Network Address Conversion for Active Standby Switching
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Solution Overview
Problem
Existing network systems with multiplexed control devices lack robustness due to reliance on a single optical switching means, making them vulnerable to failures that can disrupt the entire network operation.
Innovation Solution
A network system with multiple control devices, communication control devices, and monitoring devices that utilize an address conversion table to manage virtual and real network addresses, allowing seamless switching between active and standby systems without requiring additional special functions in network interface units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single optical switching means is used to switch between active and standby control devices, then the system structure is simple, but the robustness of the entire network system deteriorates because a failure of the optical switching means will prevent the system from continuing its operation
Solution Approach 1:
The patent divides the network system into multiple independent communication paths by assigning different communication addresses to standby control devices. Instead of relying on a single optical switching means, the system segments the communication flow through address-based routing, where monitoring devices and slave stations can communicate with any active control device using address conversion tables. This eliminates the single point of failure represented by the optical switching means.
Solution Approach 2:
The patent introduces address conversion tables as intermediaries between slave stations and control devices. These tables store mapping relationships between slave station addresses and control device addresses, enabling flexible routing without requiring physical switching means. The address conversion mechanism acts as a logical mediator that directs communication flow dynamically based on the active control device, eliminating the need for physical optical switches.
2Reliability
If the same communication address is set in both active and standby control devices to enable seamless switching, then communication continuity is improved, but address management complexity increases and requires additional switching infrastructure
Solution Approach 1:
The patent pre-configures address conversion tables in monitoring devices and slave stations with mapping relationships between slave station addresses and multiple control device addresses (both active and standby). This preliminary action ensures that when a control device switches from standby to active, the address conversion tables already contain the necessary routing information, enabling immediate communication continuity without requiring address reconfiguration or physical switching operations.
Solution Approach 2:
The patent changes the communication address parameter dynamically based on the active control device. Instead of using fixed addresses or requiring physical switching, the system modifies the address resolution process by updating address conversion tables to reflect the current active control device. This parameter change approach allows seamless switching while maintaining address management flexibility without requiring additional switching infrastructure.
3Reliability
If multiple communication control devices with different addresses are used to improve robustness, then system reliability is improved, but the complexity of address management and communication control increases
Solution Approach 1:
The patent implements a feedback mechanism where monitoring devices continuously monitor the status of control devices and automatically update address conversion tables in slave stations and other monitoring devices. When a control device fails or switches status, the monitoring device detects this change and propagates updated address mappings throughout the network. This feedback loop simplifies address management by automating the update process, eliminating the need for manual configuration despite having multiple communication control devices with different addresses.
Data Source
AI summary
A network system includes control devices, network interface units connected to the respective control devices, and operator interface stations each of which stores an address conversion table. Each of the network interface units includes a network-address setting unit to set a virtual identification information when the control device connected thereto is being set for an active system and to set proper identification information when the control device connected thereto is being set for a standby system, and includes an address-conversion-table update instruction unit to request the operator interface stations to update their respective address conversion tables on the basis of the identification information that has been set.