OT alittle: Dual NIC's on K8N Neo2 MSI MB share Mac Addresses and more

[Bob Chiodini]

Scot L. Harris wrote:

>On Fri, 2006-01-06 at 12:49, Doug Coats wrote:
>
>  
>
>>different boards shared the same MAC.  So on the network I had 4 NICs
>>with the same MACs and two of them where on the same subnet.
>>
>>I figured out how to change the MAC that the eth was reporting in the
>>ifcfg-eth# file and the traffic issued resolved themselves.
>>
>>My questions are:
>>
>>Has anyone seen anything like this before?  I thought it was outside
>>of the networking standards to use the same MAC address on any two
>>machines in the world.  Am I missing something?
>>
>>    
>>
>
>Have heard of it before.  I forget the manufacturer but there was a
>batch of NICs that had similar problem many many years ago.  In the past
>there was a process to get MAC address blocks assigned to the company
>making the NICs.  I assume this is still in place.  In theory there
>should not be duplication of MAC addresses. 
>
>  
>
>>Do any of you for see problems using these NICs the way that I am?
>>    
>>
>
>Just keep track of what MAC addresses you have set and make sure they
>come up that way during reboot.
>
>For IPv4 there should not be any problems since the MAC address should
>not be passed outside of your LAN.  I don't even think this would cause
>any problems with IPv6 addressing.
>
>  
>
Doug,

I have seen this as well.  Have you upgraded the BIOS es lately?  There 
is an option to the BIOS updater that must be used to set the MAC 
address.  I cannot remember what it was, but invoking the update program 
with /? will tell you.

IIRC, one of the controller's MAC address is fixed while the other is 
set when the BIOS is loaded.  I cannot remember which is which, but eth1 
on my motherboard has the lower address, so I suspect that it has the 
fixed address.

There is a label on the motherboard with the original MAC address of the 
non-programmable controller.  I would add 1 and use the result for the 
programmable MAC address.

Bob...