SD-WAN Controller Adaptive QoS Policy Enforcement
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Solution Overview
Problem
Traditional wide area network (WAN) architectures face limitations in bandwidth, security, and complexity management, especially in dynamic, multi-hub or multi-datacenter SD-WAN topologies, leading to congestion and unreliable connectivity due to static QoS configurations that fail to adapt to real-time bandwidth utilization.
Innovation Solution
A centralized SD-WAN controller enforces adaptive QoS policies based on real-time bandwidth utilization across the network, dynamically adjusting bandwidth shaper ratios to prevent congestion and ensure reliable connectivity by monitoring and managing bandwidth utilization across diverse topologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If static QoS configurations are used in traditional WAN architectures, then device complexity is reduced and ease of operation is improved, but network adaptability deteriorates and congestion occurs due to inability to respond to real-time bandwidth utilization changes
Solution Approach 1:
The patent introduces an SD-WAN controller as an intermediary component that centralizes QoS policy management. The controller receives TLOC publications from edge routers, determines appropriate QoS policies based on network state, and distributes them to aggregation edge routers. This intermediary approach enables dynamic network adaptability while keeping individual router devices simpler, as the complex policy determination logic resides in the centralized controller rather than distributed across multiple routing devices.
2Productivity
If dynamic QoS policy adjustment is implemented in real-time, then bandwidth efficiency is improved and packet loss is reduced, but measurement precision requirements increase and detection difficulty rises
Solution Approach 1:
The patent implements a feedback mechanism where edge routers continuously publish TLOC information including bandwidth utilization metrics to the SD-WAN controller. The controller uses this feedback to dynamically adjust QoS policies and redistribute them to aggregation edge routers. This closed-loop feedback system enables real-time bandwidth efficiency optimization while distributing the measurement burden across multiple routers that publish their local utilization data, rather than requiring a single point to measure entire network bandwidth.
3Reliability
If centralized QoS policy enforcement is implemented across multiple aggregation edge routers, then network-level QoS control is improved and service assurance is enhanced, but device complexity and operational complexity increase
Solution Approach 1:
The patent segments the QoS control function into distinct components: the SD-WAN controller handles high-level policy determination and distribution, while aggregation edge routers handle local policy enforcement and TLOC information publishing. This segmentation allows centralized coordination for reliable service assurance while keeping individual device functionalities modular and manageable. Each aggregation edge router independently enforces received policies without requiring complex inter-router coordination, simplifying operational complexity.
4Reliability
If adaptive QoS policies are enforced based on real-time congestion indications, then congestion avoidance is improved and connectivity reliability is enhanced, but loss of information increases due to congestion indications and policy updates
Solution Approach 1:
The patent implements partial action by having edge routers publish TLOC information only when changes occur or at intervals, rather than continuously streaming all network state data. The SD-WAN controller processes these partial updates to determine QoS policy adjustments, requesting additional information only when necessary. This approach maintains connectivity reliability through timely congestion response while minimizing information overhead compared to continuous full-state reporting.
Data Source
AI summary
According to some embodiments, a method performed by a software defined wide area network (SD-WAN) controller in a SD-WAN network comprising a plurality of aggregation edge routers and a plurality of branch edge routers comprises the following steps. The method comprises: receiving, from each of the plurality of branch edge routers, a transmit location (TLOC) publication comprising a quality of service (QoS) attribute of one or more TLOCs configured on the branch edge router; determining a QoS policy based on the received TLOC publications; transmitting the QoS policy to the plurality of aggregation edge routers; receiving, from a branch edge router of the plurality of branch edge routers, a first congestion indication indicating that bandwidth utilization on a wide area network (WAN) interface of the branch edge router exceeds a first threshold; determining an updated QoS policy based on the received TLOC publications and the first congestion indication to reduce congestion at the branch edge router; and transmitting the updated QoS policy to the plurality of aggregation edge routers.