Control plane vs. data plane

In computer networking, the term ‘plane’ describes a layer of network architecture where specific tasks that are related to network operations are performed. Planes are not actual physical components, but rather concepts that help developers and engineers understand how data traffic flows across a network. There are three kinds of networking planes:

• The control plane manages network layout.
• The data plane sends and receives data.
• The management plane configures and monitors devices that are connected over a network

Today, we’re going to look closely at the control and data planes and how they work together to increase network performance, efficiency and security.

The control plane is the part of the computer network that determines the route data will take over a network. As computer networks have become more and more integrated into modern business processes, scrutiny of network architecture—and specifically the way networking planes function—has also increased. 

The control plane uses routing protocols (algorithm-based rules) to determine the best path for information to take between network devices. One example of this practice is Multiprotocol Label Switching (MPLS), where the control plane determines the optimal route for data to travel through a network, then assigns it a unique label before sending it on to the data plane.

The data plane, also known as the forwarding plane, is the part of the network architecture responsible for moving data packets, which are small units of information that is collected for transmission over a network. The data plane controls the real-time movement of packets across the network based on routing information and protocols that it receives from the control plane.

The data plane constantly checks the routing table that’s built and maintained by the control plane for guidance on how data should be directed across the network. Based on rules in the routing table, the data plane forwards packets to the correct destination. It can also perform specific processing tasks (like updating a packet header, data about the origin and classification of information) to meet security requirements.

The control plane and the data plane both serve different purposes and perform different tasks to help modern networks function. The control plane is primarily focused on how data is routed and processed, while the data plane moves data between devices, (or nodes) on the network. Their most important differences can be summarized according to purpose, complexity and communication methodology.

Using routing protocols and network topology (essentially a map of nodes on a network) the control plane chooses a route for data to travel.

Once the correct route has been chosen, the data plane simply forwards the appropriate data packets on to their destination using instructions and following rules that have been set on the control plane.

By design, control planes are more complex than data planes. The protocols and routing paths that are determined on the control plane require complicated business logic and robust decision-making processes.

The data plane, conversely, has the relatively straightforward task of moving data around a network and its logic is comparatively simple—move data packets to their destination according to rules established on the control plane.

Finally, the methods control planes and data planes use to communicate with the systems they enable to function are different. Control planes depend on sets of rules (protocols) that govern how data can move. For example, Border Gateway Protocol (BGP), Intermediate System-to-Intermediate System (IS-IS) and Open Shortest Path First (OSPF) are all examples of popular control plane protocols.

Data planes, on the other hand, use fast, physical network connections like Ethernet and Wi-Fi to communicate.

Control planes and data planes are not physical components, but concepts that help engineers, developers and network administrators understand how data travels across a network. Both the control and data planes are conceptually located on the network layer,—the part of computer network architecture that enables devices to communicate over a network. To understand better how control planes and data planes work, let’s first look at a few key terms.

A computer network is two or more connected devices—such as desktop computers, mobile devices or routers—for the purpose of sharing resources and information. Devices that are connected over a network rely on communications protocols—rules that describe how information can be sent or received across a network, that are defined on the control plane. For example, the Border Gateway Protocol (BGP) is a common protocol that manages how data gets routed from network to network over the internet. 

Software-defined networking (SDN) is a software-controlled approach to computer network architecture that relies heavily on application programming interfaces (APIs)—sets of rules that enable applications to communicate with each other and exchange data and features. APIs can be found on both the control and data planes. APIs that manage system operations and configuration exist on the control plane while APIs that interact with actual data are part of the data plane.

Today, many enterprises are exploring SDN as a way to realize the benefits of cloud infrastructure in their approach to network management. SDN is a fast-growing market, with a valuation of USD 28.2 billion last year that is expected to grow over 17% in the next 7 years.¹

Routers and switches are physical or virtual devices that play an important role in network functionality. Routers move data packets (units of routing information that have been properly formatted) between devices that are connected over a network. Control planes enable routers to analyze data packets and determine the best route for them to take. Most routers use highly sophisticated routing algorithms to forward data packets.

Like a router, a switch can be either physical or virtual. Switches are components that enable multiple devices to be connected through the forwarding of data. Switches use Ethernet cables to move data packets between devices, allowing data and resources to be shared between users and nodes. 

The control plane performs several important functions that enable modern computer networks to operate: 

• Routing: Routing is the process of finding the right path for data to travel across a network. Routing tables—lists of various routes data can take across a network—are compiled using protocols and network topology.

• Maintaining network topology: Maintaining network topology is the task of mapping the arrangement of computers and other devices on the network. Network topology is established and maintained through a combination of physical and virtual components, such as routers and software.

• Managing traffic: After routes have been established, the control plane shapes and prioritizes network traffic to safeguard the high availability of important applications. To effectively manage network traffic, the control plane must enforce network policies that are established by network administrators.

