In dual-link MSB networking with load balancing, the new AP will connect to the AC with the lower number of connected APs. In this case, AC2 has only 20 connected APs, while AC1 has 100. Therefore, the new AP will connect to AC2 ​.

Let’s analyze the process step-by-step:

R1 redistributes the direct route 10.1.1.0/24 into OSPF .

This OSPF route reaches R2 and R3 .

R2 and R3 are in an environment that uses IS-IS towards R4 .

Both R2 and R3 re-advertise this OSPF route into IS-IS toward R4 (bidirectional route redistribution).

On R3 , a route-policy named hcip is applied to control ASE (Autonomous System External) route preference .

The ACL matches the route 10.1.1.0/24 .

The route-policy sets the preference of this ASE route to 14 .

In Huawei VRP , if a route-policy applied via preference ase route-policy matches a route, it modifies the preference value of the redistributed route when it is advertised.

By default:

OSPF ASE routes have a preference of 150 .

But in this case, due to the policy applied, the preference is explicitly changed to 14 on R3 before re-advertising to R4.

So, R4 will install the route 10.1.1.0/24 from R3 with preference 14 , assuming R2 doesn’t provide a better preference.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“You can control the preference of OSPF ASE routes by using a route-policy and applying it with the command preference ase route-policy. When the policy matches, the specified preference is used instead of the default (150).”

(Chapter: OSPF Advanced Features – Section: Route Control and Inter-AS Route Redistribution)