ZyXEL Communications eircom D1000, Руководство пользователя

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eircom D1000 modem U
ser’s Guide
Chapter 5 Wireless LAN
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
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.
5.10.2 Additional Wireless Terms
The following table describes some wireless network terms and acronyms used in the Device’s Web
Configurator.
Table 19
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 Device
does, it cannot communicate with the Device.
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.
5.10.3 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