Protocol used for service VLAN (default: 802.1ad) 802.1ad 802.1q 802.1ad Provider Bridging (IEEE 802.1ad, Q-inQ), ethertype 0x88a8 802.1q VLAN-tagged frame (IEEE 802.1q), ethertype 0x8100 (802.1q|802.1ad) Ethertype must be 802.1ad or 802.1q 802.1ad