1b- SRIOV bypasses vrouter for passthrough networking
SR-IOV or sriov interfaces have both physical functions (PFs) and multiple virtual functions (VFs).
Intel SR-IOV Explanation:
The main idea is to bypass the work ( interruption) and moves of packet received in the NIC >>>> the SR-IOV capable NIC will move ( CPU) the packet to a vMemory of the VNF: no involvement of the sw/interuption
https://www.juniper.net/documentation/en_US/contrail4.0/topics/concept/sriov-with-vrouter-vnc.html
virtio: https://wiki.libvirt.org/page/Virtio
virtio like vmxnet3 and xenvirt are part of the DPDK stack
So-called "full virtualization" is a nice feature because it allows you to run any operating system virtualized.
However, it's slow because the hypervisor has to emulate actual physical devices such as RTL8139 network cards .