Packet RTT Marking Synchronization Under Variable Traffic Rates
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Solution Overview
Problem
Existing RTT measurement techniques on live traffic in packet-switched networks suffer from unpredictable delays due to fluctuating packet rates, leading to unreliable measurements.
Innovation Solution
Nodes in the network apply marking values to packets based on detecting the opposite node's marking value changes, switching only if the time lapse between detections does not exceed predefined thresholds, ensuring reliable RTT measurements with a predictable maximum error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RTT measurement is performed on live traffic using spin bit reflection, then the measurement does not require mutual synchronization of local clocks, but the packet rate fluctuations cause unpredictable delays in spin bit reflection leading to unreliable measurements
Solution Approach 1:
The patent applies preliminary action by setting a maximum time threshold before the spin bit reflection can occur. Each endpoint waits for a packet to be transmitted within this predefined time threshold after detecting a spin bit change. This preliminary time constraint ensures that the reflection happens within a predictable window, preventing unbounded delays while maintaining the ability to perform RTT measurements on live traffic without requiring clock synchronization.
2Adaptability or versatility
If the spin bit reflection mechanism waits for the next packet to be transmitted, then it uses existing live traffic for measurement, but this causes unpredictable delay when packet rate becomes very low or zero
Solution Approach 1:
The patent sets a maximum time threshold as a preliminary constraint that bounds the waiting time for packet transmission. This ensures that even when packet rates are low, the reflection mechanism will not wait indefinitely, thus maintaining reliability and predictability of measurement timing while still allowing the use of live traffic for measurements.
Solution Approach 2:
The patent changes the parameter of time by introducing a maximum time threshold that limits the waiting period. This parameter change transforms the unbounded waiting time into a bounded interval, making the reflection delay predictable and the measurement reliable even under varying packet rates.
Data Source
AI summary
It is disclosed a method for performing a RTT measurement on a bidirectional packet flow transmitted between two nodes of a packet-switched communication network. Each node applies a respective marking value to its outgoing packets, and switches outgoing packet does not exceed a predefined time threshold. An intermediate measurement point may provide an RTT measurement as a time lapsing between two consecutive switching of the marking value in the packets transmitted in a certain direction.