IPv6 Redundancy Handling Across Automation System Areas
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Solution Overview
Problem
Existing automation systems struggle to implement end-to-end redundancy across multiple system areas, as layer 2 redundancy protocols like PRP and HSR are limited to within a single system area, necessitating a solution for seamless redundancy across interconnected areas.
Innovation Solution
A transmitting redundancy handling device in the first system area and a receiving redundancy handling device in the second system area use IPv6 packets with a destination option header to handle redundancy by duplicating packets with sequence numbers and sending them through different communication paths, allowing the receiving device to discard duplicate packets based on sequence number matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layer 2 redundancy protocols (PRP/HSR) are used within a single system area, then reliability is improved, but adaptability deteriorates because they cannot work across multiple system areas
Solution Approach 1:
The patent segments the redundancy handling function into separate components: a transmitting redundancy handling device in the first system area and a receiving redundancy handling device in the second system area. This segmentation allows layer 2 redundancy to be effectively extended across multiple system areas by dividing the redundancy protocol into transmit and receive sides that operate independently in different areas while maintaining end-to-end redundancy functionality.
Solution Approach 2:
The patent introduces an intermediary mechanism using IPv6 packets with destination option headers containing sequence numbers. This intermediary approach allows the redundancy information to be carried across system area boundaries through standard IP networking, bridging the gap between layer 2 redundancy protocols and multi-area network architecture.
2Reliability
If duplicate packets are sent for redundancy, then reliability is improved, but processing overhead increases
Solution Approach 1:
The patent extracts the sequence number from the application data and places it in the IPv6 destination option header. This extraction allows the receiving device to quickly identify and discard duplicate packets by checking only the sequence number in the header, without needing to process the entire application data payload, thereby reducing processing overhead while maintaining reliability.
Solution Approach 2:
The transmitting device performs preliminary action by duplicating packets and assigning sequence numbers before transmission. The receiving device then uses these pre-assigned sequence numbers for rapid duplicate detection and discarding, eliminating the need for complex post-reception analysis and reducing overall processing overhead.
3Measurement precision
If sequence numbers are placed in destination option headers, then measurement precision is improved for duplicate detection, but device complexity increases
Solution Approach 1:
The patent uses the existing IPv6 destination option header structure for a new purpose - carrying sequence numbers for redundancy detection. This multi-functional use of the destination option header allows precise duplicate packet identification without requiring a completely new protocol structure, thereby limiting the increase in device complexity while achieving high measurement precision.
Data Source
AI summary
An automation system includes a first system area including a transmitting redundancy handling device and a second system area including a receiving redundancy handling device. Device obtains a first communication protocol packet with automation application data and a sequence number linked thereto, extracts the sequence number and places it in a destination option header of a first IPv6 packet, which also includes the first communication protocol packet, sends packet to the receiving redundancy handling device, obtains a second communication protocol packet having the same automation application data and sequence number, places the sequence number in a destination option header of a second IPV6 packet also including the second communication protocol packet, and sends packet to device. Device receives the packets, analyses the destination option headers, determines that the sequence number is the same in the packets and discards the first or the second IPv6 packet based on the determination.