SD-WAN Redundancy: Ensuring Continuous Connectivity Across Links and Tunnels

Effective SD-WAN redundancy can help ensure that traffic connectivity is never interrupted. Here are three types of redundancies and the simplest ways to implement them.

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By Ivor Kreso
Filip Dimkovski
Edited by Filip Dimkovski

Updated May 9, 2024.

Two software developers sitting in front of a computer screen managing SD-WAN redundancies and connectivity issues

The modern business landscape hinges on the reliability of its network infrastructure, making SD-WAN redundancy a top priority for organizations seeking stability. By incorporating multiple links, diverse network paths, and sophisticated failover mechanisms, SD-WAN redundancy solutions can provide businesses with a robust safeguard against the inherent risks of link failures, equipment malfunctions, and full-scale network outages.

What Is Redundancy in SD-WAN?

Redundancy in SD-WAN is more than a backup strategy. It's a comprehensive approach designed to ensure uninterrupted network service and resilience in the face of unforeseen failures. By strategically duplicating network components and pathways, redundancy allows for a seamless transition between connections, preserving the continuity of business operations.

This advanced approach to network design transcends traditional failover systems, enabling seamless and near-instantaneous traffic rerouting that keeps mission-critical applications online. The result is a more reliable, adaptable network, engineered to support the rigorous and ever-changing demands of digital business operations.

As a concept, it encompasses various forms of duplication across the network, from physical links to encrypted tunnels, and extends to the architecture of network devices themselves to ensure that no single point of failure can disrupt the flow of data.

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Types of Redundancy in SD-WAN and How to Use Them

Link redundancy ensures network resilience by utilizing multiple communication links, such as broadband, MPLS, and cellular networks.

By having these diverse paths, the network can dynamically switch traffic to the best available route, reducing the risk of downtime and enhancing connectivity reliability.

In practice, setting up link redundancy involves configuring your network to automatically detect a downed link and switch traffic to a working alternative. This could mean balancing traffic across several ISPs or types of connections (like wired and cellular), ensuring that your data keeps flowing smoothly. The trick is in the seamless switch-over, ensuring that users don't notice when a path changes.

Tunnel Redundancy

Tunnel redundancy focuses on maintaining secure communications through multiple encrypted tunnels over the internet, such as IPSec, SSL, or GRE tunnels.

Should one tunnel, say an IPSec tunnel, become unavailable, traffic is automatically rerouted through another pre-established tunnel (such as an SSL tunnel) to ensure continuous secure data transmission.

To use tunnel redundancy effectively, you'd typically set up multiple VPN tunnels over different physical links. Automated monitoring can then help detect when one tunnel drops, instantly redirecting traffic to a backup.

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High Availability (HA) Redundancy

This implements systems and components in pairs or clusters to guarantee service continuity. In the event of hardware or software failure, a secondary system or component takes over operations with no or minimal service interruption.

For instance, if a primary server hosting application fails, a secondary server should automatically take over operations, resulting in no or minimal interruption.

In practice, implementing HA redundancy means deploying critical systems in pairs or even clusters. This could involve using specialized software that can manage the failover process automatically, ensuring your services remain available 24/7. It's especially important for systems where even a minute of downtime is too costly.

Enhancing SD-WAN Redundancy With Failover Processes

The implementation of failover processes is essential and should be designed to ensure users experience either minimal or no disruptions. This is especially crucial for maintaining the flow of communication (such as voice calls) where even minimal downtime can be noticeable and problematic.

Using Dynamic Path Selection

This feature assesses the quality of multiple WAN links in real-time, measuring latency, loss, and bandwidth to automatically direct traffic along the most optimal path. For example, if an MPLS link suddenly experiences high latency or packet loss, the SD-WAN appliance can seamlessly switch traffic to an alternate broadband or LTE link without user intervention.

Deploying IPsec VPN Tunnels

This allows for secure communication between sites. By establishing multiple VPN tunnels over different WAN links, an SD-WAN can ensure continuous data protection and access to resources, even if one of the tunnels fails. Automated monitoring tools within the SD-WAN can detect the failure of a primary tunnel and switch to a secondary, pre-established tunnel, minimizing any potential disruption to data flow.

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Ensuring Redundancy With flexiWAN

In conclusion, redundancy in SD-WAN is critical for maintaining uninterrupted network service, ensuring that businesses can withstand link failures, equipment malfunctions, and network outages. As modern enterprises rely heavily on constant connectivity for their operations, incorporating multiple links, diverse network paths, and failover mechanisms is essential for a robust network infrastructure.

flexiWAN addresses the necessity of redundancy with a comprehensive SD-WAN solution that integrates sophisticated failover mechanisms, diverse WAN links, and intelligent load balancing. This approach ensures near-instantaneous traffic rerouting, maintaining the availability of critical applications even during disruptions. By prioritizing tunnel redundancy and utilizing quality-based routing, flexiWAN proactively manages potential link degradation, offering businesses a resilient foundation for their digital initiatives and the confidence to navigate the complexities of the modern digital landscape.