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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.

stukelly
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Chris Magnuson
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6 Answers6

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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:

x2-xx-xx-xx-xx-xx
x6-xx-xx-xx-xx-xx
xA-xx-xx-xx-xx-xx
xE-xx-xx-xx-xx-xx

Replacing x with any hex value.

Andy Finkenstadt
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Sam Cogan
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13

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

00:50:56:00:00:00 - 00:50:56:3F:FF:FF
Jossef Harush Kadouri
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geeklin
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12

The complete list of assigned mac prefixes can be found here:

http://standards-oui.ieee.org/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 McMillan
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6

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.aspx and 00-15-5D is used by Hyper-V VMs like mentioned here: http://technet.microsoft.com/en-us/library/jj590655.aspx

zdzich
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5

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 Kisiel
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5

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:xx The 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: enter image description here

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

Thomas Mekeel
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