isis ipv6 cost

Function

The isis ipv6 cost command sets the link cost value of an IS-IS interface in an IPv6 topology.

The undo isis ipv6 cost command restores the default link cost value of an IS-IS interface in an IPv6 topology.

By default, the link cost value of an IS-IS interface in an IPv6 topology is 10.

Format

isis ipv6 cost { cost | maximum } [ level-1 | level-2 ]

undo isis ipv6 cost [ cost | maximum ] [ level-1 | level-2 ]

Parameters

Parameter	Description	Value
cost	Specifies the IPv6 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. To set the cost style, use the cost-style command.
maximum	Sets the link cost value of an interface to 16777215. NOTE: This parameter can be configured only when the IS-IS cost style is wide or wide-compatible. When the link cost value of an interface is set to 16777215, the neighbor TLV generated on the link cannot be used for route calculation and can only be used to transmit TE information.	-
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 a large-scale IPv6 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 ipv6 cost command to set IPv6 link costs for interfaces so that traffic can be transmitted over different physical links.

Prerequisites

IS-IS has been enabled on a specified interface using the isis ipv6 enable [ process-id ] command in the interface view.

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.

The priority of the ipv6 circuit-cost command is lower than that of the isis ipv6 cost command.

If the IPv6 topology type is compatible or standard, the IPv6 and IPv4 link costs are the same on an interface even though the IPv6 link cost set using the isis ipv6 cost command is different from the IPv4 link cost. The IPv6 link cost set using the isis ipv6 cost command takes effect only when the IPv6 topology type is compatible enable-mt-spf or ipv6.

The IPv6 topology type can be set for an IS-IS process using the ipv6 enable(IS-IS) command.

Example

# Set the IPv6 link cost of VLANIF 10 to 50.

<HUAWEI> system-view

[HUAWEI] ipv6

[HUAWEI] isis

[HUAWEI-isis-1] ipv6 enable

[HUAWEI-isis-1] quit

[HUAWEI] interface vlanif 10

[HUAWEI-Vlanif10] ipv6 enable

[HUAWEI-Vlanif10] isis ipv6 enable

[HUAWEI-Vlanif10] isis ipv6 cost 50

# Set the IPv6 link cost of GE0/0/1 to 50.

<HUAWEI> system-view
[HUAWEI] ipv6
[HUAWEI] isis
[HUAWEI-isis-1] ipv6 enable
[HUAWEI-isis-1] quit
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] undo portswitch
[HUAWEI-GigabitEthernet0/0/1] ipv6 enable
[HUAWEI-GigabitEthernet0/0/1] isis ipv6 enable
[HUAWEI-GigabitEthernet0/0/1] isis ipv6 cost 50