Patent ID: 8315157

Claim:
A method comprising: receiving and processing, using a processor at a first network element included in a network having an existing network topology, alternate network topology calculating information sent from a second network element that is to be removed from or inserted into the network; determining, prior to removal or insertion of the second network element and using the processor at the first network element, a standby network topology from the alternate network topology calculating information received and processed at the first network element, where the standby network topology, having the second network element removed or inserted, is to be enforced when the second network element is removed from or inserted into the network and where the alternate network topology calculating information comprises a high metric indicating that the second network element is not reachable by existing routes from the other network elements, where the network has an existing topology including the first network element and a tag signaling the first network element to start calculating alternate routes defining a standby network topology not including the second network element but to continue forwarding packets on the existing network topology while calculating the standby topology; continuing to enforce the existing network topology and to send messages on the existing network topology, using the processor at the first network element, while the standby network topology is being determined so that the standby network topology is determined in a parallel and non-disruptive manner prior to removal or insertion of the second network element; and enforcing the standby network topology and sending messages on the standby network topology, using the processor at the first network element, after receipt of a notification from the second network element that the second network element is being removed from or inserted into the network.