ZyXEL Communications VSG1435-B101 - V1.10, Manual

Page: 117 / 412

Chapter 7 Wireless
VSG1435-B101 Series User’s Guide
117
• 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.
7.9.2 Additional Wireless Terms
The following table describes some wireless network terms and acronyms used in
the ZyXEL Device’s Web Configurator.
Table 22 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.