SDN Controller Path Detection Using Selective Source Port Probing
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Solution Overview
Problem
Current data center networking technologies face scalability challenges in path detection and health monitoring due to the large number of parallel Equal Cost Multiple Paths (ECMPs) in CLOS networks, leading to inefficient probe packet generation and prolonged network health status determination.
Innovation Solution
The implementation of an SDN controller that optimizes path detection by storing path information and using a selective subset of source ports to cover all paths, reducing the number of probe packets needed and leveraging deterministic hash computation for path stability, allowing for efficient monitoring and topology change detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If probe packets are sent using all source ports to detect all ECMP paths, then path detection completeness is improved, but the number of probe packets increases exponentially leading to poor scalability
Solution Approach 1:
The patent applies partial action by selecting a representative subset of source ports rather than exhaustively probing all source ports. The SDN controller identifies and probes only enough source ports to cover all ECMP paths based on deterministic hash computation patterns, achieving complete path detection with significantly fewer probe packets than brute-force enumeration would require
Solution Approach 2:
The patent changes the approach from varying all packet parameters (source ports) to varying only necessary parameters. By leveraging deterministic hash computation, the system determines which source port parameters actually affect path selection and probes only those, reducing the search space while maintaining detection completeness
2Reliability
If probe packets are sent using all source ports to ensure all paths are covered, then path coverage is improved, but the time to determine network health status increases
Solution Approach 1:
The patent performs preliminary analysis of deterministic hash computation patterns before sending probe packets. The SDN controller pre-determines which source ports will cover all ECMP paths by analyzing the hash function behavior, allowing it to send a minimal set of probe packets that are guaranteed to cover all paths, eliminating unnecessary waiting time for exhaustive probing
Solution Approach 2:
The system uses feedback from deterministic hash computation analysis to optimize probe packet generation. By understanding how hash functions map source ports to specific paths, the SDN controller can intelligently select source ports that provide maximum path coverage information, reducing the number of probes needed and thus the time to determine network health status
3Adaptability or versatility
If the number of ECMP paths increases in large datacenters, then network capacity and redundancy are improved, but the complexity of path detection and monitoring increases
Solution Approach 1:
The patent introduces deterministic hash computation analysis as an intermediary between the SDN controller and probe packet generation. This intermediary layer analyzes the hash function behavior to predict which source ports will traverse which paths, allowing the controller to intelligently select a minimal subset of source ports that cover all ECMP paths, thereby managing detection complexity even as network capacity and path count scale
Solution Approach 2:
The patent segments the path detection problem by separating the analysis of hash computation patterns from the actual probe packet sending. The SDN controller first analyzes deterministic hash behavior to identify representative source ports, then sends probes only for those segments (source ports) that are necessary to cover all paths, dividing the complex detection task into manageable analytical and execution phases
Data Source
AI summary
In response to a path monitoring task for a particular source/destination pair, a network controller determines whether stored information includes paths for the particular source/destination pair. When the stored information includes paths for the particular source/destination pair, a subset of source ports is selected that covers all the paths for the particular source/destination pair. A probe message is sent to cause an ingress switch to send probe packets using the subset of source ports. Paths for the particular source/destination pair are computed based on received probe packets. A determination is made whether a topology for the data center network has changed by comparing the paths computed based on the receive probe packets for the particular source/destination pair with the paths included in the stored information for the particular source/destination pair.