Discovering a network service topology of a virtual private network (VPN) that uses multiprotocol label switching (MPLS) comprises receiving route target values from a virtual private network (VPN) route forwarding table (VRF table) of a networking device; determining and storing in a table one or more link pairs based on the route target values, wherein each of the link pairs indicates a connection between a first site and a second site within the VPN; creating a set of VPN objects based on an association between a first VPN object and the one or more link pairs stored in the table, wherein each of the VPN objects includes information indicating connectivity between a subset of sites from a plurality of sites within the VPN; and determining the topology for the first VPN object based on applying one or more topology rules to the subset of sites within the first VPN object.