SCALABILITY PROBLEMS OF SOFTWARE-DEFINED NETWORKS

DOI: 10.31673/2786-8362.2025.013075

Abstract

Softwaredefined networking (SDN) has enormous potential to transform network infrastructure, but there are
significant challenges on the road to widespread adoption. And scalability is a key challenge. Given the
rapid growth in data volumes, the number of connected devices, and bandwidth requirements, the ability of
SDN to scale effectively is critical. If an SDN controller cannot cope with a large number of devices and
data flows, this can lead to performance degradation, latency, and even network failures. Research
initiatives aimed at addressing scalability issues in SDN are extremely relevant. These could include
developing more efficient flow control algorithms. This would allow the controller to handle a larger
number of requests without compromising performance. Addressing the scalability issue, along with other
issues such as security, legacy compatibility, and management complexity, is key to realizing the full
potential of software-defined networks and providing operators with the efficient, flexible, and scalable
infrastructure they need. SDN scalability studies show that these problems are often not caused by SDN
and are not fundamentally unique to it, and most of these problems can be solved without losing the benefits
of SDN. If a network has tens of thousands of switching elements and can grow rapidly, the sheer number
of control events generated in any network of this scale is enough to overwhelm any centralized controller.
One way to solve this problem is to proactively enforce rules on the switches, effectively eliminating most
control requests before they reach the control plane. Nodes in SDN networks can be geographically
distributed, and the large diameter of these networks exacerbates the scalability problems of controllers.
Physical partitioning of the network can be used to divide it into separate regions; each partition can be
managed by an independent controller, and these controllers can exchange only the necessary state change
events, effectively hiding most events from external controllers.
Keywords: Software-defined network (SDN), SDN controller, scalability, performance, control
plane, data plane, ASIC, Open vSwitch

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