D-Link NetDefend DFL-CP310 User Manual page 200

Troubleshooting Wireless Connectivity
• Check the Transmission Power parameter in the WLAN's advanced settings
(see Manually Configuring a WLAN on page 165).
•
Make sure that you are not u
on the same frequency. For minimum interference, channel separation
between nearby access points must be at least 25 MHz (5 channels).
• The NetDefend firewall supports XR (Extend
best range, enable XR mode in the WLAN's advanced setting
Manually Configuring a WLAN on page 165), and use XR-enabled
stations.
• Range outdoors is normally much higher than indoors, depending on
environmental conditions.
Note: You can observe any changes in the wireless reception in the Active Computers
page. Make sure to refresh the page after making a change.
Note: Professional companies are available for help in setting up reliable wireless
networks, with access to specialized testing equipment and procedures.
There are excessive collisions between wireless stations. What should I do?
If you have many concurrently active wireless stations, there may be collisions
between them. Such collisions may be the result of a "hidden node" problem: not
all of the stations are within range of each other, and therefore are "hidden" from
one another. For example, if station A and station C do not detect each other, but
both stations detect and are detected by station B, then both station A and C may
attempt to send packets to station B simultaneously. In this case, the packets will
collide, and Station B will receive corrupted data.
The solution to this problem lies in the use of the RTS protocol. Before sending a
certain size IP packet, a station sends an RTS (Request To Send) packet. If the
recipient is not currently receiving packets from another source, it sends back a
CTS (Clear To Send) packet, indicating that the station can send the IP packet. Try
setting the RTS Threshold parameter in the WLAN's advanced settings (see
Manually Configuring a WLAN on page 165) to a lower value. This will cause
stations to use RTS for smaller IP packets, thus decreasing the likeliness of
collisions.
184
sing two access points in close proximity and
ed Range) technology. For
s (see
D-Link NetDefend firewall User Guide