For the topology, refer to the attachment.
The core egress of the MAN is composed of two NE80Es. NE80E_A and NE80E_B are connected through two GE links. They back up routes and traffic. A and B set up IBGP neighbor relationship through the GE interface. Simulate egress link fault of NE80E_A and test the upstream traffic of NE80E_A that passes out of the MAN through NE80E_B. There is traffic on only one GE link. The traffic is not balanced on two links.
Configure maximum load-balancing 2 and check two routes of BGP routing table. They are chosen and traffic is balanced on two GE links.
Check BGP routing table of NE80E_A. Only the routes with the next hop as *.*.*.214 are chosen, however, the routes with the next hop as *.*.*218 are not chosen. According to the selection rule of BGP, if the preceding conditions are the same, the interface with smaller IP address is chosen. By default, BGP chooses only one optimal route.
If IBGP neighbor relationship is set up through the loopback interface, load balancing can be implemented through IGP. If IBGP neighbor relationship is set up through the direct interface, load balancing can be implemented by configuring maximum load-balancing.