What Is SD-WAN Architecture?

5 min. read

The architecture of a software-defined wide area network is the conceptual structure and logical organization of SD-WAN. It uses a virtual overlay on WANs, centralizes control, and manages traffic.

SD-WAN architecture is a simplified way to build wide area networks. It provides rapid, reliable, and secure access to applications located anywhere, using diverse connectivity options including broadband, LTE/5G, or MPLS.

SD-WAN Architecture Explained

Diagram Depicting SD-WAN Architecture
Figure 1. SD-WAN Architecture


The architecture's virtual overlay decouples the physical network connections, which allows enterprises to retain existing WAN links while centralizing network control for real-time application traffic management.

The architectural abstraction splits the network into control and forwarding planes. The control plane is located centrally (often at an organization's headquarters) to enhance network oversight and response. This way, administrators can write rules and policies to deploy across an entire network at once.

Control in SD-WAN architecture separates from hardware to streamline network management, plus elevate service delivery and user experience. Operational guidelines from the central SD-WAN controller dictate the function of SD-WAN appliances, diminishing or removing the need for individual gateway or router management.

SD-WAN gateways, compatible with hybrid WAN, enable branch appliances to sustain multiple connections through diverse transport mechanisms, including MPLS, broadband internet, and LTE. Typically, a virtual private network (VPN) is established across each WAN connection for security enhancement.

Types of SD-WAN Architecture

Graphic depicting the three types of SD-WAN architectures, including on-premises SD-WAN, cloud-enabled SD-WAN, and cloud-enabled with backbone SD-WAN
Figure 2. Types of SD-WAN Architectures


Different SD-WAN implementations result in varying architectures. Three primary types are common:

  1. 1. On-Premises SD-WAN

    In this architecture, the SD-WAN hardware resides on-site. Network operators have direct, secure access and control over the network and hardware, offering enhanced security for sensitive information.
  2. 2. Cloud-Enabled SD-WAN

    This form of SD-WAN architecture connects to a virtual cloud gateway over the internet, enhancing network accessibility and facilitating better integration and performance with cloud-native applications.
  3. 3. Cloud-Enabled with Backbone SD-WAN

    This architecture gives organizations an extra layer of security by connecting the network to a nearby point of presence (PoP), like a data center. It allows traffic to shift from the public internet to a private connection, enhancing network security and providing a fallback in case of connection failures.

Benefits of SD-WAN Architecture

SD-WAN architecture brings a set of distinct advantages, namely:

  • Adaptive Learning

    SD-WAN architecture leverages predefined rules for traffic steering. When network conditions vary, including congestion or impairments, the architecture responds automatically in real time, ensuring optimal application performance.
  • Quality of Experience (QoEx)

    By employing multiple forms of WAN transport simultaneously, SD-WAN architecture provides a higher level of application performance, even during network impairments. The ability to manage total transport outage seamlessly enables uninterrupted operation of business-critical applications.
  • End-to-End Segmentation

    SD-WAN architecture delivers comprehensive security capabilities, orchestrating and enforcing segmentation throughout the network. Central configuration of security policies eliminates device-by-device configuration, improving operational efficiency and reducing the attack surface.
  • Secure Local Internet Breakout

    SD-WAN architecture adapts to the dynamic nature of SaaS applications, ensuring application definitions and IP addresses are updated daily, preventing interruptions.
  • Increased Bandwidth

    SD-WAN architecture optimizes network traffic, enhancing speeds while throttling low-priority applications, resulting in increased bandwidth at a lower cost.
  • Centralized Management

    A key advantage of SD-WAN architecture is its capacity for centralized control and management across branch networks. This eliminates the need for manual configuration and on-site IT staff.
  • Full Visibility

    SD-WAN architecture provides a holistic view of the network, allowing operators to monitor and manage network activities efficiently.
  • Connection Flexibility

    SD-WAN architecture permits a broader range of connection types, offering more options for vendor selection.
  • Analytics and Troubleshooting

    The architecture provides valuable insights into network performance and application issues, improving troubleshooting and reducing response time to network outages.
  • Network Agility

    SD-WAN architecture simplifies the establishment of connectivity to cloud providers, automating network infrastructure setup, and speeding up deployment.

Overall, SD-WAN architecture combines multiple functionalities into a single, centrally managed platform, resulting in a network that's adaptable, secure, and easier to manage.

Components of SD-WAN Architecture

Technical diagram depicting the role of SD-WAN components
Figure 3. SD-WAN Components


The architectural components of a software-defined wide area network include multiple interlocking pieces that collectively create an intelligent, dynamic, and efficient network management system.


