Configuring IS-IS link cost
The IS-IS cost of an interface is determined in the following order:
IS-IS cost specified in interface view.
IS-IS cost specified in system view.
The cost is applied to the interfaces associated with the IS-IS process.
Automatically calculated cost.
If the cost style is wide or wide-compatible, IS-IS automatically calculates the cost using the formula: Interface cost = (Bandwidth reference value / Expected interface bandwidth) × 10, in the range of 1 to 16777214. For other cost styles, Table 6 applies.
Configure the expected bandwidth of an interface with the bandwidth command. For more information, see Interface Command Reference.
Table 6: Automatic cost calculation scheme for cost styles other than wide and wide-compatible
If none of the above costs is used, a default cost of 10 applies.
Interface bandwidth | Interface cost |
|---|---|
≤ 10 Mbps | 60 |
≤ 100 Mbps | 50 |
≤ 155 Mbps | 40 |
≤ 622 Mbps | 30 |
≤ 2500 Mbps | 20 |
> 2500 Mbps | 10 |
Configuring an IS-IS cost for an interface
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter IS-IS view. | isis [ process-id ] [ vpn-instance vpn-instance-name ] | N/A |
3. (Optional.) Specify an IS-IS cost style. | cost-style { narrow | wide | wide-compatible | { compatible | narrow-compatible } [ relax-spf-limit ] } | By default, the IS-IS cost type is narrow. |
4. Return to system view. | quit | N/A |
5. Enter interface view. | interface interface-type interface-number | N/A |
6. (Optional.) Specify a cost for the IS-IS interface. | isis cost value [ level-1 | level-2 ] | By default, no cost for the interface is specified. |
Configuring a global IS-IS cost
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter IS-IS view. | isis [ process-id ] [ vpn-instance vpn-instance-name ] | N/A |
3. (Optional.) Specify an IS-IS cost style. | cost-style { narrow | wide | wide-compatible | { compatible | narrow-compatible } [ relax-spf-limit ] } | By default, the IS-IS cost style is narrow. |
4. Specify a global IS-IS cost. | circuit-cost value [ level-1 | level-2 ] | By default, no global cost is specified. |
Enabling automatic IS-IS cost calculation
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter IS-IS view. | isis [ process-id ] [ vpn-instance vpn-instance-name ] | N/A |
3. Specify an IS-IS cost style. | cost-style { wide | wide-compatible } | By default, the IS-IS cost is narrow. |
4. Enable automatic IS-IS cost calculation. | auto-cost enable | By default, automatic IS-IS cost calculation is disabled. |
5. (Optional.) Configure a bandwidth reference value for automatic IS-IS cost calculation. | bandwidth-reference value | The default setting is 100 Mbps. |