Link Redundancy Entity for Critical Device Availability
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Solution Overview
Problem
Industrial communication systems in critical applications like vehicle control and substation automation face challenges in maintaining high availability without relying on costly or failure-prone hardware such as dedicated external switches or embedded switch elements.
Innovation Solution
A critical device is equipped with two network controllers connected to two distinct switches, utilizing a Link Redundancy Entity (LRE) as a software module to manage communication, implementing a subset of the Rapid Spanning Tree Protocol (RSTP) and allowing the device to function as a Doubly Attached Node (DAN) in a ring-type network, reducing the need for special hardware and maintaining high availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full duplication of the physical network is implemented using PRP protocol, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements partial redundancy by allowing critical devices to be connected to only one switch in normal operation, rather than requiring full duplication to both switches. The redundancy is activated only when needed, reducing the complexity of permanent dual connections while maintaining availability.
Solution Approach 2:
The patent extracts the switching function from dedicated external switches and embeds it within the critical device itself. This eliminates the need for separate external switch hardware while maintaining the redundancy functionality, thereby reducing device complexity and cost.
2Reliability
If dedicated external switches or embedded switch elements are used, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the switching functionality with the critical device by implementing a virtual switch software module within the device. This combines multiple functions (critical device operations and switching) into a single integrated system, eliminating the need for separate external switch hardware and reducing overall device complexity.
Solution Approach 2:
The patent replaces physical switch hardware with a software-based virtual switch implementation. This substitution of mechanical/physical switching components with software-based logic maintains the redundancy functionality while reducing hardware complexity and inventory costs.
3Device complexity
If standard Ethernet controllers are used instead of special hardware, then device complexity is reduced, but reliability may be compromised
Solution Approach 1:
The patent makes standard Ethernet controllers multi-functional by implementing a virtual switch software module that enables these standard components to perform both their original networking function and the additional switching function for redundancy. This universality allows standard hardware to fulfill multiple roles, maintaining reliability without requiring specialized components.
Data Source
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AI summary
The present invention is concerned with increasing availability of critical devices (10) in redundant communication networks of a communication system. To ensure higher availability, the critical device is provided with a Link Redundancy Entity (LRE) (11) which can act as a switch when the critical device is part of the last communication link between two switches (2, 3) of the communication network. When the critical device is not a part of the last communication link, the LRE defines one port (13a) of the critical device to be the "root" port and the other port (13b) to be the "alternate" port. When the critical device works according to Parallel Redundancy Protocol (PRP), the LRE is adapted to send identical frames on two redundant communication links of the network and also to determine whether the received data frame is a singular frame or a first frame of a pair of frames.