WLAN Topologies
Use of the Cisco Aironet line of wireless products falls into three categories:
■ Client access, which allows mobile users to access the wired LAN
resources
■ Wireless connections between buildings
■ Wireless mesh
Wireless connections can be made in ad-hoc mode or infrastructure mode.
Ad-hoc mode (or Independent Basic Service Set [IBSS]) is simply a group of
computers talking wirelessly to each other with no access point (AP). It is
limited in range and functionality. Infrastructure mode’s BSS uses one AP to
connect clients. The range of the AP’s signal, called its microcell, must
encompass all clients. The Extended Service Set (ESS) uses multiple APs
with overlapping microcells to cover all clients. Microcells should overlap by
10–15 percent for data, and 15–20 percent for voice traffic. Each AP should
use a different channel.
Wireless repeaters extend an AP’s range. They use the same channel as their
AP, they must be configured with the AP’s SSID, and they should have 50
percent signal overlap.
Workgroup bridges connect to devices without a wireless network interface
card (NIC) to allow them access to the wireless network.
Wireless mesh networks can span large distances because only the edge APs
connect to the wired network. The intermediate APs connect wirelessly to
multiple other APs and act as repeaters for them. Each AP has multiple paths
through the wireless network. The Adaptive Wireless Path (AWP) protocol
runs between APs to determine the best path to the wired network. APs
choose backup paths if the best path fails.