VLAN Tag-Based Detour Routing for RPR Cascade Network Fault Tolerance
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Solution Overview
Problem
In RPR (Resilient Packet Ring) cascade topology networks, failures lead to network partitioning, and existing detour path solutions either exceed the 50 ms recovery time or reduce frame transfer capacity due to increased frame sizes when encapsulating RPR frames in Ethernet frames.
Innovation Solution
The implementation of a communication device and method that uses opposing node information to form a pseudo-ring topology, allowing swift switching to a detour network upon failure, while maintaining frame transfer capacity by storing destination node information in VLAN tags and minimizing header size changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RPR frames are encapsulated in Ethernet frames for detour transmission, then network connectivity is restored after failure, but frame transfer capacity is reduced due to increased frame size
Solution Approach 1:
The patent extracts only the essential destination node information from the RPR frame header and stores it in a VLAN tag within the Ethernet frame. This selective extraction minimizes the additional header overhead while maintaining the ability to route frames through the detour path, thereby preserving frame transfer capacity while restoring network connectivity.
Solution Approach 2:
The patent changes the parameter representation of destination node information by encoding it in a compressed format within the VLAN tag field of the Ethernet frame. This parameter transformation allows the same routing information to be carried with minimal additional bytes, preventing the reduction of frame transfer capacity that would otherwise occur due to encapsulation overhead.
2Reliability
If detour path is established for fault tolerance, then network partitioning is prevented, but recovery time exceeds 50 ms requirement
Solution Approach 1:
The patent performs preliminary actions by pre-establishing the detour path and pre-configuring the opposing node information in VLAN tags before any failure occurs. When a failure is detected, the system can immediately switch to using the pre-configured detour path without requiring time-consuming path calculation or configuration, thereby achieving recovery within the 50 ms requirement while preventing network partitioning.
3Quantity of substance
If opposing node information is stored in VLAN tags, then frame transfer capacity is maintained, but device complexity increases
Solution Approach 1:
The patent makes the VLAN tag field serve multiple functions: it carries both the traditional VLAN identification information and the opposing node information needed for detour routing. This multi-functionality approach allows the same data structure to support both standard Ethernet VLAN operations and the enhanced fault tolerance capability, thereby maintaining frame transfer capacity without proportionally increasing device complexity.
Data Source
AI summary
A communication device is connected to an end of a first network of a cascade topology, and also to a second network. This communication device transmits a first list including information of communication devices, in the first network, that are destinations of transmission of frames through the first network, to an opposing communication device, in the second network, located at another end of the first network, and receives, from the opposing communication device, a second list including information of communication devices, in the first network, that are destinations of transmission of frames from the opposing communication device through the first network. The communication device determines in which of the first list and the second list a destination of a frame is included, and when the destination of the frame is included in the second list, transmits the frame to the second network.