Redundant Ethernet (reth) is a three-layer virtual interface. An Ethernet redundant interface includes two member interfaces, and the types of these two member interfaces are: Ethernet interface for management. Using Ethernet redundant interface can realize the backup between the two interfaces.
As shown in Figure 1-1, m-gigabitethernet1/0/0 and m-gigabitethernet1/0/1 can be mutually backed up on the device by using Ethernet redundant interface technology. Under normal conditions, the message is forwarded through m-gigabitethernet1/0/0, and m-gigabitethernet1/0/0/1 is in the protocol closed state. When m-gigabitethernet1/0/0/0 fails, the system will automatically enable the m-gigabitethernet1/0/0/1 interface to forward messages.
The member interface of Ethernet redundant interface has two states:
Activation status: able to send and receive messages.
Inactive status: unable to send and receive messages.
The activation / deactivation status of a member interface is determined by the following factors:
When the physical state of both member interfaces is up, the member interface with higher priority is activated and the member interface with lower priority is inactive. Priority can be configured from the command line.
When the physical state of the active interface changes to down, the system will automatically activate another member interface.
When the physical state of both member interfaces is down, both interfaces are inactive.
2. Working principle of Ethernet redundant interface
At any time, only one member interface in the same Ethernet redundant interface is active. When the link of the active interface becomes down, the inactive interface will be automatically activated to replace the original active interface to send and receive messages and realize the backup between interfaces.
Ethernet redundant interface uses the bridge MAC address of the device as the MAC address, and the IP address can be configured. The equipment uses Ethernet redundant interface to communicate with upstream and downstream equipment. After receiving the message, the member interface will send it to the Ethernet redundant interface for processing. After the Ethernet redundant interface is processed, it will send it to the member interface. From the perspective of uplink and downlink devices, Ethernet redundant interfaces are connected to them. Even if the physical state of a single member interface of the Ethernet redundant interface changes, it will not affect the uplink and downlink devices.