SD-WAN, or Software-Defined Wide Area Network, is a virtual WAN architecture that uses software-defined networking (SDN) principles to manage and optimize the performance of wide area networks. It allows organizations to securely connect users, applications, and data across multiple locations, providing improved performance, reliability, and scalability. SD-WAN simplifies network management by providing centralized control and visibility over the entire network, enabling businesses to use lower-cost Internet access to build higher-performance WANs, often replacing more expensive private WAN connection technologies like MPLS.

SD-WAN vs MPLS

The main difference between SD-WAN and MPLS is that SD-WAN is a virtualized network overlay that can combine multiple types of connections, whereas MPLS is a dedicated, hardware-based private network. SD-WAN creates encrypted tunnels over the internet, while MPLS doesn’t directly support encryption but is partitioned from the internet.

• SD-WAN: A software-defined wide area network that uses virtualization and overlay tunnels to connect users to workloads across multiple transport services and types of existing infrastructure, offering improved bandwidth availability, WAN redundancy, and cost-effectiveness.
• MPLS: A multiprotocol label switching protocol that improves performance and efficiency of data transmission in a wide area network, operating between Layer 2 and Layer 3 of the OSI model, but with higher per-megabit costs and limited flexibility.

SD-WAN is generally considered more cost-effective, flexible, and secure than MPLS, with the ability to cost-effectively mix and match network links according to content type or priority. However, MPLS is still in demand, particularly for organizations with specific connectivity and security requirements, due to its lower packet loss and dedicated leased lines. Ultimately, the choice between SD-WAN and MPLS depends on the organization’s specific needs and priorities.

SD-WAN implementation

Implementing SD-WAN involves several best practices to ensure a successful and efficient transition. Here are key steps and considerations:

1. Assess Your Network: Evaluate your current network infrastructure to identify strengths, weaknesses, and areas that require improvement. This includes understanding your network traffic patterns, application requirements, and performance goals. Assess compatibility issues with legacy systems and ensure your SD-WAN solution aligns with your business objectives.
2. Define Objectives and Strategy: Clearly define what you want to achieve with SD-WAN, such as cost savings, improved performance, or enhanced security. Align stakeholders and decision-makers on the strategic goals of the SD-WAN implementation.
3. Choose Deployment Model: Decide whether to deploy SD-WAN in-house, use a managed service provider (MSP), or a hybrid approach. Consider factors like in-house expertise, management and monitoring needs, and budget constraints.
4. Select the Right Vendor: Choose a vendor that offers robust SD-WAN solutions, including advanced security features, flexible deployment options, and strong customer support. Ensure the vendor can meet industry, country, or region-specific regulations.
5. Plan for Scalability and Flexibility: Design your SD-WAN solution to handle future growth and changing business demands. This includes considering the number of locations, size, and complexity of your network. Use modular methodologies and configuration templates to streamline deployment and management.
6. Implement Security Measures: Secure SD-WAN solutions should include advanced security features like Zero Trust Network Access (ZTNA), Intrusion Prevention System (IPS), and application-aware firewall capabilities. Ensure the SD-WAN solution can dynamically scale and adapt to different cloud environments.
7. Monitor and Troubleshoot: Implement robust monitoring tools to proactively identify and resolve performance issues. Regularly review performance metrics and network logs to ensure optimal performance and address any potential bottlenecks or security threats.
8. Ongoing Maintenance: After deployment, continue to maintain the SD-WAN network to ensure it operates efficiently. This includes regular updates, monitoring, and troubleshooting.

FortiGate SD-WAN Configuration Steps

To configure SD-WAN on a FortiGate device, follow these step-by-step instructions:

1. Enable SD-WAN Feature: Navigate to System > Feature visibility and ensure the SD-WAN option is selected.
2. Remove WAN Interfaces from Policies: Go to Policy & Objects > Firewall Policy and remove WAN interfaces from any existing policies to avoid losing internet connection.
3. Create SD-WAN Interface: Navigate to Network > SD-WAN and create a new SD-WAN interface. Click “Create New SD-WAN Member” on all ports used in SD-WAN.
4. Configure SD-WAN Members: For each WAN interface, assign the correct network gateway address. For example, set the wan1 interface Addressing mode to DHCP and Distance to 10, and set the wan2 interface IP/Netmask to 10.100.20.1 255.255.255.0.
5. Enable SD-WAN: In the SD-WAN Interface Members table, click “Create New,” select the interface, and set the appropriate gateway and cost. Set the status to Enable and click OK.
6. Configure SD-WAN Rules: Define SD-WAN rules to steer traffic based on business applications. These rules are matched in order, and the first match applies to the traffic.
7. Install Device Settings: Use FortiManager to install device settings, including creating interfaces, building VPN tunnels, and setting up BGP adjacencies. Preview the changes before installation to ensure accuracy.
8. Map Interfaces: Map your interfaces to Normalized Interfaces so that Policy Packages will install correctly.
9. Install Policy Packages: Go to Policy & Objects and click Install on the top blue bar. Preview the install before proceeding to ensure all settings are correct.