superfluous host interfaces

Julian Elischer julian at
Tue Feb 27 21:11:51 UTC 2018

On 26/2/18 6:34 pm, Ruben wrote:
> 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.
I will add another postive to ng_bridge and a negative..
using ng_bridge makes it easier to do funk things with your network if 
you want to
but it requires you to do your own scripting.

see the jail examples in /usr/share/examples and replace the jail with 
> Kind regards,
> Ruben
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