vCloud restore - MAC conflict

[JeroenD]

Hi,
we are using Veeam v7 patch1 to backup VM's on vCloud Director 5.1 and we have been testing some restores which caused us headaches.

We restore a VM from, let's say organization A, to another organization (let's call it B) which uses another VLAN. We thought that this way, we can test restores without causing IP conflicts with the original machine.
That seemed to go okay until we heard organization A complain they couldn't reach a server...and that server was the one we restored to organization B in that other VLAN.
Pinging to that server resulted in succes, failure, failure, succes, ...so very bad...but it all worked again when we turned off our restored VM.
So there must've been a conflict! Then we checked settings and saw that the restored VM used the same MAC address as the original VM which is actually normal....but we never thought this would cause a conflict because we use VLAN's.

Our resource cluster that vCloud controls uses a distributed switch with VLAN's per Organization. Is that the reason that we had this issue? I don't really understand as we use seperate VLAN's which is a layer 2 separation at the same level as MAC addresses.
So I want to warn anyone doing test restores of vCloud VM's to other organizations thinking that won't cause conflicts. You have to change the MAC before booting them up.
I wish the Veeam restore wizard would have warned me for this.

I suppose this is a VMWare issue... but it would be nice to have some warnings in Veeam.

How would you recommend doing test restores of VM's in vCloud?

Regards,
J

[dellock6]

You are correct that VLAN is a Layer2 construct, but nonetheless the duplicated MAC addresses are going to be recorded in the same table of a given switch, the problem is not the vlan itself but the switch that sees two mac addresses and (depending on the switch model) it has problem deciding at which mac address it has to forward packets. I've seen this problem first hand a couple of times.
Lan segmentation is made to "fence" IP addresses, not mac addresses.

Not sure why you are having duplicated mac address, since a cloned VM has a new mac address, unless you had a fixed mac address when you first created the VM...

Luca.

[tsightler]

Not sure why you are having duplicated mac address, since a cloned VM has a new mac address, unless you had a fixed mac address when you first created the VM...

vCloud Director uses it's own formula for managing MAC addresses so whenever a VM created with/imported into vCD it will pretty much always have a "manual" MAC address setting from the vSphere perspective. Veeam restores the VM exactly as it was when it was backed up, including this manual MAC configuration.