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
Stateful Synchronization with DHCP
DHCP can be enabled on interfaces in both Active/Standby non-stateful and Stateful Synchronization modes.
Only the Active Security Appliance can get a DHCP lease. The Active Security Appliance synchronizes the DHCP IP address along with the DNS and gateway addresses to the Standby Security Appliance. The DHCP client ID is also synchronized, allowing this feature to work even without enabling Virtual MAC.
During a failover, the Active Security Appliance releases the DHCP lease and, as it becomes the Active unit, the Standby Security Appliance renews the DHCP lease using the existing DHCP IP address and client ID. The IP address does not change, and network traffic, including VPN tunnel traffic, continues to pass.
If the Active Security Appliance does not have an IP address when failover occurs, the Standby Security Appliance starts a new DHCP discovery.
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