Router State Resynchronization for PCE Failure During Reoptimization
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Solution Overview
Problem
Stateful Path Computation Elements (PCEs) face challenges such as scalability issues, single point of failure, and complex state maintenance during network reoptimization, leading to unstable network states and increased signaling exchanges, especially when handling burst requests or PCE failures.
Innovation Solution
A router initiates tunnel reroutes, stores the original tunnel state, and detects PCE failure before optimization completion, reverting to the original state if failure occurs, using keep-alive protocols and timers to ensure network stability and prevent incomplete state transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stateful PCE is deployed to provide optimal path computation, then path computation optimality is improved, but system complexity and reliability are worsened due to state maintenance challenges and single point of failure
Solution Approach 1:
The patent segments the stateful PCE functionality by introducing a backup PCE that maintains a copy of the state database. This segmentation allows the primary PCE to fail without completely disrupting service, as the backup can take over. The segmentation of state maintenance responsibilities between primary and backup PCEs reduces the complexity burden on any single system component.
Solution Approach 2:
The patent implements beforehand cushioning by pre-configuring a backup PCE with a copy of the state database before any failure occurs. This cushioning mechanism protects against PCE failure during reoptimization processes, ensuring continuous operation. The backup PCE is ready to assume control immediately, preventing service disruption and reducing the impact of potential failures.
2Productivity
If PCE performs reoptimization to optimize network paths, then network performance is improved, but network stability is worsened due to incomplete state transitions and failure during optimization
Solution Approach 1:
The patent applies preliminary action by having the backup PCE pre-load a copy of the state database before the primary PCE begins reoptimization. This ensures that if failure occurs during optimization, the backup already has the necessary state information to maintain network stability. The preliminary preparation of backup state data prevents instability during transition.
Solution Approach 2:
The patent implements feedback mechanisms where the backup PCE monitors the primary PCE's operation status. If the primary PCE fails or becomes unresponsive during reoptimization, the backup receives feedback about this condition and can activate to take over. This feedback loop ensures that network stability is maintained by quickly responding to failure conditions and switching to backup operations.
3Measurement precision
If stateful PCE maintains tunnel states for optimal computation, then path computation accuracy is improved, but reliability is worsened due to single point of failure and lack of redundancy
Solution Approach 1:
The patent applies local quality by maintaining state information locally at both the primary and backup PCEs. Each PCE has its own copy of the state database, allowing independent operation. This local quality approach ensures that even if the primary PCE fails, the backup retains all necessary state information for accurate path computation, improving reliability without sacrificing accuracy.
Solution Approach 2:
The patent implements copying by creating a duplicate state database at the backup PCE. This copy contains the same tunnel state information as the primary PCE, enabling the backup to perform identical path computation functions. The copying of state data ensures that path computation accuracy is maintained while adding redundancy for improved reliability.
Data Source
AI summary
In one embodiment, a router initiates reroutes of one or more tunnels at the router as part of optimization of a plurality of tunnels in a computer network, and stores an original state of the one or more tunnels at the router prior to the optimization. By detecting whether path computation element (PCE) failure occurs prior to completion of the optimization, the router may revert to the original state of the one or more tunnels in response to PCE failure prior to completion of the optimization.