User's Manual

Wireless Array
Configuring the Wireless Array 307
older, slower 802.11b stations. Protection avoids collisions by preventing
802.11b and 802.11g stations from transmitting simultaneously. When
Auto CTS or Auto RTS is enabled and any 802.11b station is associated to
the IAP, additional frames are sent to gain access to the wireless network.
• Auto CTS requires 802.11g stations to send a slow Clear To Send
frame that locks out other stations. Automatic protection reduces
802.11g throughput when 802.11b stations are present — Auto CTS
adds less overhead than Auto RTS. The default value is Auto CTS.
• With Auto RTS, 802.11g stations reserve the wireless media using a
Request To Send/Clear To Send cycle. This mode is useful when you
have dispersed nodes. It was originally used in 802.11b only
networks to avoid collisions from “hidden nodes” — nodes that are so
widely dispersed that they can hear the Array, but not each other.
When there are no 11b stations associated and an auto-protection mode is
enabled, the Array will not send the extra frames, thus avoiding
unnecessary overhead.
14. 802.11g Slot: Choose Auto to instruct the Array to manage the 802.11g
slot times automatically, or choose Short Only. Xirrus recommends using
Auto for this setting, especially if 802.11b devices are present.
15. 802.11b Preamble: The preamble contains information that the Array and
client devices need when sending and receiving packets. All compliant
802.11b systems have to support the long preamble. A short preamble
improves the efficiency of a network's throughput when transmitting
special data, such as voice, VoIP (Voice-over IP) and streaming video.
Select Auto to instruct the Array to manage the preamble (long and short)
automatically, or choose Long Only.
16. Fragmentation Threshold: This is the maximum size for directed data
packets transmitted over the 802.11b/g IAP. Larger frames fragment into
several packets, their maximum size defined by the value you enter here.
Enter the desired Fragmentation Threshold value, between 256 and 2346.