Scheduled network layer programming within a multi-topology computer network

A path computation element comprising:

• a multi-topology traffic engineering database to store topology information for a base network layer of a multi-topology network, the multi-topology network comprising the base network layer having a plurality of network switches interconnected by base network layer three (L3) links in a base network topology and also comprising an overlay network layer having a plurality of overlay switches interconnected by overlay network links in an overlay network topology;
• a topology server interface configured to receive topology information for the base network layer;
• an overlay controller interface configured to receive topology information for the overlay network layer;
• a client interface configured to receive a path request that specifies two endpoints, a start time for path activation, and a requested bandwidth;
• a service path engine configured to compute, in response to receiving the path request and using the topology information for the base network layer and the topology information for the overlay network layer, a path to transport network traffic between the two endpoints,
• wherein the topology server interface and the overlay controller interface are further configured to, after the service path engine computes the path to transport network traffic between the two endpoints, receive additional topology information for one of the overlay network layer and the base network layer, and
• wherein the client interface is further configured to send, to the client in response to the service path engine determining the additional topology information indicates the path is not capable of transporting network traffic between the two endpoints at the requested bandwidth at the start time for path activation, a path rejection indicating the multi-topology network is unable to satisfy the path request.

A non-transitory computer-readable medium comprising instructions for causing one or more programmable processors to:

• receive, by a path computation element, topology information for a base network layer of a multi-topology network, the multi-topology network comprising the base network layer having a plurality of network switches interconnected by base network layer three (L3) links in a base network topology and also comprising an overlay network layer having a plurality of overlay switches interconnected by overlay network links in an overlay network topology;
• receive, by the path computation element from a client and via a client interface, a path request that specifies two endpoints, a start time for path activation, and a requested bandwidth;
• compute, by the path computation element in response to receiving the path request and using the topology information for the base network layer and the topology information for the overlay network layer, a path to transport network traffic between the two endpoints;
• by the path computation element and after computing the path to transport network traffic between the two endpoints, receive additional topology information for one of the overlay network layer and the base network layer;
• and
• send, by the path computation element to the client via the client interface and in response to determining the additional topology information indicates the path is not capable of transporting network traffic between the two endpoints at the requested bandwidth at the start time for path activation, a path rejection indicating the multi-topology network is unable to satisfy the path request.