WAN Egress Shaper Rate Adaptation Using Sequence-Based Loss Measurement
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Solution Overview
Problem
Existing methods for detecting active bandwidth capacity in wide area networks (WANs) for adaptive Quality of Service (QoS) involve sending short bursts of bi-directional traffic, which impacts user traffic, and traditional algorithms for measuring WAN link loss are inaccurate due to varying clock shifts and only consider link loss, leading to inefficient bandwidth utilization.
Innovation Solution
A system and method for adjusting a WAN egress shaper rate based on accurately measured shaper loss and WAN link loss, using sequence counters to determine sender and receiver sequence numbers, allowing for synchronized monitoring cycles to calculate drop values and adjust the shaper rate without additional probing, thus optimizing bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If short bursts of bi-directional traffic are sent to detect active bandwidth capacity, then bandwidth detection is achieved, but user traffic is severely impacted
Solution Approach 1:
The patent introduces sequence counters and drop value calculations as intermediary mechanisms that indirectly measure bandwidth capacity without requiring actual traffic probing. By counting sequences sent and received and calculating drop values, the system determines active bandwidth capacity through computation rather than physical traffic measurement, thus avoiding impact on user traffic while achieving detection accuracy
Solution Approach 2:
The patent replaces the mechanical approach of sending actual traffic bursts with a computational method using sequence number tracking and drop value calculations. This substitution eliminates the need for physical traffic probing while maintaining the ability to detect bandwidth capacity, thereby resolving the contradiction between measurement accuracy and user traffic productivity
2Measurement precision
If traditional algorithms are used to measure WAN link loss, then measurement is achieved, but accuracy is poor due to varying clock shifts and limited scope
Solution Approach 1:
The patent implements a feedback mechanism where sequence counters at both sender and receiver ends continuously track transmitted and received sequences. The drop value calculation uses this feedback information to accurately determine loss, compensating for clock shifts by comparing sequence numbers over time intervals. This feedback-based approach significantly improves measurement accuracy and reliability compared to traditional algorithms
Solution Approach 2:
The sequence counter mechanism serves multiple functions simultaneously: it tracks packets for loss measurement, monitors bandwidth capacity, and provides timing synchronization information. This multi-functional approach eliminates the limitations of traditional single-purpose measurement algorithms, achieving both accuracy and reliability in loss measurement
3Measurement precision
If additional probing is performed to measure bandwidth capacity, then detection accuracy is improved, but network overhead and complexity increase
Solution Approach 1:
The patent enables the network components to self-measure bandwidth capacity using their existing sequence counters and packet transmission data. No external probing equipment or additional measurement devices are required - the system uses its own operational data (sequence numbers, drop counts) to calculate bandwidth capacity, thereby avoiding increased device complexity while maintaining detection accuracy
Solution Approach 2:
The existing sequence counter infrastructure is made multi-functional, serving both its original purpose of packet tracking and the new function of bandwidth capacity detection. By utilizing existing components for multiple purposes, the patent avoids adding complex probing mechanisms while achieving accurate measurement
Data Source
AI summary
In one embodiment, a method includes determining, by a first network component, a sender shaper drop value based on the following: a maximum sequence number; a minimum sequence number; and a sender sequence counter number associated with the first network component. The method also includes determining, by the first network component, a wide area network (WAN) link drop value based on the sender sequence counter number associated with the first network component and a receiver sequence counter number associated with a second network component. The method further includes determining, by the first network component, whether to adjust a sender shaper rate based on the sender shaper drop value and the WAN link drop value.