Hi Dave, > So how exactly do the oversized packets get to the macvlan device from > the VM in this scenerio? That detail seems to be missing from the > diagrams you provided earlier. The VM and the macvlan boxes are just > connected with a line.
Inside the VM I'm using netperf talking on an interface which the guest believes to have a MTU of 1500. I'm setting up the VM using libvirt - my understanding is that libvirt creates a macvtap device in private mode, and qemu opens that tap device and writes data from the emulated network card (I see the same behaviour with a emulated rtl8139, e1000, and with virtio). I think I could replicate this with any userspace program - qemu is just the easiest for me at the moment. Hopefully that's what you had in mind? Let me know if you wanted different info. Regards, Daniel [The gory details, in case it matters: The VM has a network adaptor with the following XML: <interface type='direct'> <mac address='52:54:00:e7:a2:ac'/> <source dev='enx0050b6655ff2' mode='private'/> <model type='rtl8139'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/> </interface> ] > > Thank you.