Abstract: A network may include a core region having routers and peripheral regions coupled to the core regions. Switches controlled by a controller may be interposed between the routers. The controller may maintain network topology information of the network. A path computation module may identify forwarding paths between the network routers based on the network topology information and other information such as network traffic history, current network traffic conditions, future network traffic forecasts, or other desired network information. The controller may control the switches to implement the identified forwarding paths. The controller may detect network topology changes and update forwarding paths based on the detected network topology changes. The controller may determine weights of path segments of the network topology. A routing module may provide the path segment weights to the routers using a network protocol.

Abstract: A network controlled by a controller may include end hosts that are coupled to the switches. The network may be coupled to gateways that interface between the network and an external network. The network may include subnetworks formed from respective portions of the end hosts of the network. The controller may create virtual gateways that interface between each of the subnetworks and the network by providing the end hosts of each subnetwork with virtual gateway Ethernet addresses. The controller may receive a network packet having a virtual gateway Ethernet address from an end host of a given subnetwork. The network packet may be destined for an end host of an external network or subnetwork. The controller may forward the network packet to the destination end host by redirecting the network packet through a selected gateway or by controlling the switches to perform gateway functions.

Abstract: A network controlled by a controller may include end hosts that are coupled to the switches. The network may be coupled to gateways that interface between the network and an external network. The network may include subnetworks formed from respective portions of the end hosts of the network. The controller may create virtual gateways that interface between each of the subnetworks and the network by providing the end hosts of each subnetwork with virtual gateway Ethernet addresses. The controller may receive a network packet having a virtual gateway Ethernet address from an end host of a given subnetwork. The network packet may be destined for an end host of an external network or subnetwork. The controller may forward the network packet to the destination end host by redirecting the network packet through a selected gateway or by controlling the switches to perform gateway functions.