I am trying to understand KVM networking a little better and have noted that the "virbr0" network interface (the default KVM bridge) comes with another device named "virbr0-nic". The same kind of pair comes with each new bridge you may create via the "virtual machine manager" (and assumingly other KVM tools alike) Like "virbr1" comes in a pair with "virbr1-nic" (the *-nic interface is being created automatically (and I assume will disapear automatically if you remove the parent interface) Can anybody kindly explain how these pairs are related to each other and/or work together? thanks ... Gunnar
Daniel P. Berrangé
2021-Jan-04 11:20 UTC
relation between "virbr0" / "virbr0-nic" network interfaces
On Fri, Jan 01, 2021 at 10:24:41AM +0100, vrms wrote:> I am trying to understand KVM networking a little better and have noted > that the "virbr0" network interface (the default KVM bridge) comes with > another device named "virbr0-nic". > The same kind of pair comes with each new bridge you may create via the > "virtual machine manager" (and assumingly other KVM tools alike) > Like "virbr1" comes in a pair with "virbr1-nic" (the *-nic interface is > being created automatically (and I assume will disapear automatically if > you remove the parent interface) > > Can anybody kindly explain how these pairs are related to each other > and/or work together?The "$FOO-nic" device is a tap device created as a hack to force a stable MAC address on the main bridge device due to bad kernel impl of bridge device MAC address assignment. We stopped creating the "$FOO-nic" device in libvirt 6.8.0 since the kernel was long ago fixed. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|