To address the issue, Huawei performed the following operations and observed the following information:
1. Checked the core network side and did not find related alarms.
2. Cleared all the port statistics of NE40 and then counted packets at ports. Found the number of lost packets in an MP-group kept increasing, while the situation did not occur on the other MP-groups.
3. Confirmed that 21 E1 links were working properly and excluded the assumption that the issue was caused by decreased transmission bandwidth.
4. Viewed the traffic statistics on the NMS and found that the traffic volume in the three MP-groups kept a proportion of 1.2:1:1.
5. Confirmed that NE40 was unable to implement load balancing by packet over three next-hop links and the actual proportion of traffic over the three links was 1.2:1:1. When the transmission bandwidth of the three MP-groups was the same, one MP-group started to discard packets once the traffic volume to be transmitted was higher than 88.67% of the total bandwidth provided by the three MP-groups.
6. Added one E1 link to the MP-group carrying traffic 1.2 times that of the other MP-groups according to the proportion. The method applies only to a fixed service model. The load balancing proportion was determined by hash algorithm based on destination IP addresses, and therefore the service model was likely to change frequently and the MP-group carrying traffic 1.2 times that of the other groups would not be determined . The method in this case did not work.Alternatively, set the voice call limit on the UMG according to the 88% of the total bandwidth provided by the three MP-groups.