Patent ID: 7596101

Claim:
A frame forwarding system comprising a first bridge network connected to a second bridge network outside the frame forwarding system, the first bridge network comprising: a plurality of frame forwarding devices each comprising a logical bridge port connected to the second bridge network and an inter-node connection port, the logical bridge port being managed according to logical port state information; a plurality of links that interconnect the plurality of frame forwarding devices through the inter-node connection ports that are set to a forwarding state; system state sharing means, disposed in each frame forwarding device, for producing and sending a control message to other frame forwarding devices on the first bridge network in response to a spanning tree protocol (STP) bridge protocol data unit (BPDU) received from the second bridge network, the control message containing, in addition to the received STP BPDU, a logical bridge port number indicating the logical bridge port through which the frame has been received; frame forwarding means, disposed in each frame forwarding device, for forwarding data frames received from the second bridge network according to the logical port state information corresponding to the logical bridge port through which the data frames have been received; and system state updating means, disposed in each frame forwarding device, for updating the logical port state information according to the logical bridge port number and STP BPDU received as part of the control message from other frame forwarding devices on the first bridge network, while maintaining the forwarding state of the inter-node connection ports.