netdev - Re: [Discuss] IPv4 packets lost with macvlan over bond alb

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Date: Sat, 17 Jun 2023 16:29:06 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: Jay Vosburgh <jay.vosburgh@...onical.com>
Cc: netdev@...r.kernel.org
Subject: Re: [Discuss] IPv4 packets lost with macvlan over bond alb

On Sat, Jun 17, 2023 at 9:45 AM Jay Vosburgh <jay.vosburgh@...onical.com> wrote:
>
> Hangbin Liu <liuhangbin@...il.com> wrote:
>
> >Hi Jay, any thoughts?
>
>         Just an update that I've done some poking with your reproducer;
> as described, the ARP reply for the IP address associated with the
> macvlan interface is coming back with the bond's MAC, not the MAC of the
> macvlan.  If I manually create a neighbour entry on the client with the
> corrent IP and MAC for the macvlan, then connectivity works as expected.
>
>         I'll have to look a bit further into the ARP MAC selection logic
> here (i.e., where does that MAC come from when the ARP reply is
> generated).  It also makes me wonder what's special about macvlan, e.g.,
> why doesn't regular VLAN (or other stacked devices) fail in the same way
> (or maybe it does and nobody has noticed).

VLAN or other overlay devices use the same MAC address with Bonding.
So they work with the alb mode. But MACVLAN uses different MAC
addresses with Bonding.

Thanks
Hangbin