Reverse Loss Detection for Bandwidth Estimation in SD-WAN

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Solution Overview

Problem

Bandwidth measurement in SD-WAN architecture is challenging due to dynamic cross traffic and the inability to collect direct measurements from network devices in different administrative domains, leading to inaccurate or impossible bandwidth estimation.

Innovation Solution

The system employs end-to-end network path estimation using probe packets to measure available bandwidth by detecting packet losses and queuing delays, with methods like Probe Rate Model (PRM) and PathChirp, and can automatically reroute traffic and load balance based on the estimated bandwidth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct measurements are collected from network devices, then bandwidth measurement precision is improved, but device accessibility and administrative domain restrictions worsen measurement capability

Engineering Contradiction:

Improvebandwidth measurement precisionVSAvoidnetwork device accessibility

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent introduces probe packets as intermediaries to measure bandwidth indirectly. Instead of requiring direct access to network devices, the system sends probe packets through the network path and measures bandwidth based on probe packet transmission characteristics (delay, loss, rate), enabling measurement in administrative domains where direct device access is restricted

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces physical direct measurement mechanisms with signal-based indirect measurement. Rather than requiring direct connection to network devices for measurement, the system uses probe packet signals to infer bandwidth characteristics, substituting mechanical/access-based measurement with signal processing-based measurement

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If probe packets are sent at high rates to measure bandwidth, then measurement speed is improved, but packet loss increases affecting measurement accuracy

Engineering Contradiction:

Improvebandwidth measurement speedVSAvoidmeasurement accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent employs periodic probe packet transmission with varying rates. Probe packets are sent in periodic bursts or sequences at different rates, allowing the system to measure bandwidth characteristics across multiple transmission patterns. This periodic approach enables accurate measurement while managing packet loss through rate variation rather than continuous high-rate transmission

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent implements feedback mechanisms where the receiver sends acknowledgment information about probe packet reception status back to the sender. Based on this feedback (packet loss information, delay measurements), the system adjusts subsequent probe packet transmission rates, creating a closed-loop measurement process that maintains accuracy while optimizing measurement speed

Inventive Principle:

Principle #23Feedback

3Ease of operation

If token buckets are used to control traffic rates, then traffic management is improved, but reverse loss detection becomes difficult affecting bandwidth estimation

Engineering Contradiction:

Improvetraffic rate controlVSAvoidreverse loss detection difficulty

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The patent inverts the traditional loss detection approach. Instead of detecting loss in the forward direction (sender to receiver), it detects loss in the reverse direction by analyzing acknowledgment packets sent from receiver to sender. This inversion allows bandwidth estimation even when token buckets control the forward traffic rate, as the reverse path acknowledgments provide loss information without being constrained by the forward path rate limiting

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11888749B2Reverse loss detection for communication network bandwidth estimation with token buckets

Publication Date: 2024.01.30 HEWLETT PACKARD ENTERPRISE DEV LP

AI summary

Systems and methods are provided for measuring available bandwidth available in a black box network by determining a probing rate of packet transmissions between a sender and receiver. The optimal probing rate and bandwidth estimate may be determined. Additional actions may be performed, like automatically rerouting packets and/or load balancing network traffic after the probing rate is determined.