3Com 3CRGPC10075, User Manual

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122 A
PPENDIX
C: W
IRELESS
LAN B
ASICS
ESS/ESSID A group of wireless stations and multiple Access Points, all using the
same ID (ESSID), form an Extended Service Set (ESS).
Different Access Points within an ESS can use different channels. To
reduce interference, it is recommended that adjacent Access Points
should use different channels.
As wireless stations are physically moved through the area covered by an
ESS, they will automatically change to the Access Point which has the
least interference or best performance. This capability is called roaming.
Access Points do not have or require roaming capabilities.
Wireless Channels
The wireless channel sets the radio frequency used for communication.
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Access Points use a fixed channel, which is user-configurable. This
allows you to choose a channel that provides the least interference
and best performance. For 802.11g, 13 channels are available in the
USA and Canada, but 11 channels are available in North America if
using 802.11b.
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If using multiple Access Points, it is better if adjacent Access Points use
different channels to reduce interference. The recommended channel
spacing between adjacent Access Points is 5 channels (for example,
use Channels 1 and 6, or 6 and 11).
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In infrastructure mode, wireless stations normally scan all channels to
search for an active Access Point. If more than one Access Point can
be used, the one with the strongest signal is used. (This can only
happen within an ESS.)
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In ad hoc mode, all wireless stations should be set to use the same
channel. However, most wireless stations will still scan all channels to
see if there is an existing ad hoc group they can join.
Security Settings
WEP Wired Equivalent Privacy (WEP) is a standard for encrypting data before it
is transmitted. This is desirable because it is impossible to prevent
snoopers from receiving any data which is transmitted by your wireless
stations. But if the data is encrypted, then it is meaningless unless the
receiver can decrypt it.
If WEP is used, the wireless stations and the Access Point must have the
same settings.