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When running cable diagnostics from a WS-12-DC how is cable length being determined? I am trying to determine why one cable to an ePMP AP shows a length of 531ft and another shows 236ft . Same tower, same run path, and only 50ft apart on tower. If it is an impedance test then I have a cabling issue.

lligetfa wrote:The way cable length is measured is with TDR (Time Domain Reflectometry) Where is measures how long it takes for the pulse to reflect back.

But yes your cable was either stretch, kinked, or damaged in some way during installation.

That was what I was thinking, thanks for the quick reply

Currently we are using GigE-APC surge suppressor cards. Is it possible that these are affecting the measurement.

md1man42 wrote:Currently we are using GigE-APC surge suppressor cards. Is it possible that these are affecting the measurement.

ABSOLUTELY

I hate Ethernet surge protectors.

In reality most damage to Ethernet equipment does not come from surges but rather from ground potential shifts because most WISPs do not invest properly in a good grounding system replying on the steel tower as the path to Earth Ground and do not bond the tower grounds to the service grounds.

Ethernet Surge Protectors provide ZERO protection against this damage, but they can cause packet errors.

Here are some good posts on grounding:
viewtopic.php?f=30&t=1816
viewtopic.php?f=30&t=188
viewtopic.php?f=30&t=1429
viewtopic.php?f=17&t=1786&start=30#p13447
https://community.ubnt.com/t5/airFiber/ ... rue#M31070
Ethernet Surge Protectors will help with Static and ESD discharges but ESD is more rare than people realize and Static is discharge is more common than ESD.