Patent ID: 7801021

Claim:
A method comprising: constructing an outer encapsulated packet containing an inner encapsulated packet, the outer encapsulated packet including an outer delivery header that is used to deliver the outer encapsulated packet to a destination endpoint and an outer Generic Routing Encapsulation (GRE) header, and the inner encapsulated packet including an inner delivery header that is used to deliver the packet to a source endpoint and an inner GRE header; sending the outer encapsulated packet towards a destination endpoint; incrementing a counter to track a number of outstanding inner encapsulated packets, the number of outstanding inner encapsulating packets being a number of inner encapsulated packets that have been sent to but not received back from the destination endpoint; concluding the destination endpoint is unreachable if the number of outstanding inner encapsulated packets exceeds a predetermined threshold; and in response to the destination endpoint being concluded to be unreachable, setting a tunnel to a down state to prevent data packets from being forwarded by the tunnel.