Connectivity and Synchronization between Devices
In HA mode, the Ethernet connectivity between the two devices is through a special LAN interface on each device, referred to as the Maintenance interface. Each device has its own Maintenance interface with a unique address, and each device knows the Maintenance address of the other. The Maintenance interface can use a dedicated Ethernet port group or share the same Ethernet port group with the other network interface types (i.e., OAMP, Media, and Control).
When only one of the devices is operational it is in HA stand-alone state. This means that the device has no connectivity to the second device. When the second device is powered up, it recognizes the active device through the Maintenance network and acquires the HA redundant state. It then begins synchronizing for HA with the active device through the Maintenance network. During synchronization, the active device sends the redundant device its current configuration settings, including Auxiliary files. The active device also sends its software file (.cmp) if the redundant device is running a different software version. Once loaded to the redundant device, the redundant device reboots to apply the new configuration and/or software. This ensures that the two units are synchronized regarding configuration and software.
Thus, under normal operation, one of the devices is in active state while the other is in redundant state, where both devices share the same configuration and software. Any subsequent configuration update or software upgrade on the active device is also done on the redundant device.
In the active device, all logical interfaces (i.e., Media, Control, OAMP, and Maintenance) are active. In the redundant device, only the Maintenance interface is active, which is used for connectivity to the active device. Therefore, management is done only through the active device. Upon a failure in the active device, the redundant device becomes active and activates all its logical interfaces exactly as was used on the active device.
| ● | If the active device runs an earlier version (e.g., 7.0) than the redundant device (e.g., 7.2), the redundant device is downgraded to the same version as the active device (e.g., 7.0). |
| ● | You can delay the transition from HA non-operational state, which occurs during HA synchronization between the active and redundant device, to HA operational state. This is configured by the [HAOperationalStateDelayInSec] parameter. This may be useful, for example, to delay HA switchover when using switches with spanning tree protocol (STP) that take a long time until their ports (to which the redundant device is connected) is ready. |