Graphic that relates to SonicWall's High Availability firewall solution.

How SonicWall Offers High Availability at the Lowest Price

With SonicWall High Availability deployments, you’ll get a discount on the secondary unit, AND you’ll only ever pay for one set of services.


Redundancy is an indispensable characteristic of network infrastructure, and this applies to firewalls as well. Firewalls are the first line of defense in a network’s security design, protecting against unauthorized access, malicious attacks and potentially harmful traffic. Redundancy is required on firewalls to ensure high availability, fault tolerance and continuous protection even in the face of hardware failures or other issues.

What is High Availability?

High Availability is a redundancy mechanism that allows for the creation of active-passive firewall clusters. In this setup, one firewall device is actively processing traffic while the other is on standby. These configurations ensure that if one firewall fails, there is another one ready to take over, minimizing downtime and maintaining network availability.

SonicWall Enables Redundancy Without Increasing CAPEX

When selecting a firewall vendor for a redundant firewall setup, it’s critical to understand the overall cost of the solution. Some vendors may charge the same price for the secondary unit as the primary. Some may also charge for security services/subscription on the secondary box.

SonicWall does things a little differently. To help ensure the greatest degree of uptime for our end users, SonicWall provides a deep discount on the secondary box. And with SonicWall, there’s zero cost for subscription/services on the secondary box — Sonicwall shares the licenses between primary and secondary units. This means you get two devices for a subscription cost of one device, which ensures that you are protected from device and link failures without adding to the cost of your network design.

SonicWall High Availability provides organizations with a supplementary layer of network resilience and fault tolerance. By implementing this deployment, establishments can minimize downtime and maintain network security, ensuring that their critical resources and services remain accessible even in the event of unforeseen disruptions.

How SonicWall High Availability works:

  • Active-Passive Setup: In a High Availability setup, two SonicWall firewalls are deployed as a pair. One firewall acts as the primary, or active, unit, handling all network traffic and security functions. The second firewall acts as the secondary (passive) unit, which remains in standby mode, ready to take over if the primary unit fails or experiences any issues like link flapping or probe failures.
  • Stateful Synchronization: The primary and secondary firewalls continuously synchronize their configurations and session state information. This synchronization ensures that the secondary unit has real-time updates of the primary unit’s state, including active connections, so that if a failover occurs, it can seamlessly take over without disrupting existing network sessions.
  • Failover and Failback: In the event of a primary firewall failure or unavailability, the secondary firewall automatically detects this condition and initiates a failover process. During the failover, the secondary unit becomes the new active firewall, taking over the processing of network traffic and security functions. Once the primary unit is restored, it can resume its role as the active firewall, and the secondary unit returns to standby mode (failback) based on the administrator’s choice.
  • Monitoring and Detection: The SonicWall High Availability solution continuously monitors the health and availability of both firewalls in the High Availability pair, ensuring that if primary firewall experiences any critical issues, the secondary unit instantly triggers the failover process to maintain network continuity.


When evaluating firewall vendors, keep in mind the importance of redundancy, not only in your network infrastructure, but also among your firewalls. High availability for firewalls is essential to maintain continuous network protection, minimize downtime, improve performance and reduce the risk of potential security incidents and failures. With SonicWall NGFWs, redundancy is enabled and provides additional layers of resilience at the lowest additional cost.

Tiju Cherian
Senior Manager, Product Management | SonicWall
Tiju Cherian leads the firewall product management team at SonicWall. Prior to this position, Tiju held escalation and lead roles at SonicWall, Accenture and HCL. He has 16-plus years of experience in the technology space, specializing in firewalls, VPN technology, information and enterprise network security.