Huawei network devices support two Eth-Trunk working modes:
l Manual load balancing mode
l LACP mode
In manual load balancing mode, an Eth-Trunk is manually created, and its member interfaces are manually configured. LACP is not used for negotiation between the two systems.
In most cases, all links are active links. In this mode, all active links forward data and evenly share traffic. Therefore, this mode is called load balancing mode.
If an active link is faulty, the LAG automatically evenly shares traffic among the remaining active links.
If one of the devices at both ends of a LAG does not support LACP, you can use the manual mode. 
Defects of the Manual Mode
In manual mode, devices do not exchange packets. Therefore, the configuration needs to be manually confirmed.
As shown in the following figure, four interfaces of SW1 are added to an Eth-Trunk, but the peer end of one interface is SW3 instead of SW2. In this case, some traffic is load balanced to SW3, causing communication exceptions. 
So to ensure that the Eth-Trunk works properly, ensure that the peer interfaces of all member interfaces in the Eth-Trunk meet the following requirements:
l The peer interfaces reside on the same device.
l The peer interfaces are added to the same Eth-Trunk.
2. In manual mode, the device can determine whether the peer interface is working properly based only on the physical layer status.
As shown in the following figure, when a member interface of SW2 is in UP state but cannot forward packets, SW1 cannot detect the faulty and still sends data through four interfaces, causing communication exceptions.
Example for Configuring eth-trunk in manual load balancing mode
The basic configuration commands are as follows:
# Create an Eth-Trunk aggregation interface.
[Huawei] interface eth-trunk 1
[Huawei-Eth-Trunk1] mode manual load-balance
Note: The mode manual load-balance command sets the working mode of the aggregation interface to manual load balancing. Devices at both ends of an aggregated link must work in the same mode.
# Add physical member interfaces GE0/0/1, GE0/0/2, and GE0/0/3 to the Eth-Trunk.
[Huawei] interface GigabitEthernet0/0/1
[Huawei-GigabitEthernet0/0/1] eth-trunk 1
[Huawei] interface GigabitEthernet0/0/2
[Huawei-GigabitEthernet0/0/2] eth-trunk 1
# (Optional) Configure load balancing mode.
[Huawei-Eth-Trunk1] load-balance { src-dst-mac | src-dst-ip | packet-all }
# (Optional) To ensure the status and bandwidth of an Eth-Trunk interface, you can set the threshold (default value: 1) for the number of active interfaces to reduce the impact of member link status changes. The lower threshold for the number of active interfaces is set to ensure the minimum bandwidth. When the number of active interfaces is less than the lower threshold, the Eth-Trunk interface goes down.
[Huawei-Eth-Trunk1] least active-linknumber link-number
# Configure connection parameters.
For example, configure SW1 and SW2 are to communicate with each other through VLAN10 and VLAN20.
[Huawei-Eth-Trunk1]port link-type trunk
[Huawei-Eth-Trunk1]port trunk allow-pass vlan 10 20
