Wireless Configuration for the SA 520W
Configuring the Radio
Cisco SA 500 Series Security Appliances Administration Guide
120
4
•
Fragmentation Threshold:
The fragmentation threshold is the frame length
that requires packets to be broken up (fragmented) into two or more frames.
Setting a lower value can reduce collisions because collisions occur more
often in the transmission of long frames, which occupy the channel for a
longer time. Use a low setting in areas where communication is poor or
where there is a great deal of radio interference. Set the threshold by
entering the frame length in bytes. The default value is 2346, which
effectively disables fragmentation.
•
Preamble mode:
802.11b requires that a preamble be appended to every
frame before it is transmitted through the air. The preamble can be either the
traditional long preamble, which requires 192
μ
s for transmission, or it can be
an optional short preamble that requires only 96
μ
s. The long preamble is
needed for compatibility with the legacy 802.11 systems operating at 1 and
2 Mbps. The default is Long.
•
Protection Mode:
Select
RTS/CTS protection
if you want the security
appliance to perform a RTS/CTS handshake before transmitting a packet.
This mode can minimize collisions among hidden stations.
•
U-APSD:
Check this box to conserve power by enabling the Unscheduled
Automatic Power Save Delivery (also referred to as WMM Power Save)
feature.
•
Short Retry Limit
,
Long Retry Limit:
Enter the number of times the security
appliance will retry a frame transmission that fails. Retries are used for both
long and short frames, of size less than or equal to the RTS threshold.
STEP 3
Click
Apply
to save your settings, or click
Reset
to revert to the saved settings.