Network Management Clock Skew Correction
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Solution Overview
Problem
Network management systems face inaccuracies in calculating reportable rates due to clock discrepancies between the network management server and polled devices, particularly evident in peak utilization reports and exacerbated by increased network load and resource constraints.
Innovation Solution
A method is implemented to synchronize clocks by computing and applying corrections to the normalization time using both the network management server's and polled device's clock times, with thresholds to determine when corrections are necessary and discarding data if discrepancies are too large, ensuring accurate timestamping and data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the network management system uses deltaTime to normalize counter differences, then the system can calculate rates, but the accuracy of rate calculations deteriorates when poll responses suffer inordinate delays or when network load increases
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors the actual poll response times and compares them against expected timing. When deviations are detected (indicating clock skew), the system automatically adjusts the normalization time by applying corrections derived from the observed timing discrepancies. This closed-loop feedback ensures that rate calculations remain accurate even when poll responses experience delays or when network conditions vary.
Solution Approach 2:
The system dynamically changes the normalization time parameter based on observed clock skew. Instead of using a fixed deltaTime, the system computes corrections to the normalization time by comparing timestamps from multiple poll responses and adjusting the parameter accordingly. This parameter adaptation allows the system to maintain measurement precision despite variations in network conditions and clock synchronization issues.
2Measurement precision
If the system applies corrections to synchronization time based on clock comparisons, then clock accuracy improves, but the complexity of the polling system increases
Solution Approach 1:
The system applies partial corrections to the normalization time rather than completely replacing the original deltaTime. By applying only the necessary correction amount (the skew detected between clocks) rather than a full re-synchronization, the system improves clock accuracy while minimizing the added complexity. The correction is applied selectively based on the magnitude of detected skew, avoiding unnecessary computational overhead.
3Measurement precision
If the system computes corrections using both local and remote device clock times, then timestamp accuracy improves, but the processing time and computational resources increase
Solution Approach 1:
The system performs preliminary computations during the polling process itself, calculating clock skew corrections as part of the normal poll response handling. By integrating the skew detection and correction computation into the existing polling workflow rather than adding separate processing steps, the system achieves accurate timestamps without significantly increasing overall processing time. The corrections are computed incrementally as poll responses are received.
Data Source
AI summary
A method of processing data received at a local system in response to polling a remote device, wherein the local system includes a local clock, the method involving: sending a first poll to the remote device; receiving a response from the remote device to the first poll, the response to the first poll containing data and a time stamp indicating when the remote device responded to the first poll; for the data received in response to the first poll, computing a first time by using both a time that was derived from the local clock for a previous poll of the remote device and also the time stamp contained in the response to the first poll; comparing the computed first time to information that the local system stored in connection with the first poll, wherein the information that the local system stored in connection with the first poll was derived from the local clock; and determining how to process the data received in response to the first poll based on comparing the computed first time to the information that the local system stored in connection with the first poll.