SonicOS 7.1 High Availability Administration Guide
- SonicOS 7.1
- About SonicOS
- High Availability
- Replacing an HA Primary Unit
- High Availability Config
- Configuration of HA Active/Standby
- Configuring Active/Standby High Availability Settings
- Configuring HA with Dynamic WAN Interfaces
- Configuring Network DHCP and Interface Settings
- Disabling the SonicOS DHCP Server
- Configuring Virtual IP Addresses
- Configuring Redundant Ports
- Fine Tuning High Availability
- Advanced Settings
- Configuring Advanced High Availability Settings
- Monitoring High Availability
- Configuring Active/Standby High Availability Monitoring
- Configuring Active/Standby High Availability Settings
- IPv6 High Availability Monitoring
- About This Document
- Azure Use Cases
- SonicWall Support
Crash Detection
The HA feature has a thorough self-diagnostic mechanism for both the Active and Standby Security Appliances. The failover to the standby unit occurs when critical services are affected, physical or logical link failure is detected on monitored interfaces, or when the Security Appliance loses power.
The self-checking mechanism is managed by software diagnostics, which check the complete system integrity of the Security Appliance. The diagnostics check internal system statuses, system process statuses, and network connectivity. There is a weighting mechanism on both sides to decide which side has better connectivity to avoid potential failover looping.
Critical internal system processes such as NAT, VPN, and DHCP (among others) are checked in real time. The failing service is isolated as early as possible, and the failover mechanism repairs it automatically.
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