Packet Delay Variation Tester for Network Jitter Accuracy
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Solution Overview
Problem
Standard approaches to generating packet delay variation in packet switched networks often result in packets being delayed for longer than intended, leading to reduced accuracy in network performance testing due to packets being sent back-to-back, which affects minimum latency and maximum jitter values.
Innovation Solution
A packet switched network in-line tester that dynamically applies packet delay variations by detecting whether a test profile delay would result in a packet being delayed after preceding packets, allowing only accurate delays to be applied, ensuring that packets are not sent back-to-back and maintaining minimum latency and maximum jitter accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If packets are delayed according to test profile with high packet rate, then packet delay variation is generated, but packets are delayed longer than intended and sent back-to-back
Solution Approach 1:
The system continuously monitors the actual departure time of each packet and compares it with the expected departure time from the test profile. This feedback mechanism detects when packets are delayed longer than intended and triggers corrective action by adjusting subsequent packet delays to compensate for the accumulated timing error, thereby maintaining accurate jitter test results even under high packet rates
Solution Approach 2:
The packet delay mechanism transitions from a static, predetermined delay schedule to a dynamic, adaptive system. The delay applied to each packet is adjusted in real-time based on the actual network conditions and the departure times of previous packets. This dynamic adjustment ensures that packets are delayed by the correct amount according to the test profile, preventing back-to-back packet transmission and maintaining measurement accuracy
2Quantity of substance
If packets are delayed using standard approach, then packet delay variation is applied, but minimum latency is not achieved and maximum jitter is reduced
Solution Approach 1:
The system pre-calculates the optimal delay for each packet based on the test profile and the inter-packet gap, before the packet actually arrives at the output sequencer. This preliminary determination of delay values ensures that when packets are delayed, they achieve the minimum latency required by the test profile and the maximum jitter variation is maintained, rather than being constrained by previous packet delays
Data Source
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AI summary
A packet switched network tester for testing a network using a packet delay variation test profile that has a plurality of different delays for applying to timestamps of packets received at the tester, the tester being configured to: detect a packet; determine whether a test profile delay when applied to the packet would result in a packet delayed to a time after any preceding packet; if not, repeat the steps of detecting and determining with subsequent packets; if yes, apply the delay to the timestamp of the packet and identify the next test profile delay; and repeat for the next test profile delay the steps of detecting and determining.