Why cannot interfaces of different types generate equal-cost routes and establish OSPF load balancing

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OSPF can automatically calculate the cost of an interface based on the interface bandwidth. The calculation formula is: Interface cost = Bandwidth reference value/Interface bandwidth. The bandwidth reference value is configurable. The default value is 100 Mbit/s. Routes generated by OSPF have the same priority (10 by default). The interface cost, however, depends on the interface type. Interfaces of different types have different costs; therefore, the interfaces cannot generate equal-cost routes, leading to failure in establishing load balancing.

Other related questions:
Why the ASBR does not generate equal-cost route
Two areas are configured on two devices separately, for example: SwitchA: area 0: 10.5.5.5 area 1: 10.4.4.4 SwitchB: area 0: 10.5.5.6 area 1: 10.4.4.6 Adjacencies are formed on the devices separately. Thus, the next-hop of a route that SwitchB learns from SwitchA should be 10.5.5.5 or 10.4.4.4. However, the route on SwitchB goes through only 10.4.4.4 in area 1 as the gateway and no load sharing can be performed. This is because when multiple equal-cost routes exist, an ASBR selects the route with the greatest area ID.

Modifying the number of equal-cost OSPF routes on the USG6000 series
Perform as follows to configure the maximum number of equal-cost OSPF routes on the USG6000 series: 1. In the user view, run the system-view command to enter the system view. 2. Run the ospf [ process-id ] command to access the OSPF process view. 3. Run the maximum load-balancing number command to configure the maximum number of equal-cost routes. A maximum of eight equal-cost OSPF routes are supported.

How does S series switch implement load balancing among equal-cost routes
An S series switch supports enhanced equal-cost multipath (ECMP) load balancing mode. This function mitigates the problem of unequal traffic distribution among equal-cost routes. If this problem still occurs, configure a traffic policy to redirect the traffic with the highest rate to the link with the lightest traffic. Perform the following operations to configure a traffic policy: 1. Configure redirection. [HUAWEI] traffic behavior test [HUAWEI-behavior-test] redirect ip-nexthop 100.1.1.2 2. Configure traffic classifier based on basic ACL. [HUAWEI] acl 2000 [HUAWEI-acl-basic-2000] rule 10 permit source 200.1.1.2 0 [HUAWEI-acl-basic-2000] quit [HUAWEI] traffic classifier test [HUAWEI-classifier-test] if-match acl 2000 3. Create a traffic policy and associate it with the created traffic classifier and behavior. [HUAWEI] traffic policy test [HUAWEI-trafficpolicy-test] classifier test behavior test 4. Apply the traffic policy to the inbound direction of an interface. [HUAWEI] interface GigabitEthernet 1/0/1 [HUAWEI-GigabitEthernet1/0/1] traffic-policy test inbound

Modifying the number of equal-cost OSPF routes on the USG2000&USG2000 series
Perform as follows to configure the maximum number of equal-cost OSPF routes on the USG2000 series: 1. In the user view, run the system-view command to enter the system view. 2. Run the ospf [ process-id ] command to access the OSPF process view. 3. Run the maximum load-balancing number command to configure the maximum number of equal-cost routes. A maximum of eight equal-cost OSPF routes are supported.

Maximum number of equal-cost OSPF routes supported by an S series switch
The maximum number of equal-cost OSPF routes on an S series modular switch that supports OSPF is 16 and that on an S series fixed switch that supports OSPF is 8. You can run the maximum load-balancing number command to set the maximum number of equal-cost OSPF routes.

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