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I have an issue where an app that is dependent on file locks crashes on Windows 10. The programmers tell me that app is extremely sensitive to packet loss, so I would like to detect what is happening in LAN communication to actually see if and when the packet is lost.

What tools can I use to do this?

Thansk

mrmut
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  • Just on an off the wall chance. Are these files stored on a mapped network drive that is mapped on the machine by group policy? And is that group policy set to “replace” mode rather than “update?” Many users are not aware that the “replace” mode behaves different on Win 8 and Win 10 than on Windows 7 and older. Replace mode will cause the drive map to disconnect and reconnect at every GPO refresh without further policy tweaks. – Appleoddity Aug 09 '18 at 04:07
  • Btw, the tool for load testing and monitoring packet loss on a network is ‘iperf’. – Appleoddity Aug 09 '18 at 04:08
  • @Appleoddity it is set to replace. I was not aware of this issue, but did notice that drive maps get mounted live. What is the timeout? Will try iperf. Thanks. – mrmut Aug 10 '18 at 06:31
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    The drives reconnect and will crash any database type system that requires a constant connection every time group policy updates. That is about every 60 to 90 minutes. You can test this theory by running `gpupdate` at the command prompt and see if the software crashes. – Appleoddity Aug 10 '18 at 06:34
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    @Appleoddity Your suggestion fixed the underlying problem! TBH I don't know what MS was thinking regarding replace policy. I put all of the policies to update, and voila - everything works perfectly. Thank you very much, you saved my butt! - Will you reply below, so I can select your answer as correct? - I dont have enough points to upvote comments yet (I have on other accounts, but not here). – mrmut Aug 10 '18 at 15:10

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Wireshark is a popular protocol analyzer / packet sniffer. It's free, and a lot of documentation is available to help you use it.

Here are some Wireshark Q&A pages that might be helpful for detecting packet loss:

A thread from ResearchGate:

And one Network Engineering Stack Overflow page:

freginold
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  • I agree wireshark is good for seeing what is happening on the wire, but it’s the wrong tool for determining “packet loss.” – Appleoddity Aug 09 '18 at 04:04
  • @Appleoddity Curious... why do you say it's the wrong tool? Many people use it for that purpose. – freginold Aug 09 '18 at 13:01
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    Wireshark is a packet analyzer. It can’t analyze what doesn’t exist. A dropped packet does not show up in a packet analyzer. You can only guess as to why the expected packets didn’t show up in Wireshark. Could be firewall, could be a bug in the software, etc. it’s also very complicated for an untrained eye to follow the series of packets in wireshark. I would never suggest or teach to someone to use wireshark for line quality testing. That’s not what it does. One good tool to test line quality is iperf. Just like we don’t use a packet analyzer for WiFi signal issues. We use a spectrum analyzer – Appleoddity Aug 09 '18 at 13:24