One-Way Delay Measurement in Packet Networks with Directional 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 a critical round-trip time, making it difficult to identify congestion sources.
Innovation Solution
A method where bidirectional packet flows carry marking fields set to specific values, allowing a single measurement point to determine one-way delay by detecting marked packets at predefined times, enabling end-to-end and upstream one-way delay measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If RTT measurement is performed using spin bit technique, then measurement can be performed with a single measurement point, but the contribution of each direction (upstream or downstream) to the overall RTT cannot be determined
Solution Approach 1:
The bidirectional packet flow is segmented into two independent unidirectional flows (upstream and downstream). Each flow is marked independently with marking fields, allowing the measurement point to separately measure and identify the delay contribution of each direction while still using a single measurement point.
Solution Approach 2:
Different marking values are assigned to packets based on their direction (upstream or downstream). The measurement point can locally distinguish and measure each direction's delay by detecting the specific marking values, thereby obtaining directional information without adding multiple measurement points.
2Productivity
If one-way delay measurement is performed on live traffic packets, then measurement does not interrupt normal traffic, but accurate measurement of directional delays requires sophisticated marking techniques
Solution Approach 1:
The marking fields are integrated into the existing packet headers, allowing the same packet structure to serve both normal traffic transmission and measurement purposes. The marking mechanism works on live traffic without requiring separate measurement traffic, achieving multi-functionality.
Solution Approach 2:
Marking fields with specific values are added or modified in the packet headers to enable directional identification. These parameter changes allow the measurement point to distinguish upstream from downstream packets while the packets continue to carry normal traffic data, maintaining continuous transmission.
3Measurement precision
If multiple measurement points are deployed to measure one-way delays in both directions, then accurate directional measurement is achieved, but network complexity and measurement overhead increase
Solution Approach 1:
The marking fields act as intermediaries that carry directional information through the network. Instead of requiring multiple measurement points to directly observe each direction, the marking fields mediate the information transfer, allowing a single measurement point to infer directional delays by detecting the marking values in packets.
Solution Approach 2:
The solution adds a new dimension of information (marking fields with directional values) to the existing packet structure. This dimensional addition enables a single measurement point to access directional delay information that would otherwise require multiple spatial measurement points, effectively transforming a spatial problem into an information-dimensional problem.
Data Source
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AI summary
It is disclosed a method for performing a one-way delay measurement on a bidirectional packet flow carrying live traffic exchanged between two nodes of a packet-switched communication network. At predefined times, each node transmits to the other node a respective marked packet of the bidirectional packet flow. Each node then transmits unmarked packets of the bidirectional packet flow, until it receives the marked packet transmitted by the other node. In response thereto, each node transmits to the other node another marked packet of the bidirectional packet flow. A measurement point may be placed on the path of the bidirectional packet flow, for detecting the marked packets transmitted in either direction, and for providing a one-way delay measurement based on their detection times.