HP VPN Firewall Appliances High Availability Configuration Guide

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Active and standby interfaces
In interface backup, an interface can be an active interface or standby interface. Interfaces that can
serve as active or standby interfaces are: Layer 3 Ethernet interfaces, Layer 3 Ethernet subinterfaces,
dialer interfaces, and Tunnel interfaces. Ten-GigabitEthernet interfaces cannot serve as active or standby
interfaces.
An active interface transmits data, and can be configured with up to three standby interfaces (for
example, Serial 2/0 in Figure 79)
. Up to 10 active interfaces can be configured on a device.
Standby interf
aces function as backups for active interfaces (for example, interfaces Serial 2/1 and
Serial 2/2 in Figure 79)
, which are generally idle. One standby interface
can only back up one active
interface.
How interface backup works
Interface backup operates in active/standby mode or in load balancing mode.
Active/standby mode
As shown in Figure 80, interface Serial 2/0 on Router A acts as the active interface and interfaces Serial
2/1 and Serial 2/2 act as the standby interfaces.
Figure 80 Diagram for active/standby mode
In active/standby mode, only one interface transmits data at any given time.
• When the active interface is operating correctly, even if the traffic is overloaded, the standby
interface is in a backup state. All traffic is transmitted by the active interface.
• If the active interface fails, the standby interface with highest priority takes over to transmit data.
• When the active interface is restored, it resumes data transmission.
Load balancing mode
As shown in Figure 81, interface Serial 2/0 on Router A acts as the active interface, and interfaces Serial
2/1 and Serial 2/2 act as the standby interfaces.