Enhanced Y.1731 functionality on VPWS to support ETH-LM for dual VLAN tags

Junos OS supports Ethernet frame loss measurement (ETH-LM) between maintenance association end points (MEPs) configured on Ethernet physical or logical interfaces on Rev-B Dense Port Concentrators (DPCs) in MX Series routers. Additionally, the Y.1731 functionality supports ETH-LM only for an end-to-end connection that uses Virtual Private Wire Service (VPWS). Prior to this Junos OS Release, this functionality did not support ETH-LM for dual VLAN identifier tags. It only supported ETH-LM for untagged or single VLAN identifier tags. Now, the Y.1731 functionality supports ETH-LM on VPWS for dual VLAN identifier tags as well.