Patent ID: 7944858
Filing Date: 2011-05-17
Classification: H04L

Abstract:
1. A method for protecting a network configuration set up by a spanning tree protocol, STP, by selecting one of a plurality of bridges of a computer network as a root bridge and by selecting one of a plurality of forwarding bridge ports of each of the plurality of bridges as a root port, wherein the selected one of the plurality of forwarding bridge ports is in a forwarding state, the method comprising the steps of: splitting the forwarding state of the bridge port to an active and a passive sub-state through an additional state machine unit added to each of the forwarding bridge ports; setting a sub-state of at least one forwarding bridge port of at least one of the bridges to an active sub-state as long as bidirectional payload traffic is conveyed through the forwarding bridge port; receiving an STP message, in particular a Bridge Protocol Data Unit, BPDLT, in one of the forwarding bridge ports being in the active sub-state, and protecting the network configuration by discarding the STP message and by sending an alarm message to a network management unit in case that the STP message indicates a change of the root bridge of the network configuration; wherein the change of the root bridge is indicated by a bridge port ID of the BPDU which is smaller than the bridge port ID of the root bridge of the network configuration.