Route target constraint to filter routes advertised to a node in a seamless mpls or seamless sr network

A method comprising:

• sending, by a first node of a first network and to a first router of the first network, a first border gateway protocol (BGP) message to request for routing information for a second node of a second network, the BGP message comprising an address-specific route target;
• receiving, by the first router from the second router of the second network, via a core network connecting the first network and the second network and implementing a seamless Multiprotocol Label Switching (MPLS) network with the first network and the second network, a second BGP message originated by the second node of the second network, the second BGP message indicating a transport class and specifying the address-specific route target, the transport class comprising one or more tunnels to the second node that share common characteristics;
• importing, by the first node in response to receiving the second BGP message comprising the address-specific route target, the routing information for the second node of the second network;
• and
• forwarding, by the first node and based on the routing information for the second node, network traffic to the second node via a tunnel associated with the transport class.

A first router connected to a first network and a core network, the first router comprising:

• one or more processors operably coupled to a memory, wherein the one or more processors are configured to:
• 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;
• receive, from a second router of a second network, via the core network connecting the first network and the second network and implementing a seamless Multiprotocol Label Switching (MPLS) network with the first network and the second network, a second BGP message originated by a second node of the second network, the second BGP message comprising the address-specific route target;
• and
• send, in response to receiving the second BGP message comprising the address-specific route target, the first BGP message to the second router for sending to the second node to cause the second node to import the routing information.