[AusNOG] Internal use MAC addresses

[Mark Smith]

----- Original Message -----
> From: Wade Roberts <ausnog at acquired-taste.net>
> To: Geordie Guy <elomis at gmail.com>
> Cc: ausnog at lists.ausnog.net
> Sent: Saturday, 23 February 2013 9:36 PM
> Subject: Re: [AusNOG] Internal use MAC addresses
> 
> On 2013-02-23, at 20:27, Geordie Guy <elomis at gmail.com> wrote:
> 
>>  Hey folks,
>> 
>>  Is there a "555" style best practice for MAC addresses?  I'm 
> mucking around with programming electronics and writing Ethernet bits and pieces 
> and while it's commonplace for me to hardcode 192.168.0/24 addresses to 
> projects, I also need to code MAC addresses.  Is there an OUI equivalent of 
> 172.16/192.168/10.?  or does nobody care because it's not relevant outside a 
> layer 2 domain...
>> 
>> 
>>  - Geordie
>>  _______________________________________________
>>  AusNOG mailing list
>>  AusNOG at lists.ausnog.net
>>  http://lists.ausnog.net/mailman/listinfo/ausnog
> 
> 
> 2 Options:


The following is not a good idea, as that list doesn't include all OUIs (you can pay a fee to have them kept private), and it is a bad idea to steal unused public addresses (in any space, both layer 2 and layer 3).

Here is an example of why:

http://www.gossamer-threads.com/lists/nanog/users/138680


The first hand story I heard about somebody suffering from the above story was that they'd got to the point of replacing the entire blade chassis to try to resolve the problem. Blade chassis replacement is a lot of work, and in the particular facility it was in, would have involved lots of change management etc. - all for naught (IIRC, they'd been trying to resolve this problem for more than a week). Some developer got lazy and decided to steal an public unused IP addresses, and then incurred probably 1000s of hours of troubleshooting effort globally. A short cut for you may be a long cut for somebody else (and given the type of problem you're causing, it might be a long cut with a cut throat razor.)

> 1: Pick anything not allocated here: 
> http://standards.ieee.org/develop/regauth/oui/oui.txt
> 
> 2: Make one up, set the 7th bit (see U/L or X bit) to 1 to make it local only.


This is what to do. However, get a proper OUI or IAB if your product is going to be able to be used on other people's networks.

Here's how to get an 22 bit OUI, and how much it costs:

http://standards.ieee.org/develop/regauth/oui/index.html


I don't know much about IABs, however they seem to be a cheaper way of having globally unique MAC addresses if you don't need as many addresses as an OUI would provide:

http://standards.ieee.org/develop/regauth/iab/index.html


Don't do what Microsoft and others have done - keep what should be private private.


http://mailman.nanog.org/pipermail/nanog/2008-November/005530.html