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Software-Defined Networking
In this tutorial, we will learn about the Software-Defined Networking, data plane, control plane, layers of SDN, advantages, and disadvantages.
By Prerana Jain Last updated : May 05, 2023
What is Software-Defined Networking?
Software-defined architecture (SDN) is an architecture that is designed to make the network more flexible and easy to manage. This system centralizes management by abstracting the control plane from the data forwarding function in different networking devices. If we want to understand software-defined networks we have to understand the various plans involved in networking.
What is Data Plane?
The data plane enables data transfer to end from clients, handling multiple conversations through multiple protocols, and manages the conversation with remote peers. Data plan sometimes known as the user plane, forwarding planes, carrier planes, or bearer plane) it is the part of a network that carries user traffic. This plane has some fields -
- Forwarding of packets
- Segmentation and reassembly of data
- Replication of packets for multicasting
What is Control Plane?
It is the part of a network that carries signaling traffic and is responsible for routing. The main function of the control plane is system configuration and management. In other words, we can say that the control plane is the brain of the network. The activities of the control plane include -
- Making routing table
- Setting packet handling policies
In a traditional network, each switch has its data plane as well as the control plane. The control plane of various switches exchange topology in the formation and hence constructs a forwarding table which decides where an incoming data packet has to be forwarded via data plane. Software-defined networking is an approach that takes the control plane away from the switch and assigns it to the centralized unit called SDN controller. A flow table consists of match fields (like input port number and packet header) and instructions. Whenever the packet comes it is first matched against the match field to flow table entries. The instruction can be forwarding packet by one or more packets it can drop the packet or adding the headers to the packet. When the packet does not find an exact match in the flow table then switch queries to the controller and the controller sends a new entry to switch.
Layers of Software-Defined Networking
A typical SDN architecture consists of 3 layers,
- Application layer: It contains the normal network application like intrusion detection, firewall, and load balancing.
- Control layer: It contains the SDN controller which acts as the brain of the network. It also allows hardware abstraction to the application written on top of the control layer.
- Infrastructure layer: This consists of physical switches that form the data plane and carries out the actual movement of data packets.
These layers communicate via a set of interfaces called northbound APIs (between application and control layer) and southbound APIs (between control and infrastructure layer).
Advantages of Software-Defined Networking
The following are the advantages of software-defined networking:
- Separating the data plane and control plane gives the IT department an aerial view of the entire network. This makes changes much easier as you can see the effects.
- Visibility allows the IT department to make changes that can increase the speed of the entire network.
- SDN provides better security.
Disadvantages of Software-Defined Networking
The following are the disadvantages of software-defined networking:
- One of the disadvantages of an SDN network is that we eliminate the use of physical routers and switches so we don't have the security that comes with hardware.
- One of the disadvantages of SDN is distributed denial-of-service attacks.