Additional Wireless Terms; Wireless Security Overview - ZyXEL Communications P-660HN-51 User Manual

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

6.9.2 Additional Wireless Terms

The following table describes some wireless network terms and acronyms used in the Zyxel Device's Web
Configurator.
Table 21 Additional Wireless Terms
TERM
RTS/CTS Threshold
Preamble
Authentication
Fragmentation
Threshold

6.9.3 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.
Chapter 6 Wireless
DESCRIPTION
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.
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.
The process of verifying whether a wireless device is allowed to use the wireless
network.
A small fragmentation threshold is recommended for busy networks, while a
larger threshold provides faster performance if the network is not very busy.
P-660HN-51 User's Guide
79