From: Kapetanakis Giannis <bilias@edu.physics.uoc.gr>
Subject: Re: trunk(4): deprecate LACP mode
To: tech@openbsd.org
Date: Wed, 3 Dec 2025 14:59:17 +0200


On 02/12/2025 09:14, David Gwynne wrote:
> aggr(4) is a better option for LACP for several reasons:
>
> - in my experience aggr is better at following the standard
>
> it doesn't get into weird states that blackhole traffic at the worst
> possible times.
>
> - aggr is mpsafe
>
> the last time i looked at trying to make the lacp code mpsafe in
> trunk(4) i ended up writing aggr(4). this lack of mpsafety is now
> making it hard to unlock more of the network stack.
>
> - aggr is faster than trunk
>
> looking at the benchmarking we did when i first introduced aggr,
> it looks like using trunk(4) more than halved the pps you can
> forward through a box, while aggr was more like a 10 to 15% hit.
> switching from trunk to aggr in our environment doubled our firewall
> performance.
>
> apart from these implementation differences, there's a few operational
> ones too that sthen@ has pointed out:
>
> - aggr uses a random MAC by default, trunk uses the MAC of the first-
>   added child port.
>
> - aggr does not bring the interface up automatically, you must use "up".

How about failover mode on trunk? 

Is that mpsafe? Are there plans for this?

Thanks,

G