* OVS_KEY_ATTR_ENCAP 0 -- 4 4 (VLAN encapsulation)
* OVS_KEY_ATTR_ETHERTYPE 2 2 4 8 (inner VLAN ethertype)
* OVS_KEY_ATTR_IPV6 40 -- 4 44
* OVS_KEY_ATTR_ICMPV6 2 2 4 8
* OVS_KEY_ATTR_ND 28 -- 4 32
* ----------------------------------------------------------
* OVS_KEY_ATTR_ENCAP 0 -- 4 4 (VLAN encapsulation)
* OVS_KEY_ATTR_ETHERTYPE 2 2 4 8 (inner VLAN ethertype)
* OVS_KEY_ATTR_IPV6 40 -- 4 44
* OVS_KEY_ATTR_ICMPV6 2 2 4 8
* OVS_KEY_ATTR_ND 28 -- 4 32
* ----------------------------------------------------------