Patent ID: 7889655

Claim:
A method, comprising: receiving a control plane message at a first edge node of a first collection of network nodes that are configured to share different routing information within the first collection of network nodes than is shared outside the first collection of network nodes, which first edge node is connected to a different second edge node of a different second collection of network nodes that are configured to share different routing information within the second collection of network nodes than is shared outside the second collection of network nodes, wherein the control plane message includes data that indicates a particular network address of a particular node that is reachable from the first edge node; determining distinguisher data that indicates information that can be used to determine if a node in the first collection of network nodes can reach the first edge node without leaving the first collection of network nodes; and sending an advertising control message from the first edge node to the second edge node that includes route data that indicates the particular network address, and the distinguisher data, whereby a testing edge node in the first collection of network nodes can determine based on the distinguisher data whether there is a loop comprising both a first path between the testing edge node and the first edge node within the first collection of network nodes and also a second path between the testing edge node and the first edge node, wherein the second path includes nodes outside the first collection of network nodes, wherein if the loop is detected then the advertising control message is rejected and the route data is not incorporated into a routing table, wherein the distinguisher data is provided in fields of the control plane message, the advertising control message, and the routing table, and wherein the routing table includes entries for specific protocol distinguisher data for separate level two and level three routing determinations such that internal routes within a defined network boundary can be identified.