Edge Node Probe Packets for Accurate WAN Path Measurement

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Solution Overview

Problem

Current network performance measurement techniques in wide area networks are inaccurate and unreliable, particularly for service-level agreements, as they rely on two-way measurements that do not guarantee the use of specific forward and return paths, leading to false negatives in packet loss detection and inadequate latency, jitter, and loss assessment.

Innovation Solution

The method involves edge nodes identifying local and remote discriminators or forwarding identifiers to generate probe packets that ensure specific forward and return paths, allowing for accurate measurement of network performance by verifying that the probe packets follow the intended paths, using techniques such as differentiated service code points and multi-protocol label switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If two-way measurements are used to monitor network performance, then monitoring can be implemented with simple techniques, but measurement accuracy and reliability deteriorate due to inability to guarantee specific forward and return paths

Engineering Contradiction:

Improveease of implementationVSAvoidmeasurement accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The measurement process is segmented into separate forward and return path measurements using unidirectional probe packets. Each direction is measured independently with dedicated timestamping, allowing accurate assessment of each path's performance characteristics without contamination from the other direction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Timestamps are applied preliminarily at the source node before probe packets are transmitted through the network. This preliminary timestamping of probe packets enables accurate measurement of path performance by comparing the pre-applied timestamp with the reception timestamp, eliminating the need for complex two-way synchronization.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If traditional two-way measurement techniques are used, then implementation is straightforward, but reliability of packet loss detection deteriorates due to false negatives

Engineering Contradiction:

Improveease of operationVSAvoidreliability of packet loss detection

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The measurement approach is inverted from two-way symmetric measurement to unidirectional asymmetric measurement. Instead of measuring round-trip time and assuming symmetry, the system sends probe packets in one direction only and measures performance based on source timestamp and destination reception timestamp, eliminating false negatives caused by return path issues.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The probe packet serves as an intermediary carrier that transports the source timestamp through the network path. By embedding the timestamp within the probe packet itself, the system creates a self-contained measurement mechanism that reliably tracks packet journey without requiring complex coordination between source and destination nodes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of information

If multiple paths are monitored between edge nodes, then comprehensive network performance information can be obtained, but monitoring becomes difficult and unreliable using traditional techniques

Engineering Contradiction:

Improvenetwork performance informationVSAvoidmonitoring complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The measurement system applies local quality by allowing different path characteristics to be measured independently. Each probe packet traversal measures the specific performance of one path instance, enabling comprehensive monitoring of multiple paths with their unique performance characteristics without requiring complex coordinated measurement across all paths simultaneously.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system changes measurement parameters by using unidirectional probe packets with embedded source timestamps rather than traditional two-way synchronized measurements. This parameter change simplifies the monitoring mechanism while enabling accurate measurement of multiple paths, as each path can be measured independently using the same simplified unidirectional approach.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11671360B2Selecting forwarding paths and return paths in a networked environment

Publication Date: 2023.06.06 CISCO TECHNOLOGY INC

AI summary

Techniques for utilizing edge nodes disposed throughout a multi-site cloud computing network to generate a probe packet including indicators that guarantee the use of forward and return route paths to accurately measure the network performance of a route path between two endpoints in a wide area network (WAN). An edge node disposed in a site of the multi-site cloud computing network may store in virtual memory associated with the edge node, a mapping between route paths, usable to send data from the edge node to remote edge nodes in remote sites, and route indicators. A probe packet may include a data portion for measuring the network performance of a route path, a portion including local and remote discriminators, and/or an inner and an outer header.