One-Way Delay Measurement with Bidirectional Packet Marking
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Solution Overview
Problem
Existing methods for one-way delay measurements in packet-switched communication networks do not provide insights into which direction (upstream or downstream) contributes to the overall round-trip time (RTT) if the RTT exceeds a critical value, making it difficult to identify congestion points.
Innovation Solution
A method where bidirectional packet flows between nodes include marking fields that switch between predefined marking values to enable a single measurement point to calculate one-way delay measurements by detecting the duration of measurement packet blocks, allowing for end-to-end and upstream one-way delay measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If RTT measurement is used with a single measurement point, then device complexity is reduced, but measurement precision is insufficient to identify directional congestion contributions
Solution Approach 1:
The patent segments the bidirectional packet flow into two separate directional flows (upstream and downstream) by using different marking values (e.g., 0 and 1) to identify packets traveling in opposite directions. This allows a single measurement point to separately measure and analyze delay characteristics for each direction independently, resolving the contradiction between using one measurement point and achieving directional measurement precision.
2Measurement precision
If alternate marking technique is used with periodic switching, then one-way delay measurement becomes possible, but device complexity increases due to marking management
Solution Approach 1:
The measurement packets carry their own marking values that enable automatic identification of transmission direction and block boundaries. The marking values are self-contained in the packet headers, allowing receiving nodes to automatically process and measure delays without external coordination or complex control mechanisms, thus reducing device complexity while maintaining measurement precision.
3Productivity
If measurement packet blocks are transmitted continuously, then productivity is improved, but loss of time occurs due to congestion during measurement periods
Solution Approach 1:
The patent changes the marking value parameter periodically to switch between different measurement packet blocks (e.g., from marking value 0 to marking value 1). This parameter switching allows the system to interleave measurement packets with regular traffic, enabling continuous operation while reducing the impact of congestion on any single measurement block, thus balancing productivity and time loss.
Data Source
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AI summary
It is disclosed a method for providing one-way delay measurements on a bidirectional packet flow exchanged between two nodes of a packet-switched network. Each packet of the bidirectional packet flow comprises a marking field. At predefined times, the two nodes start transmission of respective measurement packet blocks made of packets with marking field set equal to a measurement value. Each node continues transmission of the respective measurement packet block, until it starts receiving the measurement packet block transmitted by the other node. In response thereto, each node ends transmission of the respective measurement packet block. A measurement point placed on the path of the bidirectional packet flow detects the measurement packet blocks and provides one-way delay measurements based on their time properties. For example, the end-to-end one-way delay in a given direction may be measured as the duration of the measurement packet block transmitted in the opposite direction.