• SonicOS 7.1
• About SonicOS
  • Working with SonicOS
  • SonicOS Workflow
  • How to Use the SonicOS Administration Guides
  • Guide Conventions
• High Availability
  • About High Availability
    • High Availability Terminology
    • High Availability Modes
    • High Availability Encryption
    • Crash Detection
    • Virtual MAC Address
    • Dynamic WAN Interfaces with PPPoE HA
    • Stateful Synchronization with DHCP
    • Stateful Synchronization with DNS Proxy
    • About HA Monitoring
  • Understanding High Availability
    • Understanding SonicWall High Availability Operation Modes
    • About Active/Standby HA
  • Benefits of Active/Standby HA
    • Working of Active/Standby HA
    • About Stateful Synchronization
    • Benefits of Stateful Synchronization
  • How Does Stateful Synchronization Work?
    • Example of Stateful Synchronization
    • Active/Standby Prerequisites
  • Supported Platforms and Licensing for HA
    • Physically Connecting Your Security Appliances
    • Maintenance
      • Removing an HA Association
      • Replacing a SonicWall Security Appliance
• Replacing an HA Primary Unit
  • Replacing an HA Secondary Unit
    • High Availability Status
    • Active/Standby High Availability Status
    • High Availability Status
• High Availability Config
  • High Availability Licenses
  • Configuring High Availability
• 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
• IPv6 High Availability Monitoring
  • IPv6 HA Monitoring Considerations
  • SonicWall Support
• About This Document
  • Configuring Active/Standby High Availability Monitoring
  • IPv6 High Availability Monitoring
  • IPv6 HA Monitoring Considerations
• Azure Use Cases
  • Use Case 1: Manage Azure HA Firewall
  • Use Case 2: Forward LAN traffic to the External Network through the Gateway after HA Failover
  • Use Case 3: Configure DNAT on Azure HA Firewall
  • Use Case 4: Configure DNAT on Azure HA Firewall (Need to move multiple floating IPs support)
• SonicWall Support
  • About This Document

Virtual MAC Address

The Virtual MAC address allows the High Availability pair to share the same MAC address, which dramatically reduces convergence time following a failover. Convergence time is the amount of time it takes for the devices in a network to adapt their routing tables to the changes introduced by high availability.

Without Virtual MAC enabled, the Active and Standby Security Appliances each use their own MAC addresses. Because the Security Appliances are using the same IP address, when a failover occurs, it breaks the mapping between the IP address and MAC address in the ARP cache of all clients and network resources. The Standby Security Appliance must issue an ARP request, announcing the new MAC address/IP address pair. Until this ARP request propagates through the network, traffic intended for the Active Security Appliance’s MAC address can be lost.

The Virtual MAC address greatly simplifies this process by using the same MAC address for both the Active and Standby Security Appliances. When a failover occurs, all routes to and from the Active Security Appliance are still valid for the Standby Security Appliance. All clients and remote sites continue to use the same Virtual MAC address and IP address without interruption.

By default, this Virtual MAC address is provided by the SonicWall firmware and is different from the physical MAC address of either the Primary or Secondary Security Appliances. This eliminates the possibility of configuration errors and ensures the uniqueness of the Virtual MAC address, which prevents possible conflicts. Optionally, you can manually configure the Virtual MAC address on DEVICE | High Availability > Monitoring.

The Virtual MAC setting is available even if Stateful High Availability is not licensed. When Virtual MAC is enabled, it is always used even if Stateful Synchronization is not enabled.