The SD-WAN edge is essentially the network's frontier where the endpoints reside. These endpoints could be anything from a branch office to a remote data center or a cloud platform. The edge is significant as it becomes the ingress and egress point of the network, determining how data enters and leaves the system.

SD-WAN Orchestrator

The SD-WAN Orchestrator serves as the network's virtual manager. It is responsible for overseeing traffic flow, applying policies and protocols set by network operators. This component provides a centralized platform for operational control, reducing manual intervention and increasing network efficiency.

SD-WAN Controller

The SD-WAN Controller serves as the network's administrative hub, responsible for centralizing network management. It provides operators with a single-pane view of the network, enabling them to set policies for the orchestrator to execute.

Virtual or Physical Nodes

These are new additions that augment the underlay WAN. These nodes, either physical or virtual, can add additional capabilities or capacity to the existing network. They contribute to a more robust, responsive network.

SD-WAN Deployment

SD-WAN Deployment Models

SD-WAN deployment models are primarily determined by the organization's network and business requirements. An organization may opt for one of three deployment models:

  1. 1. Do-it-yourself (DIY)

    The organization purchases the SD-WAN solution directly from a vendor and manages all aspects of deployment and system management internally.
  2. 2. Fully Managed

    The organization delegates the entirety of the SD-WAN deployment and management process to a Managed Service Provider (MSP).
  3. 3. Co-managed or Hybrid

    Here, the organization retains control over certain aspects of the SD-WAN management while outsourcing the remainder to an MSP.

The choice between these models primarily depends on the organization's size and the capabilities of its IT team.

SD-WAN Deployment Form Factors

Graphic depicting the three SD-WAN form factors: physical appliance, virtual, and cloud
Figure 4. SD-WAN Deployment Form Factors


The SD-WAN architecture includes various form factors:

  • Physical Appliance:

    A device installed on-premises at locations such as branch offices or data centers.
  • Virtual:

    A virtual machine set up on universal customer premises equipment or servers at branch locations.
  • Cloud:

    This version of SD-WAN is operated using software situated in a cloud environment.

SD-WAN Implementation

SDWAN Implementation

Step 1: Requirements Gathering

Before implementing an SD-WAN architecture, it's crucial to gather and document the functional and nonfunctional requirements. While cost reduction is often a driving factor, organizations should also consider factors like improved network resilience, tightened security, and more agile business processes. These requirements should reflect the strategic initiatives of the organization.

Step 2: Site Profiling

A successful SD-WAN implementation requires identifying different site types within the network based on the connectivity requirements, application traffic flows, quality of service, bandwidth, and security needs. Minimizing the variety of site types can enhance network consistency, improve automation, and reduce configuration complexity. Sites may be categorized into offices, manufacturing facilities, warehouses, engineering design facilities, or corporate data centers, each with its own unique requirements.

Step 3: Proof-of-Concept Site Selection

Identify proof-of-concept (PoC) sites based on their significance in your network architecture. As part of this step, order the corresponding test circuits for these sites, taking into account the lead time for circuit procurement. Be sure to carefully evaluate the carrier architectures and incorporate packet loss measurement in the service-level agreements.

Step 4: Product Evaluation

Product evaluation should commence with a review of potential solutions in the market. Criteria for selection should be developed, bearing in mind that the market dynamics change quickly with new product features released periodically. Also, it's important to remember that the protocols used for SD-WANs are proprietary and do not support interoperability between products from different vendors.

Step 5: PoC Testing

Begin hands-on evaluation with the PoC in the lab. This should include traffic generation and monitoring functions. Policy mechanisms, zero-touch provisioning, traffic handling policies, SD-WAN interface, visibility provided by the monitoring system, and security measures should all be evaluated. This is a crucial phase to understand the capabilities and limitations of the product.

Step 6: SD-WAN Deployment Model Selection

Identify the appropriate deployment model. This could involve hardware deployment at each site, or a virtual implementation requiring a virtual machine host. Zero-touch provisioning should also be considered as it simplifies the deployment process. Validate the implementation and the deployment model in the production environment by extending the PoC from the lab to a low-risk production site.

Thoroughness in each of these steps will ensure a smoother transition to production implementation. An SD-WAN implementation can revolutionize the network performance, agility, and cost efficiency of an organization, but it must be implemented correctly. By following these steps, an organization can move toward a successful SD-WAN implementation.

SD-WAN Architecture Security

SD-WAN security requires robust technologies. SD-WAN employs IPsec for network traffic authentication and integrates protection from security vendors.

