Hot Standby Optional Configurations

The optional configurations of hot standby refer to the items that need to be configured by default or in special scenarios. Set the optional configurations according to actual situations.

Item	Command	Description
Interval at which VGMP, HRP heartbeat, and HRP link detection packets are sent	hrp timer hello interval	To prevent incorrect switchover between the active and standby FWs, do not set the interval to a too small value. The default interval 1000 ms is recommended. To change this value, ensure that the intervals specified on active and standby FWs are the same. Otherwise, the active/standby status of the FWs may change by error.
Preemption function and preemption delay of the VGMP group	hrp preempt [ delay interval ]	The preemption function of the VGMP group is enabled by default, and the default preemption delay is 60 seconds. For details about how to configure the preemption function of a VGMP group, see Proactive Preemption.
Enabling the standby device.	hrp standby config enable	This command can be configured on both active and standby devices, so that the devices can back up each other. If this command is configured on both active and standby devices, the later configuration overrides the previous one. By default, this function is disabled. All information that can be backed up can be configured only on the active device, not on the standby device. After this function is enabled, all the information that can be backed up can be directly configured on the standby device, and the configurations on the standby device can be synchronized to the active device. If conflicting settings are configured on the active and standby devices, the later setting overrides the previously one.
TCP session status detection delay	hrp tcp link-state check delay delay-time	When the upstream and downstream service interfaces on the FW work in hot standby mode at Layer 2 and TCP session status detection is enabled on the FW, run the hrp tcp link-state check delay command on active and standby FWs to set a delay for TCP session status detection. Otherwise, the new active device upon a switchover cannot establish sessions because it cannot immediately learn the MAC address table. After a delay (delay-time) is set, TCP session status detection is postponed on the new active FW after a switchover, ensuring that the new active FW has enough time to learn the MAC address table. By default, TCP session status detection is not delayed.
Encrypting the configuration command backup packets transmitted between the active and standby devices	hrp encryption-key key	When the heartbeat interfaces of the two FWs are not directly connected, you are advised to run this command to set an encryption key for security. You need to configure the key on both active and standby FWs. Ensure that the keys on the two FWs are the same. Otherwise, backup between the FWs may fail. By default, backup packets are transferred in plain text.
Priority of the IP header of heartbeat packets	hrp ip-packet priority priority-number	A larger priority-number value indicates a higher priority. The packets with higher priorities are preferentially forwarded. The default priority of the IP header is 6.