Spanning Tree Bridge Convergence Proposal Mechanism
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Solution Overview
Problem
Existing spanning tree protocols like RSTP and MST face delays in convergence due to synchronization operations and communication overhead, which slow down the propagation of topology changes across the network.
Innovation Solution
The proposed solution eliminates synchronization operations in the proposal/agreement mechanism by allowing a bridge to transmit convergence proposals downstream without syncing non-edge designated ports, ensuring that the blocking port unblocks only after receiving agreements from all leaves, thereby enabling end-to-end propagation of convergence information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization operations are performed in the proposal/agreement mechanism, then port state changes are ensured to be consistent across bridges, but convergence time is significantly increased due to waiting for multiple port state changes to complete
Solution Approach 1:
The patent segments the synchronization process by introducing version numbers to BPDUs. Instead of waiting for all port state changes to complete before propagating convergence information, the system divides the convergence process into multiple independent BPDU exchanges, each carrying version information that allows downstream bridges to proceed independently while maintaining consistency.
Solution Approach 2:
The patent performs preliminary actions by pre-incrementing the version number in the BPDU before transmission. This allows downstream bridges to immediately process the convergence information without waiting for upstream port state changes to complete, as the version number already reflects the intended state change. The actual port state change is decoupled from the propagation timing.
2Stability of the object's composition
If STP waits for port state changes to complete before propagating convergence information, then network consistency is maintained, but the propagation speed of topology changes is significantly reduced
Solution Approach 1:
The patent applies preliminary action by pre-incrementing the version number in the BPDU before the actual port state change occurs. This allows the convergence information to be propagated immediately at higher speed, while the actual state change follows afterward. The version number acts as a placeholder that maintains logical consistency without requiring physical synchronization.
Solution Approach 2:
The patent implements feedback through version number comparison. Downstream bridges compare the received BPDU version number with their local version number to determine whether to process the convergence information. This feedback mechanism ensures network consistency is maintained while allowing asynchronous propagation at high speed.
3Adaptability or versatility
If communication between different processes on distributed platforms is required for port state changes, then system modularity is improved, but additional processing time is lost due to inter-process communication overhead
Solution Approach 1:
The patent applies preliminary action by having the STP process pre-increment the version number and send the BPDU before the port state change is actually implemented by the forwarding process. This decoupling allows the STP process to proceed without waiting for inter-process communication completion, significantly reducing processing time while maintaining modularity.
Data Source
AI summary
In one embodiment, a bridge may receive a first convergence proposal on a root port from an upstream adjacent bridge of a computer network, and in response, may transmit a second convergence proposal downstream on each non-edge designated port of the bridge without syncing the non-edge designated ports. The bridge may then return a convergence agreement to the adjacent bridge in response to the non-edge designated ports having received a returned convergence agreement (or in response to having only edge designated ports). Also, according to embodiments, the adjacent bridge blocks a link to the root port until the convergence proposal(s) and agreement(s) travel end-to-end.