Latency and Jitter Injection for Avionics Network Testing
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Solution Overview
Problem
Inserting faults such as latency and jitter into real-time computer networks, particularly in avionics networks, is challenging as existing methods struggle to precisely introduce these conditions only on selected packets without disrupting other network traffic, especially when simulating worst-case scenarios.
Innovation Solution
A network testing system with a computer and network interface that receives packet identifiers, computes and applies latency and jitter to specific packets based on real-time clock calculations, allowing for precise timing and minimal disruption to non-targeted packets, ensuring that only selected packets experience added latency and jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fault insertion is performed on all network packets, then comprehensive fault testing is achieved, but normal network traffic is disturbed
Solution Approach 1:
The patent applies local quality by selectively inserting faults only into specific packets identified by packet identifiers, rather than uniformly affecting all packets. The system distinguishes between target packets for fault injection and normal packets for uninterrupted transmission, thereby achieving comprehensive fault testing while minimizing disturbance to overall network traffic.
2Measurement precision
If latency and jitter are inserted in real-time only to selected packets, then precise fault testing is achieved, but network processing complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring packet identifiers and fault parameters before fault injection begins. The system prepares the selection criteria and latency/jitter values in advance, allowing real-time fault insertion into selected packets without requiring complex on-the-fly decision-making, thus achieving precise fault testing while managing processing complexity.
3Productivity
If 99% of network traffic is passed without disturbance, then normal network operations are maintained, but fault testing coverage is reduced
Solution Approach 1:
The patent applies partial action by injecting faults into a small subset of packets (e.g., 1% or less) identified by specific packet identifiers, while allowing the majority of traffic (99% or more) to pass undisturbed. This selective approach maintains high network throughput while still achieving meaningful fault testing coverage for critical packet types.
Data Source
AI summary
A method for adding latency and jitter to a number of selected packets transmitted between end systems within a network of end systems is described. The method includes receiving a packet identifier, the packet identifier indicating a selected packet to which latency and jitter is to be added, receiving a selected latency and jitter for the selected packet, receiving a packet, determining if the received packet is the selected packet, and forwarding the received packet to its destination if the received packet is not the selected packet. If the received packet is the selected packet, the method continues by reading a real time clock, computing a transmit time for the received packet based on the selected latency and jitter for the selected packet, and forwarding the received packet to its destination when the real time clock reaches the computed transmit time.