Overview
Direct Answer
Software-Defined Networking (SDN) is an architecture that decouples network control logic from underlying data forwarding hardware, enabling centralised management through software controllers. This separation allows dynamic reconfiguration of network behaviour independent of physical infrastructure.
How It Works
SDN uses a control plane (software controller) communicating with a data plane (network switches and devices) via standardised protocols, typically OpenFlow. The controller maintains a global view of the network topology and issues forwarding rules to switches, which then execute packet routing and handling decisions without local intelligence.
Why It Matters
Organisations benefit from reduced capital expenditure by commoditising switching hardware, improved network agility through programmatic policy changes, and simplified multi-tenant isolation in cloud environments. Rapid provisioning and dynamic traffic engineering address the limitations of traditional distributed routing protocols.
Common Applications
SDN deployment is prevalent in data centre networking for VM mobility and load balancing, wide-area network optimisation across enterprise branch offices, and network virtualisation in cloud computing platforms. Telecommunications providers utilise SDN for service chaining and mobile network slicing.
Key Considerations
Controller reliability becomes a single point of failure requiring redundancy; latency-sensitive applications may suffer if centralised control decisions introduce delays. Security models must account for controller compromise and the extended attack surface created by management interfaces.
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