MAC Address changes.

[vijayrana968]

So I am about to migrate bunch of servers to from old vcenter to new. I will clone those servers and after mounting old lun to new esxi hosts on new vCenter I am gonna select 'I have moved this vm' for migrated cloned VMs. Since the new MAC will already generated on existing vCenter where I will do cloing...My question is.

Do I need to change MAC address to existing one (generated on cloned VMX on old vcenter) before registering on new vCenter ? I am going to check with application vendor if application is MAC aware. along side this I also want to check that is it mandatory to change it existing one for OS network connectivity or the new assigned MAC will work !

[GPVenkatesh]

Hi vijayrana968

What is the version of your old and new vCenter ? If there is no change in vCenter versions & the licensing available is above enterprise plus, you may try using vSphere replication solution for smooth VM migration across vCenter with no MAC change.

Thank you.

[hussainbte]

Cloning the VM assigns the destination VM with new Mac.. for obvious reasons that you dont want 2 VMs with same MAC.

You can do storage vMOtion if you are migrating storage..

[vijayrana968]

So the cloned VMs would be migrating with storage to new vCenter which so changed MAC address isn't issue since it will be in new vCenter. Also the souce VLANs also available at new vCenter so no need to change IPs as well. I am concerned at OS level whether it will accept new MAC address for Network connectivity ?

[GPVenkatesh]

Hi -

From guest OS standpoint,

If  you have static IP allocation - You may end up in situation to reassign the IP address due MAC change.

If you have DHCP enabled segments, it may pick new IP due to MAC change.So here IP to MAC reservation have to be done from DHCP end.

[vijayrana968]

Yes, IPs are static so i will have to reassign IP manually but question is...do I need to keep changed MAC address or should modify it to the existing one where I will clone from.

[hussainbte]

Please take a look at below link for Migrations accross vCenters.

I believe all he required info is in there.

If you have enterprise plus licenses this is the best approach

Requirements for Migration Between vCenter Server Instances

MAC Address Management During Migration Between vCenter Server Systems

[hussainbte]

dont forget the vcenter version while checking the details

[vijayrana968]

So its not a vCenter to vCenter migration as these are separate vCenters and in linked mode.

What I am gonna do.

1. Provide new lun to existing hosts on existing vCenter.

2. Format with VMFS, and clone those VMs on newly formated datastore(which will change MAC on Power off Cloned VMs).

3. Present that VMFS datastore/LUNs to new host on new vCenter.

4. Register VMs on new vCenter.

So VMs at first stage have unique MAC which will be changed on Cloned VMs. Now Should I use the :

1. Cloned VMs MAC ?

2. MAC on original VMs ?

3. Or the new which will be assigned by new vCenter ?

[aadi369]

What are the OS running inside the Clone VM????????????

[vijayrana968]

These are 15 VMs mixture of RHEL, Oracle enterprise Linux and Windows.

[aadi369]

try to clear persistent entry from guest os level and reboot the VM. It will keep latest MAC address and clear all old MAC which were assigned from older host.

Jst for the reference :-

linux kernel - How to remove /etc/udev/rules.d/70-persistent-net.rules CentOS - Unix & Linux Stack Exchange

Need to run Sysprep to clear old MAC address persistent entry and old SSID's.

----------------------------------------------------------------

If it is useful, plz mark answer as correct or helpful.

----------------------------------------------------------------

[vijayrana968]

How about Windows VMs ?

[aadi369]

Need to run Sysprep to clear old MAC address persistent entry and old SSID's.

----------------------------------------------------------------

If it is useful, plz mark answer as correct or helpful.

----------------------------------------------------------------

[vijayrana968]

Okay, I will check it and let you know.