Alternate Spanning Tree Protocol for Link Failure Recovery
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Solution Overview
Problem
Current Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP) technologies experience substantial time delays in reconvergence after a link failure, particularly in larger ring topologies, leading to prolonged network downtime and performance impact.
Innovation Solution
The alternate spanning tree protocol identifies rings within a network and pre-computes alternate port information to quickly restore connectivity upon link failure by sending pre-computed messages and unblocking alternate ports, allowing for faster reconvergence without extensive computational overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Spanning Tree Protocol (STP) or Rapid Spanning Tree Protocol (RSTP) is used for link failure recovery, then network topology management is maintained, but substantial time delays occur in reconvergence after link failure
Solution Approach 1:
The patent pre-computes and stores alternate spanning tree information during normal operation, including identifying alternate ports and calculating alternate paths before failures occur. When a link failure happens, the system immediately retrieves pre-computed alternate paths and activates them without performing complex real-time calculations, thus dramatically reducing reconvergence time while maintaining reliable failure recovery
2Reliability
If redundant links are added to provide alternative paths, then network reliability improves, but loops are created causing broadcast storms
Solution Approach 1:
The system pre-identifies and marks alternate ports during normal operation that would create loops if activated. These alternate ports are kept blocked under normal conditions but are pre-configured with their alternate path information. When a failure occurs, the system can safely activate these pre-validated alternate ports without creating broadcast storms, as their loop-creating nature has been pre-accounted for in the spanning tree calculation
Solution Approach 2:
The patent introduces an intermediate alternate spanning tree calculation layer between the physical redundant links and the active network topology. This intermediate layer identifies which redundant links can be safely activated as alternates without creating loops, acting as a mediator that allows redundancy while preventing broadcast storms by carefully selecting which alternate ports to block and which to potentially activate
3Reliability
If complex alternate path calculations are performed in real-time during link failure, then accurate recovery paths are found, but computational overhead increases processing time
Solution Approach 1:
The patent performs the complex alternate spanning tree calculations in advance during normal operation, building and storing a database of alternate paths and alternate port identifiers. During link failure, the system simply retrieves the pre-computed alternate path information from memory and activates the corresponding alternate ports, avoiding any complex real-time calculations and achieving near-instantaneous recovery with high path accuracy
Data Source
AI summary
Methods and apparatus that form the basis of an alternate spanning tree protocol that may be used, for example, to identify rings within a properly converged network configured by the spanning tree protocol (STP) or rapid spanning tree protocol (RSTP) are provided. With the knowledge of these rings, the alternate spanning tree has predetermined an alternate port that can restore connectivity without further computation in case of a link failure, thereby providing for extremely fast reconvergence.