Re: if_bridge(): IPv6 EUI-64 seemingly not working

On Tue, 17 Jun 2025 15:52:34 +0100
Lexi Winter <[email protected]> wrote:

> FreeBSD User:
> > net.link.bridge.inherit_mac: 1
> > [...]
> > 
> >         ether 4c:52:62:2b:05:eb
> >         inet6 fe80::5a9c:fcff:fe00:393a%bridge0 prefixlen 64
> > scopeid 0x6  
> 
> i was able to reproduce this:
> 
> # sysctl net.link.bridge.inherit_mac=1
> net.link.bridge.inherit_mac: 0 -> 1
> # ifconfig bridge1 create inet6 -ifdisabled auto_linklocal up
> # ifconfig bridge1 | egrep 'ether|inet6'
> 	ether 58:9c:fc:10:43:03
> 	inet6 fe80::5a9c:fcff:fe10:4303%bridge1 prefixlen 64 scopeid
> 0xa # ifconfig epair create
> epair2a
> # ifconfig bridge1 addm epair2a
> # ifconfig bridge1 | egrep 'ether|inet6'
> 	ether 02:36:0f:34:6b:0a
> 	inet6 fe80::5a9c:fcff:fe10:4303%bridge1 prefixlen 64 scopeid
> 0xa
> 
> some observations:
> 
> - i don't think this is caused directly by the member_ifaddrs changes.
> 
> - you can work around the problem by manually setting the bridge link
>   address when creating it instead of using inherit_mac, i.e.:
> 	  ifconfig bridge1 create link 02:00:00:00:00:01

Confirmed: this workaround, in rc.conf represented via
create_args_brisgeX="ether XX:XX:XX:XX:XX:XX"
sets linklocal adress according the inherited/forced MAC address and
later on via rtsol set the EUI64 host portion correct  as desired (on
CURRENT, not workaround needed on recent 14-STABLE, as reported).

> 
> - i don't think this is a bug per se, it's more that we simply don't
>   update the IPv6 lladdr when an interface's MAC address changes.
>   but i've copied net@ in case anyone else has an opinion on this.