• Esxi Manual Mac Address Range Lookup
• Esxi Manual Mac Address Ranger
• Esxi Manual Mac Address Range Calculator

• Apr 08, 2012  How to maintain a the same MAC address all the time within your vSphere 4 installation. In VMware vSphere 4 environement, when you move your VM to another host or the VM has different path on the same host, the MAC adress of the VM is changed. If you want to guarantee that the same MAC address is.
• The maximum value for a manually generated MAC address is shown in the sample. Ethernet.address = 00:50:56:3F:FF:FF. You must also set the address type in a virtual machine’s configuration file. Ethernet.addressType='static' Because ESXi virtual machines do not support arbitrary MAC addresses, you must use the example format.

Assign a static MAC Address in the vSphere Client. In the MAC Address group, select Manual. Enter the static MAC address, and click OK.

I want to assign my virtual machines MAC addresses so that I can configure DHCP reservations for them so that they always get the same IP address regardless of which host hypervisor they are running on or operating system they are running.

What I need to know is what range of MAC addresses can I use without fear that one day some device may be connected to our network with that MAC?

I have read the Wikipedia article on MAC addresses and this section seems to indicate that if I create an address with the form 02-XX-XX-XX-XX-XX then it is considered a locally administered address.

I would assume this means that no hardware manufacturer would ever use an address starting with 02 so I should be safe to use anything that starts with 02 for my virtual machines?

Thanks for the help.

Chris MagnusonChris Magnuson

6 Answers

There are actually 4 sets of Locally Administered Address Ranges that can be used on your network without fear of conflict, assuming no one else has assigned these on your network:

Replacing x with any hex value.

Sam CoganSam Cogan

The complete list of assigned mac prefixes can be found here:http://standards.ieee.org/regauth/oui/oui.txt

There are several prefixes marked private on that list, 02 is not one of them. If you use one of those, you should be relatively safe. Keep in mind that other devices, software, etc. may also use that prefix, in which case your chance of a conflict goes up slightly.

If you are using randomly generated suffixes, your odds of collision are pretty astronomical.

Paul McMillanPaul McMillan

In case you are using VMware products (ESXi / Workstation / vCenter / ...), the valid range of manually assigned MAC addresses is:

For Xen virtual machines you can use anything starting with 00:16:3E, and that's the default which many management tools will generate.

Kamil KisielKamil Kisiel

I know this is old, but the way I read this is like so (as I am doing this now for Hyper-V 2012 and in an MSP environment....)

The order of the Hexadecimal digits is transmitted in pairs in reverse order on the ethernet wire.Thus, A3:xx:xx:xx:xx:xx is transmitted as 1100 0101:xx:xx:xx:xx:xxThe 3 is transmitted before the A, making the two least significant bits transmitted first both 1's. This is according to http://standards.ieee.org/develop/regauth/tut/macgrp.pdf

Therefore, it appears that the above is correct. I understand the wiki article referenced above as well, but believe 06 is a poor example and not the way the bits are transmitted on the wire.
Here is a screen capture of the relevant piece of the above linked PDF:

This would make the ranges start as follows for Unicast:x2:, x6:, xA:, xE:And as follows for Multicast:x3, x7,xF.

It seems Virtualbox version 5 uses locally administered addresses beginning with 0A-00-27 ( while in previous versions it was using 08-00-27 ).

By the way when assigning MAC addresses manually just keep in mind that 00-03-FF is used by Virtual-PC VMs like mentioned here:http://blogs.technet.com/b/medv/archive/2011/01/24/how-to-manage-vm-mac-addresses-with-the-globalimagedata-xml-file-in-med-v-v1.aspxand 00-15-5D is used by Hyper-V VMs like mentioned here:http://technet.microsoft.com/en-us/library/jj590655.aspx

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Features | Documentation | Knowledge Base | Discussion Forums

Maintaining and Changing the MAC Address of a Virtual Machine

When a virtual machine is powered on, VMware Workstation automatically assigns each of its virtual network adapters an Ethernet MAC address. MAC stands for media access control. A MAC address is the unique address assigned to each Ethernet network device.

The software guarantees that virtual machines are assigned unique MAC addresses within a given host system. In most cases, the virtual machine is assigned the same MAC address every time it is powered on, so long as the virtual machine is not moved (the path and filename for the virtual machine's configuration file must remain the same) and no changes are made to certain settings in the configuration file.

In addition, VMware Workstation does its best, but cannot guarantee, to automatically assign unique MAC addresses for virtual machines running on multiple host systems.

Avoiding MAC Changes

To avoid changes in the MAC address automatically assigned to a virtual machine, you must not move the virtual machine's configuration file. Moving it to a different host computer or even moving it to a different location on the same host computer changes the MAC address.

You also need to be sure not to change certain settings in the virtual machine's configuration files. If you never edit the configuration file by hand and do not remove the virtual Ethernet adapter, these settings remain untouched. If you do edit the configuration file by hand, be sure not to remove or change the following options:

ethernet[n].generatedAddress
ethernet[n].addressType
ethernet[n].generatedAddressOffset
uuid.location
uuid.bios
ethernet[n].present

In these options, [n] is the number of the virtual Ethernet adapter, for example ethernet0.

Note: To preserve a virtual Ethernet adapter's MAC address, you also must be careful not to remove the adapter. If you remove the adapter, then recreate it, the adapter may receive a different MAC address.

Manually Assigning a MAC Address

Esxi Manual Mac Address Range Lookup

If you want to guarantee that the same MAC address is assigned to a given virtual machine every time, even if the virtual machine is moved, or if you want to guarantee a unique MAC address for each virtual machine within a networked environment, you can assign the address manually instead of allowing VMware Workstation to assign it automatically.

To assign the same, unique MAC address to any virtual machine manually, use a text editor to remove three lines from the configuration file and add one line. The configuration file has a.vmx extension at the end of the filename. On a Linux host, a virtual machine created with an earlier VMware product may have a configuration file with a .cfg extension.

Esxi Manual Mac Address Ranger

Remove the three lines that begin with the following from the configuration file:

ethernet[n].generatedAddress
ethernet[n].addressType
ethernet[n].generatedAddressOffset

In these options, [n] is the number of the virtual Ethernet adapter — for example ethernet0.

Add the following line to the configuration file:

ethernet[n].address = 00:50:56:XX:YY:ZZ

In this line, XX must be a valid hexadecimal number between 00h and 3Fh, and YY and ZZ must be valid hexadecimal numbers between 00h and FFh. Because VMware Workstation virtual machines do not support arbitrary MAC addresses, you must use the above format.

Esxi Manual Mac Address Range Calculator

So long as you choose a value for XX:YY:ZZ that is unique among your hard-coded addresses (where XX is a valid hexadecimal number between 00h and 3Fh, and YY and ZZ are valid hexadecimal numbers between 00h and FFh), conflicts between the automatically assigned MAC addresses and the manually assigned addresses should never occur.