TSN Reset Mechanism Duplicate Delivery Prevention
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Solution Overview
Problem
The reset method for the Sequence recovery function in IEEE 802.1CB may cause temporary duplicate delivery in Time Sensitive Networking (TSN) networks, which is not acceptable as it violates the resource constraints and Quality of Service (QoS) requirements.
Innovation Solution
Implementing a reset-guard period or modifying the reset procedure based on the root-cause of the reset to ensure that no duplicate delivery occurs due to the reset of the sequence generation function. This involves discarding received packets during the reset-guard period or handling resets differently based on their cause.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reset method for the Sequence recovery function is implemented as defined in IEEE 802.1CB, then the elimination function can recover from timeout scenarios and get back in step with the Sequence generation function, but temporary duplicate delivery occurs which violates resource constraints and QoS requirements
Solution Approach 1:
The patent applies preliminary action by resetting the elimination function's sequence number to a value lower than the current sequence number before actual reset occurs. This anticipatory reset ensures that when the timeout recovery happens, packets are discarded during the transition period, preventing duplicates from being delivered while maintaining the ability to recover from timeout scenarios
Solution Approach 2:
The patent implements preliminary anti-action by proactively discarding packets during the reset transition period. By setting the reset sequence number lower than the current sequence number and discarding packets with sequence numbers between these values, the system pre-empts the potential duplicate delivery problem before it can occur, while still allowing recovery from timeout scenarios
2Object-generated harmful factors
If packets are discarded during reset transition period, then duplicate delivery is prevented, but resource utilization efficiency decreases due to unnecessary packet drops
Solution Approach 1:
The patent changes the sequence number parameter dynamically during reset operations. By setting the reset sequence number to a specific value lower than the current sequence number, and using this parameter to control packet acceptance/discarding decisions, the system achieves precise control over when packets are dropped, minimizing unnecessary losses while preventing duplicates
Solution Approach 2:
The patent replaces the traditional mechanical reset approach (simply clearing the sequence history) with a more sophisticated sequence number comparison mechanism. Instead of blindly accepting or discarding packets during reset, the system uses sequence number comparisons to make intelligent decisions, reducing unnecessary packet losses while maintaining duplicate prevention
Data Source
AI summary
Systems and methods for avoiding duplicate delivery in the reset mechanism of seamless redundancy, e.g., of a Time Sensitive Networking (TSN) network or Deterministic Networking (DetNet) network, are disclosed herein. In one embodiment, a method performed by a receiving node comprises receiving packets from multiple streams from a transmitting node via a network, each being a replication of a particular packet stream and each packet comprising a sequence indication. The method further comprises performing an elimination procedure, wherein performing the elimination procedure comprises resetting one or more parameters utilized by the elimination procedure responsive to an occurrence of an event while receiving the packets and, responsive thereto, discarding all of the received packets processed by the elimination procedure from a time at which the elimination procedure was reset until an end of a defined period of time.