Chapter 7 Wireless
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Figure 66
Basic Service Set
7.9.6 MBSSID
Traditionally, you need to use different APs to configure different Basic Service Sets (BSSs). As well as the
cost of buying extra APs, there is also the possibility of channel interference. The Zyxel Device’s MBSSID
(Multiple Basic Service Set IDentifier) function allows you to use one access point to provide several BSSs
simultaneously. You can then assign varying QoS priorities and/or security modes to different SSIDs.
Wireless devices can use different BSSIDs to associate with the same AP.
7.9.6.1 Notes on Multiple BSSs
• A maximum of eight BSSs are allowed on one AP simultaneously.
• You must use different keys for different BSSs. If two wireless devices have different BSSIDs (they are in
different BSSs), but have the same keys, they may hear each other’s communications (but not
communicate with each other).
• MBSSID should not replace but rather be used in conjunction with 802.1x security.
7.9.7 Preamble Type
Preamble is used to signal that data is coming to the receiver. Short and long refer to the length of the
synchronization field in a packet.
Short preamble increases performance as less time sending preamble means more time for sending
data. All IEEE 802.11 compliant wireless adapters support long preamble, but not all support short
preamble.
