What term describes loss of MPLS labels and inner VPN information when a packet traverses an untagged interface, breaking VPN connectivity?

A "black hole" in MPLS VPNs refers to the scenario where a packet loses its MPLS labels and inner VPN information when it egresses an untagged interface. This typically happens when a router receives a labeled packet but forwards it out an interface that is not configured to handle MPLS, or when a router in the path is not MPLS-aware. The packet effectively disappears from the VPN, as subsequent routers cannot identify its VPN context, hence the term "black hole." Pseudowire is a technology for emulating a point-to-point connection over a packet-switched network, not a problem description. Traffic Engineering is a method for optimizing network resource utilization. Active Network Abstraction is a concept related to network programmability, not a specific problem like this.