Christo Briedenhann

In a world of shrinking IT budgets and changing technology, it’s imperative that businesses reduce operational costs, while also improving flexibility and agility. Therefore, virtualisation in the data centre is definitely worth considering. Software-Defined Networking-based (SDN) virtual networks can provide businesses with the tools they need to deliver applications effectively while also simplifying the underlying physical infrastructure.

The physical network has suffered from certain limitations that constrain its potential, particularly in this modern age of mobility and on-demand computing. Physical network components essentially consist of hardware devices of fixed sizes and capacities that are wired together in static topologies. On-demand reallocation of network resources in a hardware-based environment is nearly impossible, and applications often must conform themselves to the network. The result is a less than ideal functionality for users, and management challenges for IT personnel.

In a fully virtualised network the control logic is decoupled from the network’s underlying physical hardware. The physical network components retain their packet forwarding duties, but control and decision-making abilities are liberated from the device’s “bounding box.” Instead, these functions are implemented as software-based services that freely adapt to the changing circumstances of network traffic, encompass all segments, track state changes throughout the entire network, and adapt policy enforcement mechanisms like QoS according to application requirements.

Software-defined networking (SDN) is rapidly becoming the preferred method to build virtualised networks for businesses today, as it establishes a framework to create a virtualised network that appears to upper-layer services, such as operating systems and applications, as though it were an ordinary physical network. This allows services and applications to be provided without needing to be configured for a different environment.

Building a virtual network without using SDN is certainly possible, but it is probably not as useful. However, sophisticated state management becomes a challenging technical problem when logical networks could be located just about anywhere. Without the state management capabilities that are afforded by SDN, the operational utility of network virtualisation diminishes considerably.

About the author: Christo Briedenhann" rel=tag>Christo Briedenhann, regional director at Riverbed Technology