ipv6 prefix-priority (IS-IS view)

Function

The ipv6 prefix-priority command sets a convergence priority for IPv6 IS-IS routes.

The undo ipv6 prefix-priority command restores the default value.

By default, in IP routing table, the priority of IS-IS host routes and default routes is high; the convergence priority of the other IS-IS routes is medium.

Format

ipv6 prefix-priority [ level-1 | level-2 ] { critical | high | medium | very-low } { ipv6-prefix prefix-name | tag tag-value }

undo ipv6 prefix-priority [ level-1 | level-2 ] { critical | high | medium | very-low }

Parameters

Parameter	Description	Value
level-1	Sets a convergence priority for Level-1 IS-IS routes.	-
level-2	Sets a convergence priority for Level-2 IS-IS routes.	-
critical	Sets the convergence priority of IS-IS routes to critical.	-
high	Sets the convergence priority of IS-IS routes to high.	-
medium	Sets the convergence priority of IS-IS routes to medium.	-
very-low	Sets the convergence priority of IS-IS routes to very-low.	-
ipv6-prefix prefix-name	Specifies the name of an IPv6 prefix list to filter routes. You can set a convergence priority for the IS-IS routes that match the specified IPv6 prefix list.	The value is a string of 1 to 169 case-sensitive characters.
tag tag-value	Specifies the tag value to filter routes. You can set a convergence priority for the IS-IS routes with the specified tag value.	The value is an integer ranging from 1 to 4294967295. There is no default value.

Views

IS-IS view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
isis	write

Usage Guidelines

Usage Scenario

When a routing table has a large number of routing entries on an IS-IS device, it takes a long time to implement the SPF calculation on the device. The ipv6 prefix-priority command can be used to allow some key routes to be preferentially calculated.

The command takes effect only on the basic IPv6 topology on the public network.

Prerequisites

If a tag value is used to filter IS-IS routes, it is required that IS-IS routes carry tag values.

Configuration Impact

The convergence priorities of IS-IS routes can be critical, high, medium, low, and very-low. The priorities in the corresponding IP routing table are critical, high, high, medium, and low. The priorities are listed in descending order.

The convergence priority of IS-IS routes is used as follows:

For the existing IS-IS routes, IS-IS sets their convergence priority based on the configuration of the ipv6 prefix-priority command.
For the newly added IS-IS routes, IS-IS sets the convergence priority for the routes based on the filtering result of the ipv6 prefix-priority command.
If an IS-IS route matches the matching rules of multiple convergence priorities, the highest convergence priority is used.
If an IS-IS route matches tags of multiple convergence priorities, the highest convergence priority is used.
If the route level is not specified, IS-IS sets a convergence priority for both Level-1 and Level-2 routes.

Precautions

The convergence priority of IS-IS routes (including the IS-IS host routes and default routes) can be specified or changed using the ipv6 prefix-priority command. After the ipv6 prefix-priority command is run, the convergence priority of the routes (including the IS-IS host routes and default routes) unspecified by the command is changed to low.

Example

# In a basic IPv6 topology, set the convergence priority of IS-IS Level-1 routes with the tag 3 to critical.

<HUAWEI> system-view
[~HUAWEI] isis 1
[*HUAWEI-isis-1] ipv6 enable
[*HUAWEI-isis-1] ipv6 prefix-priority level-1 critical tag 3