superfluous host interfaces

Ruben mail at
Mon Feb 26 10:35:01 UTC 2018

On 26/02/2018 10:56, Harry Schmalzbauer wrote:

>> Hi Harry,
>> What are your reasons for preferring ng_bridge over the "normal" bridge?
> Two very different main reasons:
> if_bridge(4) is very standards compliant (e.g. that different reserved
> MAC addresses won't get forwarded – don't know any explicit examples out
> of mind), which was problematic for some SDN setups (software defined
> networking, in means of sharing a PHY for multiple VMs and
> simultaniously interconnect VMs to VMs)
> Another, personally very significant, reason is that you'll get a
> superfluous host interface for each if_bridge(4), which makes the output
> of plain ifconfig(8) kind of unreadable.
> For VM SDN, I don't need/want those host interfaces, despite they don't
> do any harm.
> vale(4) was extremely convinient.  Simply create a switch, then each VM
> attaches on the fly :-)
> Unfortunately, I'm unable to debug the lockups and my setups was kind of
> hacky, since I haven't used NIC's native netmap(4) support, but used
> emulated netmap(4) for if_vlan(4).  This leads to loss of almost all
> performance advantages, but left convinience advantages.  Unfortunately,
> emulated netmap(4) is supposed to have some unresolved problems on
> FreeBSD and upstream hackers consider my hacky setup as wrong by nature
> – which it is technically speaking.  For real-world usagen, one would
> need to code a VLAN filter between bhyve(4) and vale(4). Skillwise, I'm
> not the one :-(
> -harry
Hi Harry,

Thank you for elaborating on that. I took the liberty of creating a new
mailthread as my questions are kind of off-topic to the original thread.

By superflous host interfaces, do you mean the tap interfaces configured
for each vm together with the bridge interfaces they are "bundled" in?

Overall I'm very happy with my bhyve setups atm. If there are any
speed-/administrative-advantages that come with bridge_ng however, I'm
very interested in switching to such a setup (or at least play with it).
I'm running my vm's without any helper project so I'm flexible enough to
do some fiddling :P

Do you know of any documentation on using bridge_ng together with bhyve?
My search-engines don't turn up much Im affraid and I haven't stumbled
on it before.

Kind regards,


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