In 6PE networking, the shared explicit null label function can be enabled on routers to reduce the number of required MPLS labels. With this function, a router assigns a label with the value (enter only digits) to all 6PE routes.

0In 6PE (IPv6 over MPLS for Provider Edge), the shared explicit null label value is 0. When this function is enabled, the PE router assigns label 0 (IPv4 Explicit Null) to all IPv6 routes, reducing the label space consumption. This is known as label 0 reuse for IPv6 forwarding over MPLS.Exact Extract - HCIE-Datacom IPv6/MPLS Integration Section:''To optimize label usage in 6PE deployments, shared explicit null label (label 0) can be assigned to all 6PE routes.''