H3C Technologies H3C SecPath F1000-E - Manual (Page 851)

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Figure 2 Network diagram for stateful failover
Internet
Internal
network
Device A
Host A Host B
Device B
Failover link
GE0/1 GE0/1
GE0/0 GE0/0
GE0/2 GE0/2
Service backup
The two devices exchange state negotiation messages through the failover link periodically. After the
two devices enter the synchronization state, they back up the services of each other to ensure that the
services on them are consistent. If one device fails, the other device can take over the services using
VRRP or dynamic routing protocols (such as OSPF) to avoid service interruption.
Configuration synchronization
To implement service backup, the key service configurations on the two devices must be consistent. With
the configuration synchronization function, you can synchronize such configurations from the active
device to the standby device through the failover link, instead of making repeated configurations on
both devices.
You can use the following synchronization methods:
• Auto synchronization. With auto synchronization, the active device synchronizes all its
configurations to the standby device at a time. After that, when its configuration is changed, the
active device automatically synchronizes the new configuration to the standby device.
• Manual synchronization. You can choose to manually synchronize all configuration.
CAUTION:
While the active device synchronizes all its configurations to the standby device, the redundant
configurations (if any) on the standby device are not removed. This may result in a synchronization
failure. To avoid this problem, you are recommended to check the configurations on the active and
standby devices, and enable auto synchronization.
Introduction to Stateful Failover States
The stateful failover states include:
• Silence: Indicates that the device has just started, or is transiting from synchronization state to
independence state.
• Independence: Indicates that the silence timer has expired, but no failover link is established.