I have read a few posts here on NOT using tagged vlans in KVM because of the emulated e1000 drivers, but I have a situation where I need to use tagged vlans. Because of this we used SR-IOV enabled machines and adapters since this allows us to install the full Virtual Function driver from Intel (and this allows our powershell/wmi scripts to manage the vlans).
I am not a KVM/Linux admin, I understand Windows and VMWare a lot more, but our linux guy who set this all up is no longer available and I have to figure out why we can't get tagged vlans to pass through the KVM bridges(yeah, I know, sr-iov means we should be completely bypassing bridges or vswitches and such… but I am not exactly sure how it works in KVM). Is there configuration that I need to change on the KVM hosts to allow the vlan tagging to pass through? I am willing to research but am not sure where to even start.
I willpost configurations and such as necessary, by request, to facilitate this discussion if tagged vlan support is actually something I can do in kvm.
Best Answer
Why not simply use virtio? e1000 is emulated, this is why virtio has been created in the first place.
So, if you simply need to have VLAN tagged traffic inside VMs, you simply tag it in the VMs. The common practice though, is to build the bridge on top of a tagged interface or bond on the host, and attach the VMs that need to be on that VLAN to that bridge.