What is a Plane (in Networking)?

In networking, a “plane” refers to a distinct functional layer within the network architecture responsible for specific tasks related to network operations. Each plane focuses on a particular aspect of network functionality, helping to structure and manage the complex processes involved in network communication. These planes operate concurrently and interact with each other to ensure efficient and reliable network performance.

This blog post will continue exploring the different types of networking planes (control and data), their roles and features, and how they contribute to the overall functionality and efficiency of the network.

What is a Control Plane?

The control plane is a critical layer responsible for managing the routing and signaling functions of a network. It determines how data packets are directed through the network by building and maintaining the necessary routing tables and network topologies. This plane effectively governs the logic that decides the path data packets should take to reach their destinations.

Imagine you have a network of routers that need to communicate to determine the best path for data to travel from one point to another. The control plane does the following:

    1. Runs routing protocols to exchange information about network topology and reachable networks
    2. Builds and updates routing tables based on the exchanged information
    3. Uses this information to make decisions about the optimal path for data packets

Without the control plane, network devices would not be able to dynamically adapt to changes in the network or efficiently manage data routing, leading to potential inefficiencies and disruptions in network communication.

What is a Data Plane?

The data plane, also known as the forwarding plane, is a key networking layer responsible for the actual movement of data packets through the network. It handles the real-time processing and forwarding of packets from one network interface to another based on the rules and routing information provided by the control plane.

Consider a scenario where a packet reaches a network router: The packet enters the router through an incoming interface. The data plane then checks the routing table, built and maintained by the control plane, to determine the next hop for the packet. Based on this lookup result, the data plane forwards the packet to the appropriate outgoing interface. If necessary, the data plane may also perform additional processing, such as updating packet headers, applying quality of service (QoS) rules, or filtering based on security policies. Finally, the packet is transmitted from the router to the chosen interface towards its next destination.

Control Plane vs. Data Plane: A Breakdown

Networking planes help design, manage, and troubleshoot networks by clearly separating the different functions and responsibilities within the network architecture. Let’s break down the key functions for each type of networking plane below:

Key Functions of the Control Plane

Routing:

    • The control plane runs routing protocols (such as OSPF, BGP, and EIGRP) to exchange routing information between network devices. This process helps construct and update routing tables that the data plane uses to forward packets.
    • It determines the best paths for data to travel across the network, considering factors like network topology, link status, and traffic conditions.

Signaling:

    • The control plane handles signaling protocols that manage the establishment, maintenance, and termination of communication sessions. This includes protocols for setting up network paths and managing bandwidth allocation.
    • It manages the setup of virtual circuits and other connection-oriented services.

Topology Management:

    • It maintains an understanding of the network’s structure and state, including which devices are connected and the status of various network links.
    • The control plane adapts to network changes, such as adding or removing devices or links, and updates routing information accordingly.

Policy Enforcement:

    • The control plane enforces network policies related to routing, such as access control lists (ACLs) and quality of service (QoS) rules.
    • It ensures traffic is routed according to predefined policies, optimizing network performance and security.

Key Functions of the Data Plane

Packet Forwarding:

    • The primary function of the data plane is to forward packets from incoming interfaces to the appropriate outgoing interfaces based on the routing or switching decisions made by the control plane.
    • It looks up forwarding tables (e.g., routing tables, MAC address tables) to determine the next hop for each packet.

Packet Processing:

    • The data plane performs various packet processing tasks such as filtering, classification, queuing, and scheduling.
    • It may also involve packet header modification, encapsulation, and decapsulation.

Traffic Management:

    • The data plane manages traffic flow to ensure efficient utilization of network resources. This process includes implementing quality of service (QoS) policies, load balancing, and congestion management.
    • It prioritizes traffic based on predefined rules to meet service level agreements (SLAs) and ensures performance for critical applications.

Access Control:

    • The data plane enforces security policies by filtering traffic based on access control lists (ACLs) and firewall rules.
    • It can block or allow packets based on criteria such as source and destination IP addresses, port numbers, and protocols.

How Do Control Planes and Data Planes Work Together?

