Re: duplicate MAC - Re: 13.1R problems on Pi3

From: Karl Denninger <karl_at_denninger.net>
Date: Tue, 05 Jul 2022 23:37:42 UTC
On 7/5/2022 19:34, bob prohaska wrote:
> On Tue, Jul 05, 2022 at 07:02:18AM -0700, Mark Millard wrote:
>
>>> So for you I would guess:
>>>
>>> ifconfig_ue0="ether ??:??:??:??:??:?? inet 50.1.20.28 netmask 255.255.255.0"
>   
> I tried a few variants, all produced a dead connection.
>
> Using  one like you suggested:
>
> # ethernet address increased by 1 in the last digit
> ifconfig ue0="ether b8:27:eb:71:46:4f inet 50.1.20.28 netmask 255.255.255.0"
>
> produced a flood of errors during boot:
> ifconfig: interface ue0=ether b8:27:eb:71:46:4f inet 50.1.20.28 netmask 255.255.255.0 does not exist
>
> There was clearly no network connectivity, but the serial console
> remained responsive. The host sharing the same MAC address exhibited
> no connectivity problems.
>
>
> Another suggestion was found in an old forum post, assigning the IP
> in the usual fashion but adding an alias:
>
> ifconfig_ue0="inet 50.1.20.28 netmask 255.255.255.0"
> ifconfig_ue0_alias0="link b8:27:eb:71:46:4f"
> (trading ether for link had no effect)
>
> resulted in the gateway (and everything else) being unreachable.
>
> Thanks for writing!
>
> bob prohaska

Crap - you have to see if you can get u-boot (e.g. in config.txt) to do 
it then.... that's not supposed to happen (manufacturing two devices 
with the same MAC address) and is EXTREMELY not-nice for the very reason 
you've discovered.  Linux's boot line has an override available for it, 
so there IS a way.

-- 
Karl Denninger
karl@denninger.net
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