Explaining SDN concepts &how NSX fits in

What is Software-Defined Networking (SDN)?

Software-Defined Networking (SDN) is an innovative networking approach that uses software-based controllers or interfaces to control how data moves through a network by talking to the hardware underneath.

Unlike traditional networks that rely on specific hardware devices like routers and switches to manage traffic, SDN uses software to create and manage virtual networks or handle regular hardware setups.

While network virtualization helps split up different virtual networks within a single physical network or connect devices on separate physical networks to create one virtual network, software-defined networking introduces a fresh way to manage how data travels by using a centralized server.

Why Software-Defined Networking is important?

SDN is a big improvement over traditional networking. Here's why:

1. Control and Speed: Instead of manually setting up multiple hardware devices, SDN lets developers manage traffic using open software. This makes networks faster and more flexible. It also allows admins to pick different hardware devices using a single protocol through a central controller.

2. Flexible Network Setup: SDN lets admins configure network services and change the network in real time from one place. This helps optimize data flow and prioritize important applications.

3. Stronger Security: SDN offers a clear view of the entire network, making it easier to spot security threats. It's better for managing smart devices connected to the internet. It can create separate zones for different security levels and isolate infected devices quickly to protect the rest of the network.

SDN differs from traditional networking in that it's software-based, not hardware-based. This makes SDN more flexible. It allows admins to control, change settings, and expand the network's capacity from one central interface without needing extra hardware.

SDN also has better security features because of its visibility and ability to set secure pathways. But securing the central controller is essential for keeping the network safe.

How does Software-Defined Networking (SDN) work?

Here are the basic ideas behind SDN:

1. Decoupling Software and Hardware: In SDN, software and hardware work separately. The control part (deciding where data goes) becomes software-based, while the hardware continues to handle the actual movement of data. This lets network administrators control the whole network through software, simplifying management.

2. Three Parts of SDN Architecture:

   • Applications: These request resources or provide network information.

   • Controllers: They decide how data should travel based on inputs from applications.

   • Networking Devices: These devices get instructions from controllers on where to send data.

3. Physical or Virtual Networking Devices: These devices move data across the network. Sometimes, virtual switches in software or hardware take over the role of physical switches, combining their functions into one smart switch. This switch checks data and directs it to the right virtual destinations.

SDN makes network control easier by separating software and hardware, allowing centralized management and smarter data movement.

Benefits of Software-Defined Networking (SDN)

Many of today’s cloud-based services and applications heavily rely on SDN. SDN ensures smooth data movement across different locations, a crucial aspect for cloud-based apps.

Moreover, SDN enables rapid movement of workloads within a network. For example, by segmenting a virtual network using Network Functions Virtualization (NFV), telecom companies can shift customer services to more cost-effective servers or even to the customer’s own servers. Service providers can swiftly move workloads between private and public cloud setups and instantly introduce new customer services using a virtual network infrastructure. SDN also simplifies the process of adjusting and expanding networks as administrators add or remove virtual machines, whether they're on-site or in the cloud.

Lastly, owing to its agility and speed, SDN supports emerging trends like edge computing and the Internet of Things (IoT), both requiring fast and seamless data transfers between distant locations.

How is SDN different from Traditional Networking?

The main distinction between SDN and traditional networking lies in their infrastructure: SDN operates on software, while traditional networking relies on hardware. SDN's software-based control plane grants it significantly more flexibility compared to traditional networks. This flexibility empowers administrators to manage the network, modify settings, allocate resources, and enhance network capacity—all through a centralized interface, without the need for additional hardware.

Security contrasts also exist between SDN and traditional networking. SDN, due to its enhanced visibility and the capability to define secure routes, offers improved security features. Nevertheless, because SDN uses a central controller, securing this controller is crucial for maintaining network security. This single point of failure could potentially pose a vulnerability for SDN.

What are the different models of SDN?

While the fundamental concept of centralized software governing data flow in switches and routers remains consistent across all forms of software-defined networking, there exist various models of SDN:

1. Open SDN: In this model, network administrators utilize protocols like OpenFlow to manage the behavior of virtual and physical switches at the data plane level.

2. SDN via APIs: Instead of employing an open protocol, application programming interfaces control data movement through the network on individual devices.

3. SDN Overlay Model: This form of software-defined networking establishes a virtual network on top of an existing hardware infrastructure. It creates dynamic tunnels between on-premise and remote data centers, allocating bandwidth across multiple channels and assigning devices to each channel, without altering the physical network.

4. Hybrid SDN: This model integrates both software-defined networking and traditional networking protocols within one environment to support various network functions. While standard networking protocols continue to manage some traffic, SDN handles other traffic, enabling administrators to gradually introduce SDN into a legacy environment in stages.