The control plane and data plane work together by dividing responsibilities: the control plane focuses on making strategic decisions about routing and policies, while the data plane handles the execution of these decisions by forwarding packets at high speed.

Let’s consider a scenario where a new network link is added. A network link is a communication pathway that connects two or more network devices, allowing them to exchange data. These links can be physical or logical and are fundamental components of network infrastructure, enabling connectivity and data transfer within and between networks.

The control plane detects the new link and runs routing protocols to integrate it into the network topology. It recalculates the routing tables to optimize paths, potentially providing shorter or more efficient routes for certain destinations. Subsequently, the control plane updates the data plane with the new routing information, modifying the forwarding tables to include paths through the new link. As a result, the data plane can immediately start using the new link for packet forwarding, ensuring optimal routing. The data plane continues forwarding packets in real time, using the updated routing tables to determine the best paths. If a packet arrives that can benefit from the new link, the data plane will forward it accordingly, based on the control plane’s updated instructions.

Use Cases for Control Planes and Data Planes

The control and data planes have distinct yet complementary roles in network operations, and their use cases reflect this division of responsibilities. Below are some common use cases for each.

Control Planes

Network Management and Configuration:

    • Centralized control planes, often found in software-defined networking (SDN), allow network administrators to manage and configure network devices from a central controller.
    • It enables automated updates and configurations across multiple devices, ensuring consistent policies and settings.

Dynamic Routing:

    • It adjusts routing tables in response to changes in the network, such as link failures or the addition of new routes.

Policy Enforcement:

    • The control plane sets policies for traffic management, quality of service (QoS), and security.
    • It distributes these policies to the data plane to ensure network traffic adheres to predefined rules and priorities.

Network Security:

    • Control planes can manage access control lists (ACLs), firewall rules, and other security policies.
    • They distribute these security configurations to the data plane for enforcement, helping to protect the network from unauthorized access and attacks.

Data Planes

Packet Forwarding:

    • The data plane’s primary function is to forward data packets based on the routing and forwarding tables provided by the control plane.
    • It ensures that packets are delivered to their destinations efficiently, with minimal delay.

Traffic Filtering and Security Enforcement:

    • The data plane enforces security policies by filtering traffic based on ACLs, firewall rules, and other security measures defined by the control plane.
    • It blocks or allows traffic according to these policies, helping to maintain network security.

Quality of Service (QoS):

    • The data plane implements QoS policies to prioritize certain types of traffic, ensuring critical applications receive the necessary bandwidth and low latency.
    • It manages traffic queues and applies scheduling algorithms to meet QoS requirements.

Load Balancing:

    • The data plane can distribute traffic across multiple links or paths to balance load and avoid congestion.
    • It uses load balancing algorithms to make real-time forwarding decisions that optimize resource utilization.

Combined Use Cases

Software-Defined Networking (SDN):

    • In SDN, the control plane is centralized in an SDN controller, which manages network policies and configurations.
    • The data plane consists of SDN-enabled switches and routers that follow the forwarding instructions provided by the controller.
    • This separation allows for more flexible and programmable networks.

Network Function Virtualization (NFV):

    • NFV leverages virtualization technologies to run network functions as software instances on standard hardware.
    • The control plane manages the deployment, scaling, and configuration of these virtual network functions (VNFs), while the data plane handles the actual data processing and forwarding.

Key Takeaways and Bonus Resources

The control plane and data plane work together by dividing responsibilities: the control plane focuses on making strategic decisions about routing and policies, while the data plane handles the execution of these decisions by forwarding packets at high speed. This separation allows for efficient and dynamic network operation, where the control plane ensures that the data plane always has the most accurate and up-to-date information to process packets effectively.

You can continue learning about control planes and data planes in relation to Couchbase via the resources below:



Author

Posted by Jeff Morris, VP Product Marketing

Jeff Morris is VP of Product and Solutions Marketing at Couchbase. He's spent over three decades marketing software development tools, databases, analytic tools, cloud services, and other open source products. He'd be the first to tell you that anyone looking for a fast, flexible, familiar, and affordable cloud-to-edge database-as-a-service can stop looking after they check out Couchbase.

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