Chapter 7 Wireless
VMG/XMG Series User’s Guide
172
• 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.
7.11.2 Additional Wireless Terms
The following table describes some wireless network terms and acronyms used in the Zyxel Device’s Web
Configurator.
7.11.3 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.
Table 50 Additional Wireless Terms
TERM DESCRIPTION
RTS/CTS Threshold In a wireless network which covers a large area, wireless devices are sometimes not
aware of each other’s presence. This may cause them to send information to the AP at
the same time and result in information colliding and not getting through.
By setting this value lower than the default value, the wireless devices must sometimes get
permission to send information to the Zyxel Device. The lower the value, the more often
the devices must get permission.
If this value is greater than the fragmentation threshold value (see below), then wireless
devices never have to get permission to send information to the Zyxel Device.
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 Zyxel Device does, it
cannot communicate with the Zyxel 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.
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