This boolean switch controls whether the router will emit SNMP traps (cpwVcUp and cpwVcDown) whenever this specific pseudowire transitions state, as opposed to requiring a management station to keep polling cpwVcOperStatus to notice the change. Enabling it on business-critical pseudowires, like a customer's primary MPLS L2VPN circuit, lets NOC alerting fire within seconds of a failure instead of waiting for the next poll cycle. If this is left at false(2) on a VC, an outage could go unnoticed for however long the polling interval is, since no trap will be sent regardless of how often the VC flaps.