Chapter 7 Wireless LAN
P-660HN-FxZ Series User’s Guide
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7.9.2
Additional Wireless Terms
The following table describes some wireless network terms and acronyms used in the ZyXEL
Device’s Web Configurator.
7.9.3
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.
Table 42
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.
IGMP
Traditionally, IP packets are transmitted in one of either two ways - Unicast (1
sender to 1 recipient) or Broadcast (1 sender to everybody on the network).
Multicast delivers IP packets to just a group of hosts on the network.
IGMP (Internet Group Management Protocol) is a network-layer protocol used
to establish membership in a multicast group - it is not used to carry user data.
IGMP Snooping
The ZyXEL Device can passively snoop on IGMP packets transferred
between IP multicast routers/switches and IP multicast hosts to learn the IP
multicast group membership. It checks IGMP packets passing through it, picks
out the group registration information, and configures multicasting
accordingly. IGMP snooping allows the ZyXEL Device to learn multicast
groups without you having to manually configure them.
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