[clue] Wireshark

[David L. Anselmi]

dennisjperkins at comcast.net wrote:
> I was told that one of our customers was having network issues with our analyzers, so he hooked
> up a laptop with Wireshark. Supposedly the problem went away when Wireshark was monitoring the
> network, which doesn't make sense to me. Has anyone seen anything like this?

So my thought when I saw this, and didn't have time to write, was that Wireshark didn't do anything. 
Instead the customer attained enlightenment.

If you want to describe how your analyzers use the network and what the issues were we might be able 
to guess the scenario more precisely. But here are the sorts of things I mean.

So the issue might be that a device can't communicate and the customer associates the beginning of 
that symptom with the installation (or activation) of the analyzer. By using Wireshark he sees that 
the cause is some other device using all the bandwidth, or the device is using the wrong IP address, 
or some other misconfiguration. He fixes it and the problem is gone but he doesn't want to admit it 
had nothing to do with you.

Or, as Charles suggested, adding Wireshark to the network caused the switch configuration to change, 
unscrewing whatever was screwed up in it.

It is possible that Wireshark has a more direct impact on the network that influences its behavior 
but I think it's unlikely that its impact, the issue, and your analyzer's behavior are closely 
enough related for that to happen.

If Wireshark is removed (meaning the steps taken to add it are reversed) does the problem come back? 
If not, it's not your analyzer. If so then I would look at what happens in each step and evaluate 
how that might affect the issue.

Also, if they're at all competent at troubleshooting they should be able to offer an explanation as 
to how the analyzer causes the problem. If not then probably all y'all need some help from someone 
who can troubleshoot. Otherwise "it's not magic but it works just like it". :-)

Good luck! Be interesting to hear what the resolution is.

Dave