Hot Standby Working Modes

This section describes the hot standby modes to help you select the right mode.

The FWs in a hot standby group support active/standby and load balancing modes.

Active/standby mode: One device is the active device and the other is the standby device. In normal cases, service traffic is processed by the active device. When the active device fails, the standby device takes over to ensure service continuity.

Mirroring mode is a special technical means to implement hot standby in active/standby mode, which is mainly used in DCN and cloud management scenarios.
Load balancing mode: The two devices back up for each other. In normal cases, the two devices share the service traffic on the entire network. If one device fails, the other device takes over all the services to ensure service continuity.

When selecting the hot standby mode, consider the following factors:

Item	Descriptions
Active/standby mode	Traffic is processed by a single device. Therefore, route planning and fault locating are simpler in this mode than in the load balancing mode.
Load balancing mode	The networking scheme and configuration are more complex in this mode than in the active/standby mode. Content security detection functions, such as intrusion prevention and antivirus, may fail in the load balancing networking due to inconsistent forward and return traffic paths. When NAT is configured on a load balancing network, additional configurations are required to prevent NAT resource allocation conflicts between the two devices. In the load balancing mode, traffic is processed by two devices. Therefore, the load balancing mode supports higher peak traffic than the active/standby or mirroring mode. When a device in load balancing mode fails, only half of the services need to be switched. Therefore, the switchover is faster than in the active/standby mode.

Item

Descriptions

Active/standby mode

Traffic is processed by a single device. Therefore, route planning and fault locating are simpler in this mode than in the load balancing mode.

Load balancing mode

The networking scheme and configuration are more complex in this mode than in the active/standby mode.

Content security detection functions, such as intrusion prevention and antivirus, may fail in the load balancing networking due to inconsistent forward and return traffic paths.

When NAT is configured on a load balancing network, additional configurations are required to prevent NAT resource allocation conflicts between the two devices.

In the load balancing mode, traffic is processed by two devices. Therefore, the load balancing mode supports higher peak traffic than the active/standby or mirroring mode.

When a device in load balancing mode fails, only half of the services need to be switched. Therefore, the switchover is faster than in the active/standby mode.