openstack team mailing list archive

[Brad McConnell <bmcconne@xxxxxxxxxxxxx>]

We (Rackspace) ended up acquiring a globally unique OUI for our public cloud, but to be honest I don't believe most users will need to go down this road.  It's only really necessary if you expect to do L2VPNs to other clouds, both use private mac ranges, and you expect them to overlap.  Pretty low odds.

We integrate this range through Melange which treats the mac range much like a 48-bit CIDR-able hex field so that we can delegate an arbitrary amount of contiguous bits to any given melange instance.  

To me, a global range that everyone is using that's provided by OpenStack is seems much worse than just calculating an arbitrary private range by flipping bit b2 to 1 as shown in the wiki article below.  As long as you set this, you're guaranteed not to collide with any registered mac OUIs from other vendors (assuming you generate a fairly random range with the remaining bits) and offer a reasonable guarantee of uniqueness if you end up integrating at L2 with other clouds.  If, however, many OpenStack clouds end up using the same OUI because the foundation globally registers one, your risk of collision during L2VPN between OpenStack clouds would be higher.

http://en.wikipedia.org/wiki/MAC_address

Just my two cents.. personally even if the foundation had a range I'd feel safer on a private scope than one that I KNOW a bunch of other clouds are using.

Thanks!

Brad McConnell
Rackspace network guy

________________________________________
From: openstack-bounces+bmcconne=rackspace.com@xxxxxxxxxxxxxxxxxxx [openstack-bounces+bmcconne=rackspace.com@xxxxxxxxxxxxxxxxxxx] on behalf of Eric Windisch [eric@xxxxxxxxxxxxxxxx]
Sent: Saturday, October 20, 2012 2:54 PM
To: Salvatore Orlando
Cc: Vinay Bannai; openstack@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Openstack] Use of MAC addresses in Openstack VMs

Sent from my iPad

On Oct 20, 2012, at 10:19, Salvatore Orlando <sorlando@xxxxxxxxxx> wrote:

> I understand your concerns about conflicts with already assigned OUIs.
> It is however my opinion that it is not up to the Openstack Foundation, but to entities deploying Openstack, to buy MAC OUIs.

For comparison and reference, Xen has its own OUI which is used by default for its VMs.  Users of Xen do not need to apply for their own OUIs and I don't believe they should.

It isn't necessary for VMs to have globally unique MACs, but they shouldn't overlap with devices from other vendors.

I believe OpenStack should have its own OUI.

Regards,
Eric Windisch
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