• Load balancing: The distribution of traffic across different servers to increase system availability is a process that is known as load balancing. Many popular websites and applications receive millions of user requests a day, making load balancing a critical part of network performance.

• Clustering and high availability: The control plane is where groups of nodes are collected into clusters—connected devices that function as a single computing unit. Clustering is critical to balancing traffic and maintaining high availability, a system’s capacity to be used 100% of the time.

Once the control plane determines the route that data will travel over a network, the data plane uses logic and instructions from the control plane to move data to its destination. While much simpler in terms of design and purpose than the control plane, the data plane is no less important to network integrity and functionality.

On the data plane, network traffic passes through routers, where it is tightly controlled to protect devices from any malicious traffic, such as cyberattacks built to disrupt operations or steal information. Without the data plane, all the protocols and routes that are built on the control plane would sit idle and data packets wouldn’t be exchanged between devices on the network.

From enabling advanced technologies like cloud computing and artificial intelligence (AI) systems to function to improving application performance with features like auto scaling and provisioning, here are the top five benefits of control and data planes.

Both control planes and data planes help networks function more efficiently.

Control planes provide a single point from which every device on a network can be managed.  This allows network administrators to easily configure security settings, automate software updates and perform other important tasks, all in one location.

Data planes are designed to process massive amounts of data quickly, moving data packets between nodes on a network with minimal latency.

The control plane and data planes both help improve network performance.

The control plane enforces routing polices set by network administrators that make sure networks are performing at peak levels, while the data plane’s operational simplicity drive data travels at top speeds.

By separating the task of routing data from the task of forwarding it, control and data plane architecture allows each function to be optimized independently, adding to the overall performance of the network.

Both control and data planes are considered highly scalable, which means that more resources can be added without affecting network performance.

In the control plane, scalability is automated through a process that is known as auto scaling, the automatic provisioning of additional resources when user traffic reaches a certain threshold.

Scalability is a key feature of the data plane, as well, where its architecture makes sure that it can adapt to growing traffic demands without affecting the speed at which data travels.

Control and data planes are both highly resilient due to their design. By separating key tasks that are associated with traffic routing from tasks associated with traffic movement, the design of the control and data planes see to it that problems with one will not affect the other.

For example, if a load balancer on the control plane fails, it is unlikely that it will impact the movement of data on the data plane.

Both control and data planes help reduce latency—an important measurement of delays in a system—in several ways.

Control planes monitor device performance metrics to make sure they remain at certain levels. For example, central processing unit (CPU) latency—a measurement of the amount of time it takes data packets to move through a system.

The data plane uses technologies that increase data processing speeds, such as enhanced packet processing and machine learning (ML) algorithms. Both of these newer technologies help reduce network latency and increase system availability. 

Control planes and data planes perform vital roles in modern computer networking and underpin many valuable enterprise applications. Here are a few of the most common.

Cloud computing, the on-demand access of computing resources over the internet, has exploded in popularity, with as many as 90% of businesses worldwide adopting it by 2024.² Both control and data planes have become such an integral part of modern cloud infrastructure that specific cloud data planes and cloud control planes exist to enable enhanced functionality in cloud environments.

Cloud control planes provide management, routing and other essential features on cloud networks and cloud data planes are built to move data efficiently in cloud ecosystems. Today, all the leading cloud providers deploy cloud control planes and cloud data planes as a part of their cloud infrastructure offerings, including Cisco, Microsoft Azure and Amazon Web Services (AWS.) 

Kubernetes, one of the most widely used container platforms in the world, depends on control planes and data planes to function.

Kubernetes clusters manage nodes from the control plane that allow software code to run in any computing environment. On the data plane, specialized Kubernetes components, like kubelet and kube-proxy, handle network traffic between nodes. Kubernetes is critical to the scalability, security and efficiency modern IT infrastructures.

Virtual machines (VMs), virtual representations of a physical computers that use software instead of hardware to run programs, have become an important tool for businesses looking to reduce costs. Enterprises running VMs can gain the flexibility and scalability of a cloud environment while reducing their dependency on physical infrastructure. VMs run programs and operating systems (OS) just like a physical computer and can store and process data using virtual resources.

VMs are configured and managed on the control plane and execute computational workloads, including the running of applications, on the data plane.

Database as a Service (DbaaS) is a cloud computing solution that gives users access to databases and database software without purchasing and setting up physical components.

In a DbaaS platform, database operations are managed in the control plane, while actual compute tasks are completed on the data plane. For example, in DbaaS, the control plane is where servers are provisioned and scaled but the data plane is where the critical database queries are executed.

Artificial intelligence (AI) systems have been designed to perform tasks that would normally require human intelligence. In the last decade, AI systems have become deeply integrated into modern life, improving the functionality of many popular devices like cars, smartphones and even household appliances.

On the enterprise side, AI systems help businesses conduct smarter marketing campaigns, better utilize data and enhance automation capabilities. AI systems depend on control and data planes for running complex algorithms, performing computations and transferring data across networks.