Appendix D Wireless LANs
VMG1312-B Series User’s Guide
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An ESSI D (ESS I Dent ificat ion) uniquely ident ifies each ESS. All access point s and their associat ed
wireless client s wit hin t he sam e ESS m ust have t he sam e ESSI D in order to com m unicate.
Figure 196 I nfrast r ucture WLAN
Channel
A channel is t he radio frequency( ies) used by wireless devices t o t ransm it and r eceive dat a.
Channels available depend on your geographical area. You m ay have a choice of channels ( for your
region) so you should use a channel different from an adjacent AP (access point ) t o reduce
interference. I nt erference occurs when radio signals from differ ent access points overlap causing
interference and degrading perform ance.
Adjacent channels partially overlap however. To avoid interference due t o overlap, your AP should
be on a channel at least five channels away from a channel that an adj acent AP is using. For
exam ple, if your region has 11 channels and an adj acent AP is using channel 1, t hen you need t o
select a channel between 6 or 11.
RTS/CTS
A hidden node occurs when t wo st at ions are within range of the sam e access point , but are not
wit hin range of each other. The following figure illust rat es a hidden node. Both stations ( STA) are
wit hin range of t he access point ( AP) or wireless gateway, but out-of- range of each other, so they
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