isis cost

Function

The isis cost command sets the link cost value of an IS-IS interface.

The undo isis cost command restores the default link cost value of an IS-IS interface.

By default, the link cost value of an IS-IS interface is 10.

Format

isis cost { cost | maximum } [ level-1 | level-2 ]

undo isis cost [ cost | maximum ] [ level-1 | level-2 ]

Parameters

Parameter	Description	Value
cost	Specifies the link cost value of an interface.	The value is an integer that varies according to the cost style. When the cost style is narrow, narrow-compatible, or compatible, the value ranges from 1 to 63. When the cost style is wide or wide-compatible, the value ranges from 1 to 16777214. The default value is 10.
maximum	Sets the link cost of IS-IS interfaces to 16777215. NOTE: You can configure this parameter only when the IS-IS cost style is wide or wide-compatible. After the interface cost is set to 16777215, the neighbor TLV generated on the link can only be used to transmit TE information but cannot be used for route calculation.	-
level-1	Specifies the link cost value of a Level-1 interface. If the interface level is not specified, link cost values of Level-1 and Level-2 interfaces are set.	-
level-2	Specifies the link cost value of a Level-2 interface. If the interface level is not specified, link cost values of Level-1 and Level-2 interfaces are set.	-

Views

Interface view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

On large networks, there may be multiple valid routes to the same destination. IS-IS uses the SPF algorithm to calculate an optimal route and transmits traffic over it, which brings the following problems:

All traffic is transmitted over the optimal route, causing load imbalance.
If the optimal route is faulty, traffic will get lost.

To solve the preceding problems, run the isis cost command to set a link cost for interfaces so that traffic can be transmitted over different physical links.

Prerequisites

IS-IS has been enabled on the interface using the isis enable command.

Configuration Impact

If the link cost of an interface is changed, routes will be re-calculated on the whole network, causing the changes in traffic forwarding paths.

Precautions

The priority of the circuit-cost command is lower than that of the isis cost command.

Example

# Set the Level-2 link cost of VLANIF100 to 5.

<HUAWEI> system-view
[HUAWEI] isis
[HUAWEI-isis-1] network-entity 01.0000.0000.0001.00
[HUAWEI-isis-1] quit
[HUAWEI] interface vlanif 100
[HUAWEI-Vlanif100] isis enable 1
[HUAWEI-Vlanif100] isis cost 5 level-2

# Set the Level-2 link cost of GE0/0/1 to 5.

<HUAWEI> system-view
[HUAWEI] isis
[HUAWEI-isis-1] network-entity 01.0000.0000.0001.00
[HUAWEI-isis-1] quit
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] undo portswitch
[HUAWEI-GigabitEthernet0/0/1] isis enable 1
[HUAWEI-GigabitEthernet0/0/1] isis cost 5 level-2