VLT Connection Failure Handling via ICL Redirection
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Solution Overview
Problem
Current network switching products face challenges in handling connection failures efficiently, particularly in virtual link trunk (VLT) configurations, which can lead to significant network traffic disruptions and delays in updating forwarding data structures.
Innovation Solution
The method involves detecting connection failures and redirecting packets using a failover Link Aggregation Group (LAG) with an inter-chassis link (ICL), setting a redirection status bit to facilitate rapid forwarding around failure points, and updating forwarding data structures to utilize the ICL, thereby minimizing traffic disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional forwarding data structure updates are used in VLT configurations, then network connection failures can be handled with redundant paths, but significant network traffic disruptions and delays occur
Solution Approach 1:
The patent pre-configures alternate next-hop addresses in forwarding data structures for each possible failure scenario. When a connection failure is detected, the switching unit can immediately switch to the pre-configured alternate path without waiting for forwarding table updates, thus eliminating traffic disruption delays while maintaining reliability through redundant paths.
2Reliability
If VLT configurations are implemented to provide redundant paths, then network reliability improves, but forwarding function complexity increases
Solution Approach 1:
The patent segments the forwarding decision process into two parts: the main forwarding table for normal operation and separate failure scenario configurations for each possible link failure. This segmentation allows the system to maintain simple forwarding operations under normal conditions while having pre-prepared alternate paths ready for failure scenarios, thus improving reliability without significantly increasing operational complexity.
3Loss of time
If rapid packet redirection is implemented using redirection status bits, then network traffic loss is reduced, but packet processing complexity increases
Solution Approach 1:
The patent uses a redirection status bit in the packet header to mark packets that need rapid redirection. This local quality marker allows the switching unit to quickly identify and handle only the affected packets with special processing, while leaving normal packets to follow the standard forwarding path. This minimizes the increase in packet processing complexity by affecting only a small subset of packets rather than all packets.
Data Source
AI summary
A system and method for rapid virtual link trunk connection failure handling includes receiving a packet at a first network switching unit where the packet is to be forwarded to a second network switching unit, detecting a failure in a network connection between the first network switching unit and the second network switching unit and associated with a first LAG of the first network switching unit, determining a second LAG associated with an inter-chassis link (ICL) as a failover LAG for the first LAG, redirecting the packet to the second LAG, altering the packet to set a redirection status bit to a logic value, and forwarding the altered packet using the ICL.