H3C S5600 Series Operation Manual page 243

As shown in 0, Switch A has two VLAN interfaces: VLAN-interface 1 and VLAN-interface 2. The two
VLAN-interfaces back up each other. Normally. VLAN-interface 1 transmits traffic, while VLAN-interface
2 stays standby. When VLAN-interface 1 or the link connected to VLAN-interface 1 fails and thus cannot
transmit traffic normally, VLAN-interface 2 takes over to transmit traffic. In this way, the traffic can be
transmitted smoothly without interruption.
Figure 1-2 Schematic diagram for VLAN interface backup
Using Auto Detect can help implement VLAN interfaces backup. When data can be transmitted through
two VLAN interfaces on the switch to the same destination, configure one of the VLAN interface as the
active interface and the other as the standby interface. The standby interface is enabled automatically
when the active fails, so as to ensure the data transmission. In this case, the Auto Detect function is
implemented as follows:
In normal situations (that is, when the detected group is reachable), the standby VLAN interface is
down and packets are transmitted through the active VLAN interface.
When the link between the active VLAN interface and the destination faults (that is, the detected
group is unreachable), the system enables the backup VLAN interface.
When the link between the active VLAN interface and the destination recovers (that is, the detected
group becomes reachable again), the system shuts down the standby VLAN interface again.
You need to create the detected group and perform configurations concerning VLAN interfaces before
the following operations.
Follow these steps to configure the auto detect function for VLAN interface backup:
To do...
Enter system view
Enter VLAN interface view
Enable the auto detect function to
implement VLAN interface backup
Use the command...
system-view
interface Vlan-interface vlan-id
standby detect-group
group-number
1-5
Remarks
—
—
Required
This operation is only needed on
the secondary VLAN interface.