Tracing VPLS Nonstop Active Routing Synchronization Events
To trace the label and logical interface association that VPLS
receives from the kernel replication state, include the nsr-synchronization
statement at the [edit routing-options traceoptions flag]
hierarchy level. This flag also traces the Layer 2 VPN signaling
state replicated from routes advertised by BGP.
[edit routing-options] traceoptions { flag nsr-synchronization; }