SD-WAN In-Line Loss Measurement via Circular Buffer Rotation
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Solution Overview
Problem
Software defined wide area networks (SD-WANs) face challenges in accurately measuring packet loss due to unpredictable internet bandwidth and infrastructure issues, leading to quality of service problems like sporadic packet loss, increased delay, and security concerns such as traffic snooping and man-in-the-middle attacks.
Innovation Solution
Implementing a method for in-line loss measurement on SD-WAN overlay paths using circular buffers with rotating roles and counters to track packet transmission and reception, allowing for precise calculation of packet loss in both forward and reverse directions, even in the presence of out-of-order traffic and varying network conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If packet loss measurement is performed using traditional methods on SD-WAN overlay paths, then measurement can be implemented, but the measurement precision is insufficient to detect losses as low as 1%
Solution Approach 1:
The patent segments the measurement process into multiple distinct phases using circular buffers with different roles (active, pre-stable, stable, post-stable). Each phase handles specific measurement tasks, allowing precise tracking of packet transmission and reception events. This segmentation enables the system to detect packet loss with 1% precision by isolating and analyzing packet flow in discrete, manageable segments throughout the measurement cycle.
2Measurement precision
If in-line loss measurement is implemented on SD-WAN overlay paths, then packet loss can be detected, but the device complexity increases due to multiple circular buffers and rotating roles
Solution Approach 1:
The patent implements dynamic role assignment for circular buffer positions, where each position cycles through four roles (active, pre-stable, stable, post-stable) in a rotating manner. This dynamic approach allows the same physical buffer structure to serve multiple measurement functions at different times, reducing the need for separate dedicated buffers for each measurement phase. The system achieves high measurement precision while managing complexity through this time-based dynamic role assignment.
3Adaptability or versatility
If traditional packet loss measurement methods are used, then implementation is simpler, but the measurement cannot account for out-of-order traffic and varying network conditions
Solution Approach 1:
The patent performs preliminary actions by pre-establishing four circular buffers with designated roles before measurement begins. The active buffer captures current packet events, while pre-stable and stable buffers prepare for and store historical data respectively. This preliminary structuring allows the system to adapt to out-of-order traffic and varying network conditions by having pre-configured buffers ready to handle different packet arrival scenarios, eliminating the need for complex real-time decision logic.
Data Source
AI summary
An advancement over previous techniques using only certain out-of-band probe PDUs to determine loss. Packet loss statistics for a SD-WAN overlay path can be calculated for every packet transmitted by one endpoint and every packet received at the other endpoint. The roles of the positions of circular buffers can be periodically rotated from active to pre-stable to stable to post-stable. Counters in the active role can be incremented whenever a packet is transmitted. A position identifier can indicate which counter to increment when the packet is received. Counters in positions that are stable can be used to produce loss statistics for the SD-WAN overlay path.