ZyXEL GS-105I User Guide - Page 106

Chapter 7 Wireless • 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 29 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. Preamble Authentication Fragmentation Threshold 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. 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. PX7511-B0 User's Guide 106