SonicOS/X 7 High Availability

How Does Stateful Synchronization Work?

Stateful Synchronization is not load-balancing. It is an active-standby configuration where the Primary Security Appliance handles all traffic. When Stateful Synchronization is enabled, the Primary Security Appliance actively communicates with the Secondary to update most network connection information. As the Primary Security Appliance creates and updates network connection information (such as VPN tunnels, active users, connection cache entries), it immediately informs the Secondary Security Appliance. This ensures that the Secondary Security Appliance is always ready to transition to the Active state without dropping any connections.

The synchronization traffic is throttled to ensure that it does not interfere with regular network traffic. All configuration changes are performed on the Primary Security Appliance and automatically propagated to the Secondary Security Appliance. The High Availability pair uses the same LAN and WAN IP addresses—regardless of which Security Appliance is currently Active.

When using SonicWall Global Management System (GMS) to manage the Security Appliances, GMS logs into the shared WAN IP address. In case of a failover, GMS administration continues seamlessly, and GMS administrators currently logged into the Security Appliance are not logged out; however, Get and Post commands may result in a time out with no reply returned.

Synchronized and non-synchronized information table lists the information that is synchronized and information that is not currently synchronized by Stateful Synchronization.

Synchronized and non-synchronized information
Information that is SynchronizedInformation that is not Synchronized
VPN informationDynamic WAN clients (L2TP, PPPoE, and PPTP)
Basic connection cacheDeep Packet Inspection (GAV, IPS, and Anti Spyware)
FTPIPHelper bindings (such as NetBIOS and DHCP)
Oracle SQL*NETSYNFlood protection information
Real AudioContent Filtering Service information
RTSPVoIP protocols
GVC informationDynamic ARP entries and ARP cache time outs
Dynamic Address ObjectsActive wireless client information
DHCP server informationWireless client packet statistics
Multicast and IGMPRogue AP list
Active users
SonicPoint status
Wireless guest status
License information
Weighted Load Balancing information
RIP and OSPF information

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