We have tested the EVPN-VPWS Layer 2 attribute last year. We continued testing this feature on the VPLS service this year. RFC 7432bis defined 3 Layer 2 attributes: Control Word, Flow Label, and Maximum Transmission Unit (MTU). Control word is for packet misordering. Flow label adds entropy to divisible flows, enabling effective ECMP load balancing across the network. And MTU is used to exchange MTU between the same Broadcast Domain (BD) located behind different PEs.
This time, the Layer 2 attribute extended community is advertised along with EVPN RT-3 in VPLS service, whereas RT-1 is used in VPWS service. We verified the control-word-mismatch and control-word-match scenarios with unicast traffic under the VPLS service this year. When the control word mismatched, all traffic was dropped; when matched, all traffic flew without loss.