SDN/OpenFlow

The control plane is (1) logically centralized and (2) decoupled from the data plane.

OpenFlow is an open API that provides a common instruction set for interacting with packet--‐forwarding hardware.

Need for SDN:

Network Virtualization (Data Center & Cloud)– Use network resource without worrying about where it is physically located, how much it is, how it is organized, etc.

OpenFlow Switch:

Consists of one or more flow tables, group table  and meter table.
A single switch can be managed by one or more controllers.
The flow tables and group table are used during the lookup or forwarding phase in order to forward the packet to appropriate port.
Meter table is used to perform simple QOS operations like rate-limiting to complex QOS operations like DiffServ etc