Netowork Issues for the new AC Unit

Every few weeks I switch sites with a colleague for cross-training.  This allows each of us to cover if someone calls sick, or leaves for a better opportunity.  The cross-training has worked out very well with positive feed back from the client at both sites.

This morning at 8:00 while looking over backup logs of laboratory PCs, I was asked by Brian (a contractor who is working on the some building automation) for some network assistance.  We have installed a new AC  unit which has ether-net connections for remote monitoring.  The unit was working about 2 weeks ago, but today it is not functional.  I tried to ping the unit from my desk but received “Host Unreachable”.  So I ran nslookup to see if the IP address I was trying to ping was assigned to this AC unit; confirmed that we have the right IP address.

I asked Brian if he knew what number was written on the data jack so I can see if it was disconnect in the network closet.  Brian said he was unable to read the writing on the data jack.  So I said I would check it out with him.  After getting on the roof we shut down the old AC unit to open the access panel.  Right in front of us was the data jacks with 2 connections – one for each AC unit with writing that was faded.  Maybe if the guys from CSI were with use  they could tell me what numbers were.  I swapped the ports to see if the connectivity lights activated on the new AC unit.  They did but I lost the lights for the old AC unit.  I reset the cables, closed the panel and power on the AC unit…looks like the problem is in the network closet.

At the network closet I check to see if any ports were labeled AC units – of course not.  So now I started up my PC and started one of my company provided network monitoring tools.  Brian supplied the IP address of the working AC unit and I began my search. I was able to find the exact data port connection on the switch and trace the wire back to the unlabeled patch panel.  So I took a guess the next unlabeled port would be the second connection on the roof.  And wouldn’t you know it, the cable was not connected to the switch.

After making the connection we tried to ping the new AC unit again – still host unreachable.  I had Brian go back to the roof and cycle the power for the new AC unit to see if that would resolve of connectivity issue.  We also verified the lights would come on and blink when we disconnected / connected the cable from the patch panel.  Still I could not ping the assigned IP address.  I contacted the network engineer and left him two voice messages with updates.  Brian gave me his business card and asked to be notified if there are any changes or new information.

Near the end of my work day, I decided to check the connection again for the new AC unit.  After receiving the same error messages from the ping command, I used the network monitoring tool to see if any information was available on the port I connect to.   Finally I had some information and called Brian.  It looks like the static IP address was reset to the factory standard IP of  I could also see MAC address and who the MAC Vendor was.

So now we wait for the vendor to come back and reprogram the ether-net card.  I sent an update by e-mail to my colleague to hopefully expect someone tomorrow or early next week.

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