Two NE80Es on a MAN are connected to an uplink router (a non-Huawei device) through double GE links. The NE80Es and the uplink router communicate using EBGP. After a cutover, the uplink traffic can be load balanced over the four GE links. However, the return traffic sent by the non-Huawei router cannot be load balanced.
The on-site Huawei technical support personnel check the traffic on the four links and find that the uplink traffic is evenly distributed across the four GE links. Also, the uplink traffic is sent by the NE80Es, so it can be decided that the problem is not caused at the NE80E side. Since the return traffic cannot be load balanced, the on-site Huawei technical support personnel check the configurations on the non-Huawei router. They find that the parameter specified in the maximum-paths command configured on the non-Huawei router is incorrect (The value is specified to be 6). Because only four GE links participate in load balancing, the value should be set to 4.
Rectify the configuration on the non-Huawei router and set the parameter to 4 in the maximum-paths command. After the rectification is complete, the return traffic can be load balanced.