Techniques are described for using route target constraint to filter routes advertised to a node in a seamless Multiprotocol Label Switching (MPLS) network. For example, a first router of a first network may generate a first border gateway protocol (BGP) message to advertise routing information for a first node of the first network, the first BGP message indicating a transport class and specifying an address-specific route target, the transport class comprising one or more tunnels to the first node that share common characteristics. In response to receiving a second BGP message originated by second node of a second network, the second BGP message comprising the address-specific route target, the first router sends the first BGP message to a second router of the second network for sending to the second node to cause the second node to import the routing information.