So most of the day today, I got to spin my wheels trying to figure out why we were getting intermittent network issues between a group of servers.

It was one of those days where you walk in the door and someone says, "Oh thank god you are here." before I even put down my laptop bag. So apparently this problem had been going on for about 1 1/2 weeks. And nobody could figure out why. So of course, I start checking the easy stuff right...

Frame size mismatch, IP address conflicts, checking even logs looking for errors, etc. Nothing. Everything looked ok. Start running ping tests all over the place. Server 1 can ping server 2, but server 2 gets 20% packet loss going to server 1. How the hell does that happen? Pings are 2 way communications, so if it works one way, it should work the other.

Then it dawns on me. So I start looking at the VMs involved. No, all of them have unique MACs. Hmmm.... Then I run a powershell script and look for duplicate MACs.... and my jaw drops...

5 different MACs have been duplicated.... on 10 different VMs. WTH?!?!

Who does that? why? do they not understand how networking works at all?

Jeez, and once I eliminate all the duplicate MACs, like magic all the dropped packets are gone.

OK, done ranting...

And now, of course, work thinks I'm again Scotty from Star Trek. I fixed in a few hours what they had been working on for 1 1/2 weeks...