21.3 WLAN Topologies WLANs can be built with either of the following topologies:
Peer-to-peer (ad hoc) topology
Access point-based topology
Point-to-multipoint bridge topology
In peer-to-peer topology, client devices within a cell communicate directly to
each other as shown in Figure 21.3.
AP-based technology uses access points to bridge traffi c onto a wired (Ethernet
or Token Ring) or a wireless backbone as shown in Figure 21.4. AP enables a
wireless client device to communicate with any other wired or wireless device on
the network. AP-based topology is more commonly used and demonstrates that
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21.3 WLAN Topologies 717 Ch21-P373580.indd 717
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718 21 Wireless Local Area Networks the WLAN does not replace the wired LAN, it extends connectivity to mobile
devices.
Another wireless network topology is the point-to-multipoint bridge. Wire-
less bridges connect LANs in one building to LANs in another building even if the
buildings are miles apart. These conditions receive a clear line-of-sight between
buildings. The line-of-sight range varies based on the type of wireless bridge and
antenna used as well as environmental conditions.
Distribution
System (DS)
Access Points (AP)
Infrastructure Network
BSS 2
Ad hoc Network
Figure 21.3 Peer-to-peer topology (Ad hoc Network). AP #1
AP #2
ST #1
ST #4
AP #4
Figure 21.4 Access point-based topology. Ch21-P373580.indd 718
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21.4 WLAN Technologies The technologies available for use in a WLAN include infrared, UHF (narrowband),
and spread spectrum implementation. Each implementation comes with its own set
of advantages and limitations.
