SRIOV bypasses vrouter for passthrough networking
SR-IOV or sriov interfaces have both physical functions (PFs) and multiple virtual functions (VFs).
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https://www.juniper.net/documentation/en_US/contrail4.0/topics/concept/sriov-with-vrouter-vnc.html
virtio
- The host implementation is in userspace - qemu, so no driver is needed in the host.