Different Models of SDN
There are several models, which are used in SDN:
- Open SDN
- SDN via APIs
- SDN via Hypervisor-based Overlay Network
- Hybrid SDN
1. Open SDN: Open SDN is implemented using the OpenFlow switch. It is a straightforward implementation of SDN. In Open SDN, the controller communicates with the switches using south-bound API with the help of OpenFlow protocol.
2. SDN via APIs: In SDN via API, the functions in remote devices like switches are invoked using conventional methods like SNMP or CLI or through newer methods like Rest API. Here, the devices are provided with control points enabling the controller to manipulate the remote devices using APIs.
3. SDN via Hypervisor-based Overlay Network: In SDN via the hypervisor, the configuration of physical devices is unchanged. Instead, Hypervisor based overlay networks are created over the physical network. Only the devices at the edge of the physical network are connected to the virtualized networks, thereby concealing the information of other devices in the physical network.
4. Hybrid SDN: Hybrid Networking is a combination of Traditional Networking with software-defined networking in one network to support different types of functions on a network.
Software defined Networking(SDN)
SDN stands for Software Defined Network which is a networking architecture approach. It enables the control and management of the network using software applications. Through Software Defined Network (SDN) networking behavior of the entire network and its devices are programmed in a centrally controlled manner through software applications using open APIs.
To understand software-defined networks, we need to understand the various planes involved in networking.
- Data Plane
- Control Plane
Data plane: All the activities involving as well as resulting from data packets sent by the end-user belong to this plane. This includes:
- Forwarding of packets.
- Segmentation and reassembly of data.
- Replication of packets for multicasting.
Control plane: All activities necessary to perform data plane activities but do not involve end-user data packets belong to this plane. In other words, this is the brain of the network. The activities of the control plane include:
- Making routing tables.
- Setting packet handling policies.