Hi Couple of questions around macvtap direct usage: 1) is the document here current? https://libvirt.org/formatnetwork.html#examplesDirect

I have been able to get host to guest network traffic without any special configuration or switch since Fedora 28 when I first started using it. Using <forward mode=vepa> requires switch port mirroring, but just using <forward mode=bridge> doesn't.

2) do any of the language libraries make assumptions that libvirt networks must have a <bridge name=xx> attribute? Foreman's Ruby interface to libvirt errors out with attempting to build a VM on a KVM host with a network defined with <forward mode=bridge> https://projects.theforeman.org/issues/25890

Call to virNetworkGetBridgeName failed: internal error: network

On Thu, May 14, 2020 at 1:32 PM Laine Stump <laine(a)redhat.com <mailto:laine@redhat.com>> wrote: On 5/13/20 12:52 AM, Subhendu Ghosh wrote: > Hi > > Couple of questions around macvtap direct usage: > > 1) is the document here current? > https://libvirt.org/formatnetwork.html#examplesDirect Yes. None of that has changed in any major way in many years. kernelNewbies documents mactap bridge as VMs can host can all talk to each other without an external bridge

External bridge/switch is only needed for VEPA mode with hairpin.

https://virt.kernelnewbies.org/MacVTap Perhaps the original development of macvtap to support VEPA influenced the early docs and was never reviewed after bridge mode matured?

> > I have been able to get host to guest network traffic without any > special configuration or switch since Fedora 28 when I first started > using it. Using <forward mode=vepa> requires switch port mirroring, but > just using <forward mode=bridge> doesn't. If that is the case, then either your guest and host have a secondary network connection, or your switch is mirroring traffic and you just didn't know about it. The inability to do direct host<->guest communication is inherent in the design of macvtap interfaces. > > 2) do any of the language libraries make assumptions that libvirt > networks must have a <bridge name=xx> attribute? Foreman's Ruby > interface to libvirt errors out with attempting to build a VM on a KVM > host with a network defined with <forward mode=bridge> > https://projects.theforeman.org/issues/25890 The 2nd line in the log attached to that issue report says this:  >Call to virNetworkGetBridgeName failed: internal error: network 'macvtap-net' does not have a bridge name. So, your application (or whatever this "Foreman's Ruby interface to libvirt" is) has called virNetworkGetBridgeName() (whatever it's called in the Ruby bindings), and since you have a macvtap network, which has no bridge device, libvirt sent back an error. You need to find whatever in your code is calling virNetworkGetBridgeName().