Usage Scenario
You can configure a link cost for interfaces or run the auto-cost enable command to enable automatic interface cost calculation.
Prerequisites
No interface cost has been set in the interface view, and no global cost has been configured in the IS-IS view.
Configuration Impact
After automatic interface cost calculation is enabled, the system automatically calculates the interface cost.
If the cost style of the system is wide or wide-compatible:
When
auto-cost enable command is configured, Interface cost = (Bandwidth-reference/Interface bandwidth) * 10.
When
auto-cost enable compatible command is configured, Interface cost = (Bandwidth-reference/Interface bandwidth).
When the cost type is narrow, narrow-compatible, or compatible, the cost of each interface is determined as follows:
- Interface bandwidth ≤ 10 Mbit/s, cost = 60
- 10 Mbit/s < interface bandwidth ≤ 100 Mbit/s, cost = 50
- 10 Mbit/s < interface bandwidth ≤ 155 Mbit/s, cost = 40
- 155 Mbit/s < interface bandwidth ≤ 622 Mbit/s, Cost = 30
- 622 Mbit/s < Interface bandwidth ≤ 2.5 Gbit/s, cost = 20
- 2.5 Gbit/s < interface bandwidth, Cost = 10
Precautions
The auto-cost enable command cannot change the cost of a loopback interface.
The
auto-cost enable command can be run on Eth-Trunk interfaces as well as on physical interfaces. If the command is run on an Eth-Trunk interface, the bandwidth of the Eth-Trunk interface is equal to the total bandwidth of all its member interfaces.
If the command is run in the IS-IS view, it takes effect only in the base topology. If the command is run in the IS-IS topology view, it takes effect only in the current topology.