First a basic unit of VPN information is defined, followed by actions performed on this unit. Combination of all the sets would then represent the entire VPN information for a given CE-ID of a VPN on a PE router. They must never overlap. The VPN information set is either active or inactive. Active state means that label resources have been allocated and the VPN information set has been advertised.
Inactive state indicates existence of the set without label allocation and unadvertised status.
An active set becomes inactive when VPN information of the set is withdrawn. The VPN information set is considered activated when a range of labels are allocated for the set. If the set consists of more than one fragment, all the fragments must be advertised before the set is considered active. The set is activated under following circumstances. A set matching the local CE-ID 2.