802.11g
Figure 6-1 802.11g Cell with No 802.11b Clients
Assume that initially 802.11b clients do not exist. The default behavior of an AP is to send
beacons that include information about the AP and the wireless cell. Without 802.11b
clients, the AP sends the following information in a beacon:
NON_ERP present: no
Use Protection: no
ERP is Extended Rate Physical. These are devices that have extended data rates. In other
words, NON_ERP is talking about 802.11b clients. If they were ERP, that would support
the higher data rates, making them 802.11g clients.
Now, going back to Figure 6-1 with no 802.11b clients, the AP tells everyone that 802.11b
clients are unavailable and that they do not need to use protection mechanisms.
After an 802.11b client associates with the AP, things change. In Figure 6-2, the AP alerts
the rest of the network about the NON_ERP client. This is done in the beacon that the
AP sends.
Beacon:
Non-ERP Present: Yes
Use Protection: Yes
Client A
Client B
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