TRILL Bridge Link Failure Handling via Pre-computed ECMP Paths
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Solution Overview
Problem
Current network protocols, such as TRILL, face inefficiencies in handling link failures, particularly in TRILL campus topologies, as they often require costly and resource-intensive SPF computations for every link change, leading to network disruptions and high CPU usage.
Innovation Solution
The method involves maintaining a communication path table that identifies and updates active paths upon link failures, allowing for rapid re-routing without immediate SPF computations, thereby minimizing network disruptions and CPU load by recording alternative ECMP paths for later use during routine maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SPF computations are performed for every link failure in TRILL campus topology, then network routing accuracy is maintained, but CPU usage increases and network disruptions occur
Solution Approach 1:
The patent pre-calculates and stores multiple equal-cost paths (ECMP) and alternative paths before link failures occur. When a link failure is detected, the system immediately switches to a pre-computed alternative path without performing SPF computation, thus maintaining routing accuracy while avoiding CPU-intensive operations during failures.
Solution Approach 2:
The system dynamically maintains multiple forwarding tables with different path options (ECMP paths and alternative paths). Based on real-time link status, the system dynamically selects the appropriate forwarding table without re-computing routes, enabling fast adaptation to link failures while reducing computational overhead.
2Reliability
If SPF computations are performed for every link failure, then optimal routing paths are ensured, but network disruption time increases
Solution Approach 1:
Alternative paths are pre-computed and stored in forwarding tables before link failures occur. When a failure is detected, the system immediately activates a pre-prepared alternative path, eliminating the time required for SPF computation during the failure event and thus reducing network disruption time while maintaining routing optimality.
Solution Approach 2:
The system skips the time-consuming SPF computation step by using pre-computed alternative paths. When link failures occur, the system rushes through the failover process by directly switching to stored alternative forwarding tables, significantly reducing the time required to restore optimal routing.
3Productivity
If multiple equal cost paths are used for ECMP routing, then network resource utilization improves, but complexity in handling link failures increases
Solution Approach 1:
The patent segments the routing information into multiple independent forwarding tables, each containing ECMP paths and alternative paths for specific failure scenarios. This segmentation allows the system to maintain high network resource utilization through ECMP while simplifying failure handling by selecting from pre-segmented alternative paths without complex real-time computations.
Solution Approach 2:
The system changes the state of forwarding tables based on link status parameters. When link failures occur, the system transitions from using ECMP forwarding tables to alternative path forwarding tables by changing the active forwarding table parameter, thereby maintaining resource utilization while simplifying failure handling through parameter-based table selection.
Data Source
AI summary
A method for maintaining a bridging network communication path table is presented and includes determining a failed communication link between a first bridge computer and a second bridge computer in the bridging network; identifying, in the communication path table, a first path that includes the failed communication link; and indicating that the first path is not active.