Re: Initial development for veb(4), a lightweight Ethernet bridge for bhyve and vnet jails

On 21.09.26 22:02, Aaron Espinoza wrote:
> Hello net@,
>
> I'm Aaron Espinoza, a 2025 GSoC participant. This past summer, I 
> worked on an initial veb(4)-style driver for FreeBSD, and I'd 
> appreciate some feedback from the community.
>
> Inspired by OpenBSD's veb(4), veb is a stripped L2 bridge aimed at 
> bhyve and vnet jail topologies. It’s not meant to replace 
> if_bridge(4). It leaves out features such as STP and pfil, and handles 
> host membership through a dedicated vport interface.

Nice project. I've been bitten by if_bridge(4) more then once through 
the years. It's just too easy to "hold it wrong". I agree demoting the 
members from in theory usable network interface to just bridge ports 
without IP addresses and splitting the bridge from the host port on it a 
much cleaner design.

> Code and docs: https://github.com/Acesp25/freebsd-veb
>
> docs/overview.md is the best starting point for why this driver was 
> created, and docs/design.md lists each design decision with its 
> rationale.
>
> I'll be presenting this work at the Fall 2026 Vendor Summit and would 
> value the list's feedback beforehand, particularly on:
>  - whether this work belongs in the src
>  - the implemented approach for vport explicit host membership
>  - anything in the design that may look wrong
>  - what the best practices are for creating benchmarks against 
> if_bridge(4) 

The limitations you accepted make sense to get the driver into a working 
state.

In my opinion VLAN filtering and spanning tree are not just nice to have 
even if you should disable them for the usecases you mentioned (vnet 
jails, bhyve guests) to avoid the delay until it becomes a forwarding 
access port.