ZyXEL Communications ZYWALL USG 20 Manual page 804

Appendix C Wireless LANs
with each other. When Intra-BSS is disabled, wireless client A and B can still
access the wired network but cannot communicate with each other.
Figure 450 Basic Service Set
ESS
An Extended Service Set (ESS) consists of a series of overlapping BSSs, each
containing an access point, with each access point connected together by a wired
network. This wired connection between APs is called a Distribution System (DS).
This type of wireless LAN topology is called an Infrastructure WLAN. The Access
Points not only provide communication with the wired network but also mediate
wireless network traffic in the immediate neighborhood.
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ZyWALL USG 20/20W User's Guide