OpenFlow Switch Packet Sampling for Controller Load Reduction
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Solution Overview
Problem
In OpenFlow network systems, detailed flow monitoring is challenging without increasing the controller's processing load, and packet sampling methods are inadequate for monitoring small traffic flows and controlling traffic effectively.
Innovation Solution
A network system where a switch determines whether to perform sampling on received packets based on flow table settings and notifies the controller, allowing the controller to update the flow table and narrow sampling targets, enabling selective analysis of high-bandwidth flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detailed flow monitoring is performed in OpenFlow network systems, then monitoring precision is improved, but controller processing load increases
Solution Approach 1:
The patent segments the monitoring task by introducing intermediate devices (edge switches or dedicated monitoring devices) that perform initial packet sampling and filtering. These devices divide the monitoring workload from the controller, allowing detailed monitoring of specific flows while the controller only processes aggregated results or specific flow information, thus maintaining monitoring precision while reducing controller load.
Solution Approach 2:
The patent introduces intermediate devices (edge switches or monitoring devices) as mediators between the controller and the network traffic. These intermediaries perform packet sampling, flow identification, and initial analysis, then report results to the controller. This intermediary layer enables detailed flow monitoring without directly increasing controller processing load, as the intermediaries handle the bulk of processing work.
2Measurement precision
If packet sampling is performed with high probability, then traffic monitoring coverage is improved, but processing load increases
Solution Approach 1:
The patent applies local quality by performing packet sampling with different probabilities at different locations or for different flow types. Edge switches or monitoring devices sample packets locally based on specific criteria (such as flow identification, packet size, or source/destination addresses), allowing high sampling probability for specific flows of interest while maintaining lower sampling probability for other traffic, thus improving monitoring coverage for critical flows without proportionally increasing overall processing load.
3Measurement precision
If flow granularity is increased for detailed control, then monitoring precision is improved, but control complexity increases
Solution Approach 1:
The patent segments flow control into multiple hierarchical levels. Edge switches or monitoring devices handle fine-grained flow identification and initial control decisions for specific flows, while the controller manages broader policy enforcement and aggregated flow management. This segmentation enables detailed flow control precision at the edge while keeping controller complexity manageable through hierarchical decomposition of control functions.
4Measurement precision
If all packets are sampled for monitoring, then monitoring completeness is improved, but system performance deteriorates
Solution Approach 1:
The patent applies partial action by sampling only a subset of packets rather than all packets. Edge switches or monitoring devices use sampling probability mechanisms to select representative packets for analysis, ensuring monitoring completeness for statistical purposes while avoiding the performance degradation that would result from processing every packet. This partial sampling approach maintains adequate monitoring coverage while preserving system performance.
Data Source
AI summary
A network system of the present invention includes a switch and a controller. The controller sets a flow entry, in which are defined a rule and an action used to uniformly control a packet as a flow, in a flow table of the switch. The switch determines whether or not to perform a sampling processing to a received packet, in accordance with the flow table setting, and notifies the controller of a sampling result in a case where a sampling processing is performed to the received packet. The controller updates the flow table in accordance with the sampling result and narrows packets to perform a sampling processing.