Method and apparatus for rapidly reconfiguring computer networks

In an intermediate network device having a plurality of ports for forwarding messages between one or more network entities, the device executing a spanning tree algorithm to elect a root, and configurable to include two or more trunk ports for providing network connectivity to the root, a method for rapidly reconfiguring the intermediate network device, the method comprising the steps of:

• electing a single one of the two or more trunk ports to be placed in a forwarding spanning tree port state to allow messages to be forwarded to and from the elected trunk port;
• placing all other trunk ports providing connectivity to the root in a blocking spanning tree port state to prevent messages from being forwarded to or from these trunk ports;
• detecting a failure at the elected trunk port that is in the forwarding spanning tree port state;
• and
• in response to the step of detecting, transitioning a selected one of the other trunk ports from the blocking spanning tree port state directly to the forwarding spanning tree port state without transitioning the selected trunk port through either a listening or a learning spanning tree port state, allowing messages to be forwarded to and from the selected trunk port.

An intermediate network device for forwarding messages among a plurality of network entities of a computer network, the intermediate network device comprising:

• a plurality of ports;
• a spanning tree state machine engine operatively coupled to the plurality of ports and configured to execute a spanning tree algorithm so as to elect a root and to transition the ports among a plurality of spanning tree port states including blocking, listening, learning and forwarding;
• and
• means for detecting a failure at the plurality of ports, wherein the spanning tree state machine is arranged to place a first port that provides connectivity to the root in the forwarding spanning tree port state, and to place all other ports providing connectivity to the root in the blocking spanning tree port state, and further
• wherein in response to a failure at the first port, the spanning tree state machine engine transitions a selected one of the other ports providing connectivity to the root directly to the forwarding spanning tree state without transitioning the selected port through either the listening or learning spanning tree port states.

In an intermediate network device having a plurality of ports for forwarding messages between one or more network entities, the device executing a spanning tree algorithm to elect a root and to transition the ports among a plurality of spanning tree port states including blocking, listening, learning and forwarding in response to processing a plurality of spanning tree parameters, the intermediate network device further including two or more trunk ports that provide network connectivity to the root, a method for rapidly reconfiguring the ports of the device, the method comprising the steps of:

• manipulating one or more of the spanning tree parameters at the intermediate network device so that (1) only one of the two or more trunk ports transitions to the forwarding spanning tree port state and (2) all other trunk ports transition to the blocking spanning tree port state;
• detecting a failure at the one trunk port that is in the forwarding spanning tree port state;
• and
• in response to the step of detecting, transitioning a selected one of the other trunk ports from the blocking spanning tree port state directly to the forwarding spanning tree port state without transitioning the selected trunk port through either a listening or a learning spanning tree port state, allowing messages to be forwarded to and from the selected trunk port.