5.3
Supporting Virtualized Network Functions with Stateful Data Plane Abstraction
SDN envisions intelligent and centralized controllers governing the forwarding behavior of dumb and low-cost switches. However, are the dumb switches a strategic choice in reality? Some dynamic applications, which only involve local states inside single links or switches, are unnecessarily centralized for easy management and programmability. Indeed, some level of control logic in switches could be handled just based on local states inside the device itself, which can efficiently offload the centralized controller from decisions.
5.4
Any virtualization technology suite you consider should be able to demonstrate reduced complexity of your network operations as a whole and not merely move the problem from one area to another.
Virtualization and use of common servers make less sense for network functions with very high-performance networking needs, such as high bandwidth load, low latency, or high predictability.
Deciding where to place a virtualized function should always include consideration of the total cost to deliver and maintain a service, the ease of scaling the service up and down, and your network’s relative agility in response to changing market conditions.
An ideal infrastructure will provide the operator with the flexibility to position and easily reposition content according to the best economics and not be constraining because of the technology in use. [good]
An infrastructure that can support the easy relocation of a virtualized function could also be critical in a case such as a service introduction through a central data center for rapid time to market.