WEP). Using WEP is better than using no security at all, but it will not keep a

determined attacker out. Other security standards are secure in themselves but can be broken if a

user does not use them properly. For example, the WPA-PSK security standard is very secure if you

use a long key which is difficult for an attacker’s software to guess - for example, a twenty-letter

long string of apparently random numbers and letters - but it is not very secure if you use a short

key which is very easy to guess - for example, a three-letter word from the dictionary.

Because of the damage that can be done by a malicious attacker, it’s not just people who have

sensitive information on their network who should use security. Everybody who uses any wireless

network should ensure that effective security is in place.

A good way to come up with effective security keys, passwords and so on is to use obscure

information that you personally will easily remember, and to enter it in a way that appears random

and does not include real words. For example, if your mother owns a 1970 Dodge Challenger and

Table 28

Additional Wireless Terms

TERM

DESCRIPTION

Preamble

A preamble affects the timing in your wireless network. There are two preamble

modes: long and short. If a device uses a different preamble mode than the

AMG1302/AMG1202-TSeries does, it cannot communicate with the AMG1302/

AMG1202-TSeries.

Authentication

The process of verifying whether a wireless device is allowed to use the wireless

network.

Fragmentation

Threshold

A small fragmentation threshold is recommended for busy networks, while a larger

threshold provides faster performance if the network is not very busy.

Chapter 7 Wireless LAN

AMG1302/AMG1202-TSeries User’s Guide

110

her favorite movie is Vanishing Point (which you know was made in 1971) you could use

“70dodchal71vanpoi” as your security key.

The following sections introduce different types of wireless security you can set up in the wireless

network.

7.10.3.1

SSID

Normally, the AMG1302/AMG1202-TSeries acts like a beacon and regularly broadcasts the SSID in

the area. You can hide the SSID instead, in which case the AMG1302/AMG1202-TSeries does not

broadcast the SSID. In addition, you should change the default SSID to something that is difficult

to guess.

This type of security is fairly weak, however, because there are ways for unauthorized wireless

devices to get the SSID. In addition, unauthorized wireless devices can still see the information that

is sent in the wireless network.

7.10.3.2

MAC Address Filter

Every device that can use a wireless network has a unique identification number, called a MAC

address.

1

A MAC address is usually written using twelve hexadecimal characters

2

; for example,

00A0C5000002 or 00:A0:C5:00:00:02. To get the MAC address for each device in the wireless

network, see the device’s User’s Guide or other documentation.

You can use the MAC address filter to tell the AMG1302/AMG1202-TSeries which devices are

allowed or not allowed to use the wireless network. If a device is allowed to use the wireless

network, it still has to have the correct information (SSID, channel, and security). If a device is not

allowed to use the wireless network, it does not matter if it has the correct information.

This type of security does not protect the information that is sent in the wireless network.

Furthermore, there are ways for unauthorized wireless devices to get the MAC address of an

authorized device. Then, they can use that MAC address to use the wireless network.

7.10.3.3

User Authentication

Authentication is the process of verifying whether a wireless device is allowed to use the wireless

network. You can make every user log in to the wireless network before using it. However, every

device in the wireless network has to support IEEE 802.1x to do this.

For wireless networks, you can store the user names and passwords for each user in a RADIUS

server. This is a server used in businesses more than in homes. If you do not have a RADIUS server,

you cannot set up user names and passwords for your users.

Unauthorized wireless devices can still see the information that is sent in the wireless network,

even if they cannot use the wireless network. Furthermore, there are ways for unauthorized

wireless users to get a valid user name and password. Then, they can use that user name and

password to use the wireless network.

1.

Some wireless devices, such as scanners, can detect wireless networks but cannot use wireless networks. These kinds

of wireless devices might not have MAC addresses.

2.

Hexadecimal characters are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F.