[U-Boot-Users] Valid EMAC address

[Ben Warren]

Mathieu,

I know Wolfgang has already answered, and the answer is indeed in the
FAQ.  There is a lot of other good info there that you should see.
Anyway, when assigning a MAC, there are a couple of bits that it's
always good to know about:

bit 40 (01:00:00:00:00:00) indicates a multicast address.  This should
never be set on your primary listening address.  Depending what
protocols you're using, there may be several multicast addresses that
you listen on, but you should never program this yourself.

bit 41 (02:00:00:00:00:00) indicates that this is a private address.
You should never ship a product that has this bit set if it is to
interface with a public network (i.e. one containing devices by other
manufacturers), but you are free to set it for internal use.  

To be safe, I always use 02:00:xx:xx:xx:xx in the lab and then buy a
range of unicast addresses from IEEE for shipping product.  Here's where
you get them:

http://grouper.ieee.org/groups/msc/MSCRacInfo/FAQ%20Registration%
20Authority%20Revised.htm

regards,
Ben

ou are proOn Mon, 2006-03-27 at 10:01 +0200, Mathieu Deschamps wrote:
> Hello ,
> 
> I've just found that an invalid EMAC address -I guess-  I've given to test,  
> was the reason for all NET_COMMANDS (ping, tftpboot and the like) to gently 
> fail without any errors whereas NET_DEBUG and ET_DEBUG were definied.
> 
> Indeed, I've change supposed invalid addr 47:55:47:55:47:55:aa to
> 12:43:56:78:90:aa and it worked. So here I come and apolozige in advance
> if somebody already answered theses, I haven't found anything relevant in
> archives  :
> 
> How to determin if a EMAC is valid/legal ? Why u-boot doesn't implement 
> such a validiy test -at least when debugging is defined- in order to defeat 
> that strange developper reflex, looking for _the_ inexisting bug ?
> 
> 
> 
> Best Regards,
>  
> Mathieu Deschamps
> 
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> Com2gether Design Center
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