Migrating ESX host and VMs from one Vcenter to another

[Gopi14]

I need to move few ESX hosts and its VMs from one Vcenter to another. I don't want to get a MAC address conflict for the new VMs creating in old Vcenter with VMs migrated to new Vcenter. What are the MAC prefix i can assign in old Vcenter other than default OUI 00:50:56.

My environment: Vcenter 5.1, ESXi 5.1 and Windows 2003 & 2008 VMs.

[vNEX]

Hi,

if your vCenter servers has different IDs you should not have any problems with MAC conflicts because when you are creating VMs through vCenter

autogenerated MAC address for the VM is based on vCenter ID. Respectively last three octets are based on vCenter unique ID.

Check it here:

vSphere Client, click Administration > vCenter Server Settings > Runtime Settings.

If your IDs are same you can safely change them. (vCenter restart is needed)

If you want to explicitly set custom prefixes instead of using VMware default OUI follow these steps:

Change to or Adjust Range- or Prefixed-Based Allocations in the vSphere Web Client

Regards,

P.

[Gopi14]

Hi,

But the migrated VMs will have the same MAC address as it was in OLD Vcenter (ex:- 00:50:56:AA:BB:CC), so the OLD Vcenter thinks that this MAC address is free and there is a possibility of assigning this same MAC address to newly creating VMs in OLD Vcenter.

Please see the below link which explains MAC address issue in detailed.

http://www.virtuallyghetto.com/2014/05/considerations-when-migrating-vms-between-vcenter-servers.htm...

[vNEX]

Hi,

first to minimize the risk of MAC duplicity (when you move VMs between vCenter servers) is to make sure your vCenter servers don have identical UIDs.

This is of course not 100% guarantee that both vCenter servers will produce VMs with unique MAC addresses. (but with our two vCenters it never happen to us...)

If you want to go for 100% for every new VM MAC adresses use Prefix-Based MAC Address allocation on both vCenters (old/new) this will prevent a possibility that

vCenter will assign same MAC for newly deployed VM.

So to suppress undesirable MAC duplicity I would proceed wit these steps:

1. Gather all MAC addresses on old and new vCenter servers

2. Compare them if some duplicity exist (if exists correct them by setting manual MAC)

3. Before migration on both vCenters set Prefix-Based MAC Address allocation

   - vSphere client-> Administration-> vCenter Server Settings -> Advanced Settings add two keys:

config.vpxd.macAllocScheme.prefixScheme.prefix

config.vpxd.macAllocScheme.prefixScheme.prefixLength

prefix and prefixLength determine the range of MAC address prefixes that newly added vNICs

have. prefix is the starting OUI of MAC addresses related to the vCenter Server instance, and prefixLength determines the length of the prefix in bits.

For example, the settings from the table result in vNIC MAC addresses starting with 00:50:26 or 00:50:27.

For more info see:

http://pubs.vmware.com/vsphere-55/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-55-network...

Check if your new range isn't in conflict with registered OUIs:

https://standards.ieee.org/develop/regauth/oui/oui.txt

4. Migrate appropriate VMs

Regards,

P.

[Gopi14]

Hi,

Sorry for the delayed reply..

Thanks for your response and as per the link "https://standards.ieee.org/develop/regauth/oui/oui.txt", i could see the below MAC prefix's are from VMware OUI but what is the alternate prefix that i can use in my Vcenter other than default OUI 00:50:56.

Also I can not find the correct details in internet and even in VMware portal that on which VMware products or Scenarios each of the below MAC prefix's are used ?

In my understanding, 00:50:56 is the default MAC range generated by Vcenter and 00:0C:29 generated for VMs created in standalone ESX host but no idea about others.

1) 00:50:56

2) 00:05:69

3) 00:0C:29

4) 00:1C:14

And again, finally i need a correct VMware OUI MAC prefix to use in my Vcenter other than default one.

Regards,

Gopi

[vNEX]

Hi Gopi,

as alternative use some custom range or value which will not interfere with any registered OUI  in IEEE org.

https://standards.ieee.org/develop/regauth/oui/oui.txt

They are all registered in IEEE by VMware, Inc.

1) 00:50:56 - auto generated MAC by vCenter server

2) 00:05:69 - probably auto-generated MAC on legacy ESX hosts

3) 00:0C:29 - auto generated MAC on ESXi hosts and products like VMware Workstation

4) 00:1C:14 - this could be reserved prefix for some future products ???