Hierarchical SDN Control for Scalable Wide Area Networks
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Solution Overview
Problem
Conventional software-defined networks (SDNs) face limitations in scalability and latency due to centralized control methodologies, which restrict their application to small-scale networks and make it difficult to manage wide area networks comprehensively.
Innovation Solution
A distributed control system with a hierarchy of regional and root controllers is employed, where regional controllers manage local network maps and root controllers maintain global maps, enabling scalable and latency-tolerant network management across regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a centralized control methodology is used in SDN, then network management is simplified and centralized, but the number of network devices that can be supported is limited
Solution Approach 1:
The centralized controller is segmented into multiple regional controllers, each managing a specific geographic region or network segment. This allows the system to scale by adding more regional controllers without requiring a single monolithic controller to handle all devices, thereby increasing the number of supported network devices while maintaining centralized management capabilities through hierarchical coordination.
Solution Approach 2:
The system transitions from a single-dimensional centralized control model to a multi-dimensional hierarchical control structure with regional controllers at one level and root controllers at another. This dimensional change enables the system to manage larger numbers of devices by distributing control across multiple levels and geographic regions.
2Loss of time
If the network map is updated rapidly to reduce latency, then route determination is faster, but it becomes difficult to achieve rapid updates in conventional SDN
Solution Approach 1:
The global network map is segmented into multiple regional network maps, each maintained by a regional controller for its respective region. This segmentation allows parallel updates of regional maps without requiring coordination across the entire network, enabling faster update speeds while reducing latency for local route determinations.
Solution Approach 2:
Regional controllers pre-calculate and maintain route information for their respective regions in advance. When a routing decision is needed, the information is already prepared and available locally, eliminating the need for real-time calculations across the entire network and thereby reducing latency.
3Adaptability or versatility
If regional controllers maintain local network maps, then scalability is improved, but coordination and synchronization between controllers becomes more complex
Solution Approach 1:
The control function is segmented into regional controllers that independently manage local network maps, improving scalability. The hierarchical structure with root controllers provides a simple coordination mechanism where regional controllers only need to communicate with their parent root controller, rather than requiring complex peer-to-peer coordination between all controllers.
Solution Approach 2:
Root controllers act as intermediaries between regional controllers, simplifying coordination. Instead of regional controllers needing to directly communicate and synchronize with each other, they interact through the root controller layer, which handles global coordination and synchronization tasks.
Data Source
AI summary
System and method of providing SDN network service management by use of a distributed control system that comprises a hierarchy of controllers. The distributed control system includes regional controllers and one or more root controllers. A respective regional controller is configured to control a set of network devices and maintain regional network map related thereto. A respective root controller is configured to control a group of regional controllers and maintain a global network map across regions of the SDN. The root controllers can synchronize the global network map with each other and its subordinate controllers. A root controller may not be activated for packet transmission route determination unless its subordinate regional controller is unequipped with sufficient information to determine a requested route.