Proxmox - Windows Server 2008 VM's cannot ping each other

Posted on 2012-09-11
Last Modified: 2012-09-11
I have a Proxmox 1.9 server that we are going to be using to host 2 Windows Server 2008 VM's (one DC, one Exchange server).  The server is a Dell PowerEdge R710 and everything seems to be fine.  We did an initial install of a 'blank' Windows Server 2008 VM, backed it up with vzdump and then used qmrestore to clone that blank into each of our Windows Server 2008 VM's.  We setup AD on the DC, joined the second VM to it and installed Exchange.  All was well until we noticed that we had a typo in the domain name.  No biggie.  We shut down the two VM's, restored two more and started over.  On the two newly created VM's though, they aren't talking.  I can ping anything on the planet (including the IP assigned to vmbr0) and I can ping both of the VM's from the Proxmox console.  I cannot ping between the two servers.  If I do an arp -a, I do not see the 'other' server from either server.  If I ping (the broadcast), I do not see the 'other' server from either server.  Each time, I just get destination host unreachable.  If I add a static arp entry (arp -s <ip address> <mac address>), I get a request timed out.  What am I missing?
Question by:cybertechcafe

    Author Comment

    Ok, just powered on the old machines (same names, same IP's) and am able to ping between them.  I did an arp -d * on each and confirmed MAC's were different (I had removed the ethernet interface on each and re-added with a different vendor type, just to make sure).

    Accepted Solution

    Ok, I've been banging my head against this with all manner of tools and trinkets trying to engineer a solution based on data and solid intel.  Ultimately, and out of desperation more than anything else, I deleted the (Realtek) virtual adapters from both servers and then added new (Intel e1000) virtual adapters from both machines.  I gave them the same IP addresses and fired up a console window and ping....   worked.  Joined the Exchange server to the domain, no problem at all.

    Author Closing Comment

    I would much rather have been able to demonstrate what was broken and how it was fixed but sometimes, this time included, just finding *a* fix will suffice.  Hopefully this can be a light for someone else.

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