WAN Egress Shaper Rate Control from Sequence Counter Loss Feedback
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Solution Overview
Problem
Existing methods for detecting active bandwidth in wide area networks (WANs) for adaptive Quality of Service (QoS) involve probing that 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 adjust the shaper rate without additional probing, thereby optimizing bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional probing methods are used to detect active bandwidth, then bandwidth detection can be performed, but user traffic is severely impacted
Solution Approach 1:
The patent extracts the bandwidth detection function from active probing and implements it through passive observation of sequence counter values in existing traffic packets. By taking out the need for separate probing packets and embedding detection capabilities in normal traffic flow, the system achieves bandwidth detection without impacting user traffic.
Solution Approach 2:
The system uses the traffic packets themselves to carry the information needed for bandwidth detection. Sequence counters embedded in the packets serve both the original traffic function and the bandwidth measurement function simultaneously, making the traffic self-descriptive for measurement purposes without requiring external probing.
2Measurement precision
If traditional WAN link loss measurement algorithms are used, then link loss can be measured, but accuracy is reduced due to varying clock shifts and limited scope
Solution Approach 1:
The patent implements a feedback mechanism where the receiver measures the difference between expected and actual sequence counter values, then reports this information back to the sender. This feedback loop enables continuous refinement of bandwidth and loss measurements, compensating for clock shifts and improving both accuracy and reliability over time.
Solution Approach 2:
The patent transitions from one-dimensional loss measurement (only considering link loss) to multi-dimensional measurement by incorporating sequence counter values, timestamps, and comparison between expected and actual packet sequences. This dimensional expansion enables more accurate differentiation between link loss and clock shift effects.
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.