Avaya Wireless AP-3 User Manual

Avaya Wireless AP-3 User’s Guide                                                                                 4-25

DFS only applies to 802.11a APs used in Europe (i.e., units whose 
regulatory domain is set to ETSI). The European Telecommunications 
Standard Institute (ETSI) requires that 802.11a devices use DFS to 
prevent interference with radar systems and other devices that already 
occupy the 5 GHz band.

If you are using an 802.11a AP in Europe, keep in mind the following:

•  DFS is not a configurable parameter. It is always enabled and 

cannot be disabled.

•  You cannot manually select the device’s operating channel; you 

must let DFS select the channel.

•  You cannot configure the Auto Channel Select option. Within the 

HTTP interface, this option always appears enabled.

The 802.11 standard supports optional RTS/CTS communication based 
on packet size. Without RTS/CTS, a sending radio listens to see if 
another radio is already using the medium before transmitting a data 
packet. If the medium is free, the sending radio transmits its packet. 
However, there is no guarantee that another radio is not transmitting a 
packet at the same time, causing a collision. This typically occurs when 
there are hidden nodes (clients that can communicate with the 
Access Point but are out of range of each other) in very large cells.