Patent ID: 7565435
Filing Date: 2009-07-21
Classification: H04L

Abstract:
1. A method for forwarding data frames between bridges within a computer network, the bridges including ports; said method comprising the steps of: creating and configuring a plurality of Multiple Spanning Tree Instances (MSTIs) whose active topology covers the topology of Virtual Local Area Networks (VLANs) being used within the computer network; creating VLAN member sets and associating each of said VLANs with an appropriate one of the MSTIs, each of said VLAN member sets indicating the ports in each of the bridges within one of the MSTIs to which data traffic destined to members of the associated VLAN is being forwarded; setting the Internal Port Path Cost (IPPC) of one of the ports of one of said bridges within the MSTI to a high IPPC when said port is not part of the VLAN member set; and setting the IPPC of one of the ports of one of said bridges within the MSTI to a lower IPPC when said port is part of the VLAN member set; said settings reestablish connectivity in one of the MSTIs experiencing a failure by activating links whose activation ensures that the connectivity within the VLAN mapped onto and associated with the MSTI is not lost; wherein said high IPPC is a value that is higher than any of the values used for the IPPCs of ports that are part of the VLAN member set; and said lower IPPC is a value that is based on a speed of the links that are connected to the corresponding ports that are part of the VLAN member set.