The import-route isis level-2 into level-1 command enables IS-IS routes to leak from a Level-2 area to a Level-1 area.
The undo import-route isis level-2 into level-1 command disables IS-IS route leaking from a Level-2 area to a Level-1 area.
By default, IS-IS route leaking is disabled from a Level-2 area to a Level-1 area.
import-route isis level-2 into level-1 [ tag tag | filter-policy { acl-number | acl-name acl-name | ip-prefix ip-prefix-name | route-policy route-policy-name | route-filter route-filter-name } | direct { allow-filter-policy | allow-up-down-bit } * ] *
undo import-route isis level-2 into level-1
| Parameter | Description | Value |
|---|---|---|
| tag tag |
Specifies the administrative tag assigned to the imported routes. |
The value is an integer ranging from 1 to 4294967295. |
| filter-policy |
Indicates a filtering policy to filter imported routes. Only the IS-IS Level-2 area routes that match the filtering policy can leak to a Level-1 area. |
- |
| acl-number |
Specifies the number of a basic ACL. Only the IS-IS Level-2 area routes that match the ACL rule can leak to a Level-1 area. |
The value is an integer ranging from 2000 to 2999. |
| acl-name acl-name |
Specifies the name of a named basic ACL. Only the IS-IS Level-2 area routes that match the ACL rule can leak to a Level-1 area. |
The value is a string of 1 to 64 case-sensitive characters without spaces. The value must start with a letter (a to z or A to Z, case sensitive). |
| ip-prefix ip-prefix-name |
Specifies the name of an IP prefix list. Only the IS-IS Level-2 area routes that match the IP prefix list can leak to a Level-1 area. |
The name is a string of 1 to 169 case-sensitive characters, with spaces not supported. When double quotation marks are used around the string, spaces are allowed in the string. |
| route-policy route-policy-name |
Specifies the name of a route-policy. Only the IS-IS Level-2 area routes that match the route-policy can leak to a Level-1 area. |
The name is a string of 1 to 200 case-sensitive characters, with spaces not supported. When double quotation marks are used around the string, spaces are allowed in the string. |
| route-filter route-filter-name |
Specifies the name of route filter policy. The policy is used to filter the imported routes so that only some of the routes of other routing domains can be imported. |
The value is a string of 1 to 200 case-sensitive characters, spaces not supported. If parameters are included in the referenced route-filter, specify values for them in the format of (var1, var2, ...var8) behind the route-filter name. A maximum of eight parameters can be specified, and each value ranges from 1 to 200 characters. |
| direct |
Imports direct routes. |
- |
| allow-filter-policy |
Indicates a filtering policy to filter the direct routes. If the parameter is configured, only the IS-IS Level-2 area direct routes that match the filtering policy can leak to a Level-1 area. If the parameter is not configured, all Level-2 area direct routes will leak to a Level-1 area. |
- |
| allow-up-down-bit |
Sets the Up/Down bit to 1 for the leaked direct routes. If direct allow-up-down-bit is specified, the direct routes that have already leaked to a Level-1 area cannot leak back. |
- |
Usage Scenario
When multiple Level-1-2 routers in an Level-1 area are connected to a Level-2 area, Level-1 routers are unable to know the network topology of the Level-2 area because they cannot learn the Level-2 routes. As a result, Routers in the Level-1 area forward traffic to the nearest Level-1-2 router, and sub-optimal routes may be generated.
To address this problem, you can run the import-route isis level-2 into level-1 command to enable IS-IS route leaking from a Level-2 area to a Level-1 area to help Level-1 routers select the optimal route for traffic forwarding. The import-route isis level-2 into level-1 command can be run only on Level-1-2 routers to enable IS-IS route leaking of all or some of the Level-2 routes to the Level-1 area.Prerequisites
An IS-IS process has been created using the isis command.
Configuration Impact
The imported Level-2 routes will increase the number of entries in Level-1 routing tables.
Precautions
In the route-policy specified in this command, if-match clauses can be configured to set matching rules, but apply clauses cannot be configured to set route attributes.
<HUAWEI> system-view [~HUAWEI] acl 2000 [*HUAWEI-acl4-basic-2000] quit [*HUAWEI] ip topology red [*HUAWEI] isis 1 [*HUAWEI-isis-1] cost-style wide [*HUAWEI-isis-1] topology red topology-id 10 [*HUAWEI-isis-1-topology-red] import-route isis level-2 into level-1 filter-policy 2000