F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices High Availability Configuration Guide-6PW100

53
• Silence—The device has just started, or is transiting from synchronization state to independence
state.
• Independence—The silence timer has expired, but no failover link is established.
• Synchronization—The device has completed state negotiation with the other device and is ready for
service backup.
Figure 29 Stateful failover state relations
27B
Configuration guidelines
When you configure stateful failover, follow these guidelines:
• Stateful failover can be implemented only between two devices. The failover interfaces on the two
devices must have consistent configurations, including interface name, number of interfaces,
backup VLAN, and configuration order. If NAT is enabled on the stateful failover devices, the order
to create subinterfaces must be consistent.
• The same numbered interfaces must exist on the two devices. Otherwise, session backup fails. For
example, if Device A uses GigabitEthernet 0/1 and GigabitEthernet 0/3 to forward backup data,
Device B must also use GigabitEthernet 0/1 and GigabitEthernet 0/3.
• To run NAT on two failover devices, you must configure two identical NAT address pools for each
device. The higher-priority address pool on a device must be different from that on the other.
Otherwise, a conflict may occur during backup. For example, you can configure two NAT address
pools, 100.0.0.1 through 100.0.0.5 (Pool 1) and 100.0.0.6 through 100.0.0.10 (Pool 2), on
devices A and B. Pool 1 has a lower priority on Device A, and Pool 2 has a lower priority on Device
B. For more information, see Access Control Configuration Guide.
• Configure VRRP or a dynamic routing protocol on the failover devices and the uplink/downlink
devices to make sure that the traffic can automatically switch to the other device if one device fails.
• To implement stateful failover for portal services, you must configure portal to support stateful
failover besides the configurations described in this chapter. For detailed information, see Access
Control Configuration Guide.
• While the active device synchronizes all 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, HP recommends you to check that the configurations on the active
and standby devices are consistent before configuration synchronization.