Tsunami MP-8100 Installation and Management Guide 184
8.4.17 General Check
Two general checks are recommended before taking any action:
• Check whether the software version on all devices is the most current version.
• Check for any reported alarm messages in the Event Log.
8.4.18 Statistics Check
Interference and other negative environment factors always have an impact on the number of correctly received frames. The
Tsunami MP-8100 models give detailed information about transmission errors in the Web interface, under Monitor
(Section/Window etc.).
The windows that are important for validating the health of the link are:
• Monitor / Wireless Statistics: Check FCS errors: Rising FCS errors indicate interference or low fade margin. So does
Failed count. If only one of those is high, this indicates that a source of interference is significant near one end of the
link.
• Monitor / Ethernet Statistics: The information is given after the wireless Ethernet frame is converted into a normal
Ethernet frame. The parameters shown are part of the MIB-II.
– Both operational and admin status should be up. An admin status of down indicates that the interface is configured
to be down.
– In Discards and Out Discards indicate overload of the buffers, likely caused by network traffic, which is too heavy.
– In Errors and Out Errors should never happen; however, it might happen if a frame’s FCS was correct while the
content was still invalid.
• Monitor / Wireless / WORP (Statistics on WORP): WORP runs on top of normal Ethernet, which means that the WORP
frame is in fact the data field of the Ethernet frame. Send Failure or Send Retries must be low in comparison to Send
Success. Low is about 1%. The same applies for Receive Success versus Receive Retries and Receive Failures. Note that
the Receive Failures and Retries can be inaccurate. A frame from the remote site might have been transmitted without
even being received; therefore, the count of that frame might not have been added to the statistics and the receiver
simply could not know that there was a frame.
– Remote Partners indicates how many SU units are connected (in case of a BSU) or whether a BSU is connected (in
case of an SU).
8.4.19 Analyzing the Spectrum
The ultimate way to discover whether there is a source of interference is to use a spectrum analyzer. Usually, the antenna is
connected to the analyzer when measuring. By turning the antenna 360 degrees, one can check from which direction the
interference is coming. The analyzer will also display the frequencies and the level of signal is detected. Proxim recommends
performing the test at various locations to find the most ideal location for the equipment.
8.4.19.1 Avoiding Interference
When a source of interference is identified and when the level and frequencies are known, the next step is to avoid the
interference. Some of the following actions can be tried:
• Changing the channel to a frequency away from the interference is the first step in avoiding interference. The installer
can select a DFS Preferred Channel.
• Each antenna has a polarization; try to change to a polarization different from the interference.
• A small beam antenna looks only in one particular direction. Because of the higher gain of such an antenna, lowering
the output power or adding extra attenuation might be required to stay legal. This solution cannot help when the
source of interference is right behind the remote site.
• Lowering the antennas can help avoid seeing interference from far away.
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