The isis link-quality low incr-cost command enables the function to adjust the link cost of an interface when its link quality is low.
The undo isis link-quality low incr-cost command disables the function.
By default, an IS-IS interface cannot adjust the link cost based on link quality.
isis link-quality low incr-cost { cost-value | max-reachable }
isis process-id process-id-value link-quality low incr-cost { cost-value | max-reachable }
undo isis link-quality low incr-cost [ { cost-value | max-reachable } ]
undo isis process-id process-id-value link-quality low incr-cost [ { cost-value | max-reachable } ]
| Parameter | Description | Value |
|---|---|---|
| cost-value |
Specifies a link cost adjustment value. After this parameter is specified:
|
The value is an integer ranging from 1 to 16777213. |
| max-reachable |
Adjusts the link cost to the maximum link cost.
|
- |
| process-id process-id-value |
Specifies the IS-IS multi-instance process ID when multi-instance is enabled under the relevant process. |
The value is an integer ranging from 1 to 4294967295. |
| low |
Indicates that the link cost of an interface is adjusted when its link quality is low. |
- |
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Usage Scenario
A bit error indicates the deviation between a bit that is sent and the bit that is received. Bit errors caused by optical fiber aging or optical signal jitter are inevitable on carrier networks. During data transmission, a high bit error rate will degrade or even interrupt services in extreme cases.
To ensure network reliability, run the isis link-quality low incr-cost command to enable the device to adjust the link cost of an IS-IS interface when its link quality is low. If the IS-IS interface detects that its link quality is low, the device increases the link cost of the interface, so that this link, which has a higher bit error rate, is not selected as the optimal link. After the link quality reverts, the device automatically restores the link cost of the IS-IS interface.Prerequisites
IS-IS has been enabled on the interface using the isis enable command.
Configuration Impact
If the isis link-quality low incr-cost command is run more than once in the same view, the latest configuration overrides the previous one.
Precautions
The configuration with the topology-name parameter has a higher priority than that without the parameter. Specifically, if both the isis link-quality low incr-cost { cost-value | max-reachable } and isis topology topology-name link-quality low incr-cost { cost-value | max-reachable } commands are run for an interface, the configuration with the topology-name parameter takes effect when the interface is in the specified topology. When the interface is another topology, the configuration without the topology-name takes effect for the interface.
<HUAWEI> system-view [~HUAWEI] isis 1 [*HUAWEI-isis-1] quit [*HUAWEI] interface GigabitEthernet0/1/0 [*HUAWEI-GigabitEthernet0/1/0] isis enable [*HUAWEI-GigabitEthernet0/1/0] isis link-quality low incr-cost max-reachable