Microsegmentation serves as a core SD-WAN security element, which isolates and prioritizes network traffic. Unidentified traffic undergoes routing through security tools for scrutiny. High-priority traffic adheres to designated links to enhance security and efficiency.

Encryption also fortifies SD-WAN security. Both the data and control plane benefit from encryption, thwarting unauthorized access and securing data transmission.

SASE, a decentralized network technology, plays a transformative role in SD-WAN security. Instead of a traditional hub-and-spoke topology, SASE forms secure connections with users regardless of location. This approach augments security measures and broadens networking functions.

SD-WAN underpins many security best practices. It facilitates the introduction of Zero Trust network access (ZTNA), a key element in modern cybersecurity strategies. In this arrangement, the network serves as an effective policy enforcement point, granting control over security requirements related to zone boundaries.

Managing security complexity is crucial in the SD-WAN context. As microsegmentation and granular identity and access management (IAM) become ubiquitous, the need for automation and software-based solutions intensifies. These methods streamline IAM, making it more efficient and manageable.

Overall, SD-WAN significantly enhances network security. It establishes firm policy enforcement points, enabling the application of advanced security measures. This fortified network infrastructure is instrumental in preserving the network's safety and integrity.

Future of SD-WAN Architecture

SD-WAN architecture is central to the transition to cloud-based solutions, particularly in multicloud environments. This shift aligns with the trajectory of SASE architecture, creating the opportunity for potential incorporation of SD-WAN into broader, cloud-based security strategies.

In addition to SASE integration, SD-WAN offerings could also benefit from artificial intelligence for IT operations (AIOps). AIOps can automate anomaly detection, event correlation, and root cause analysis, thereby facilitating quicker issue identification and resolution by IT administrators.

The potential of SD-WAN technology further extends into the IoT realm. A symbiosis between SD-WAN and IoT devices could enhance data transmission efficiency and improve the centralized management of dispersed IoT devices.

Parallel to these advancements, cellular technologies such as 4G and 5G are becoming increasingly integrated into WANs. Not only do these technologies enhance network performance and reliability, but they also offer a solution in areas where wired connections are lacking or unreliable. In many cases, these cellular connections serve as primary links, further cementing their significance in WAN implementation.

The integration of SD-WAN in wireless WANs enables the extension of various capabilities to cellular connections. As a result, potential future network designs are evolving toward hybrid WAN solutions, which blend MPLS links, wireline broadband, 4G, and 5G.

SD-WAN Architecture FAQs

  1. On-premises
  2. Cloud-enabled
  3. Cloud-enabled with a backbone
SD-WAN includes several critical components:

  • SD-WAN edge
  • SD-WAN orchestrator
  • SD-WAN controller
  • Virtual or physical Nodes
SD-WAN (software-defined wide area networking) is a type of networking technology that uses software-defined networking (SDN) principles to manage and optimize the performance of wide area networks (WANs).

SD-WAN is a virtualized service connecting and extending enterprise networks across large geographical areas using diverse links such as MPLS, wireless, broadband, VPNs, and the internet. Unlike traditional WANs that require manually written rules and policies for router configuration, SD-WAN provides an automated, software-based solution for managing different types of traffic and conditions in real-time.

Its architecture features a centralized control plane that routes traffic and deploys policies across the entire network, moving control away from the hardware for simplified management. SD-WAN gateways facilitate hybrid WAN, enabling each appliance to support multiple connections via different transport means, with VPNs installed for security.

The interchangeability of different connection types enhances network bandwidth, performance, redundancy, and centralization, minimizing individual gateway and router management.
SD-WAN operates at the network layer, which is Layer 3 of the Open Systems Interconnection (OSI) model. It manages network routing, taking advantage of software-defined networking to intelligently distribute traffic across a wide area network. However, it's important to note that while SD-WAN primarily functions at Layer 3, it's a sophisticated technology that can also understand and make decisions based on Layer 7 (application layer) information.
SD-WAN leverages several protocols, not just a single one. Its operation involves a variety of networking protocols at different OSI model layers.

For transport, it typically uses IPsec (Internet Protocol security) for secure, encrypted communications, and it often employs MPLS (multiprotocol label switching), LTE, broadband, and other methods for transmitting data over wide areas.

On the higher OSI layers, it may use HTTP/HTTPS and other application-layer protocols, depending on the nature of the traffic.

It's worth noting that SD-WAN can intelligently select the best transport method based on current network conditions and the needs of the specific data transmission.