Chapter 7 Wireless
VMG4927-B50A / VMG9827-B50A / VMG3927-B50B User’s Guide
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7.8.2 Additional Wireless Terms
The following table describes some wireless network terms and acronyms used in the VMG’s Web
Configurator.
7.8.3 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.
Security standards vary in effectiveness. The WPA2-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 her favorite movie is
Vanishing Point (which you know was made in 1971) you could use “70dodchal71vanpoi” as your
security key.
Table 26 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 VMG. 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 VMG.
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 VMG does, it cannot
communicate with the VMG.
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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