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Date:      Tue, 17 Jun 2025 18:57:23 +0200
From:      A FreeBSD User <freebsd@walstatt-de.de>
To:        Lexi Winter <ivy@freebsd.org>
Cc:        FreeBSD CURRENT <freebsd-current@freebsd.org>, net@freebsd.org
Subject:   Re: if_bridge(): IPv6 EUI-64 seemingly not working
Message-ID:  <20250617185750.55eba7e8@thor.sb211.local>
In-Reply-To: <aFGBMnDMMvVRlz94@freefall.freebsd.org>
References:  <20250611072836.2a0b026a@thor.sb211.local> <aEpQZgquqB8HolCn@freefall.freebsd.org> <20250612073301.60bfc7ce@freyja> <aFGBMnDMMvVRlz94@freefall.freebsd.org>

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Am Tage des Herren Tue, 17 Jun 2025 15:52:34 +0100
Lexi Winter <ivy@freebsd.org> schrieb:

> FreeBSD User:
> > net.link.bridge.inherit_mac: 1
> > [...]
> >=20
> >         ether 4c:52:62:2b:05:eb
> >         inet6 fe80::5a9c:fcff:fe00:393a%bridge0 prefixlen 64 scopeid 0x=
6 =20
>=20
> i was able to reproduce this:

First of all, thank you very much for checking this.

>=20
> # sysctl net.link.bridge.inherit_mac=3D1
> 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
>=20
> some observations:
>=20
> - i don't think this is caused directly by the member_ifaddrs changes.
>=20
> - 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
>=20
> - 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.

I'd dare to disaggree, we have running several recent CURRENT and 14-STABLE=
 boxes (almost
every 2nd day recompiled world/kernel) with very close configuration scheme=
s (according to
kernel config and NIC/bridge config as far it is possible to say so with re=
spect to the
different OS and different network addresses). On 14-STABLE with very simil=
ar jail
configuration I do NOT see this (mis)behaviour of if_bridge().=20


--=20

A FreeBSD user

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