SonicWall TZ500 Subscription Stateful HA Upgrade

TZ Service for old Appliances

SonicWall provides a range of network security products, including next-generation firewalls (NGFWs) for small to enterprise-level businesses, wireless network security, and cloud-based security solutions. Their product portfolio also includes email security, endpoint protection, and managed security services to protect against modern threats like malware and ransomware. Key technologies include their Reassembly-free Deep Packet Inspection (RFDPI) engine and an integrated suite of services like intrusion prevention, anti-malware, and application control.

The original version of SonicOS Enhanced provided a basic High Availability feature where a Backup firewall assumes the interface IP addresses of the configured interfaces when the Primary unit fails. Upon failover, layer 2 broadcasts are issued (ARP) to inform the network that the IP addresses are now owned by the Backup unit. All pre-existing network connections must be rebuilt. For example, Telnet and FTP sessions must be re-established and VPN tunnels must be renegotiated.
Stateful High Availability (SHA) provides dramatically improved failover performance. The Primary and Backup appliances are continuously synchronized so that the Backup can seamlessly assume all network responsibilities if the Primary appliance fails, with no interruptions to existing network connections.