ZyWALL Series Internet Security Gateway
Wireless LAN and IEEE 802.11
H-2
The IEEE 802.11 specifies three different transmission methods for the PHY, the layer responsible for
transferring data between nodes. Two of the methods use spread spectrum RF signals, Direct Sequence
Spread Spectrum (DSSS) and Frequency-Hopping Spread Spectrum (FHSS), in the 2.4 to 2.4825 GHz
unlicensed ISM (Industrial, Scientific and Medical) band. The third method is infrared technology, using
very high frequencies, just below visible light in the electromagnetic spectrum to carry data.
Ad-hoc Wireless LAN Configuration
The simplest WLAN configuration is an independent (Ad-hoc) WLAN that connects a set of computers with
wireless nodes or stations (STA), which is called a Basic Service Set (BSS). In the most basic form, a
wireless LAN connects a set of computers with wireless adapters. Any time two or more wireless adapters
are within range of each other, they can set up an independent network, which is commonly referred to as an
Ad-hoc network or Independent Basic Service Set (IBSS). The following diagram shows an example of
desktop and notebook computers using wireless adapters to form an Ad-hoc wireless LAN.
Diagram H-1 Peer-to-Peer Communication in an Ad-hoc Network
Infrastructure Wireless LAN Configuration
For Infrastructure WLANs, multiple Access Points (APs) link the WLAN to the wired network and allow
users to efficiently share network resources. The Access Points not only provide communication with the
wired network but also mediate wireless network traffic in the immediate neighborhood. Multiple Access
Summary of Contents for Internet Security Gateway ZyWALL 100
Page 1: ...ZyWALL 10W 30W 50 100 Internet Security Gateway User s Guide Version 3 62 February 2004 ...
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Page 124: ...ZyWALL Series Internet Security Gateway 8 16 WAN Screens Figure 8 10 Dial Backup Setup ...
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Page 235: ...ZyWALL Series Internet Security Gateway VPN Screens 15 11 Figure 15 5 VPN IKE ...
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Page 282: ...ZyWALL Series Internet Security Gateway 16 20 Certificates Figure 16 9 Trusted CA Details ...
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Page 351: ...Logs IX Part IX Logs This part provides information and instructions for the logs and reports ...
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Page 356: ...ZyWALL Series Internet Security Gateway 20 4 Log Screens Figure 20 2 Log Settings ...
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Page 365: ...Maintenance X Part X Maintenance This part covers the maintenance screens ...
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