The import-route isis level-1 into level-2 command enables IS-IS Level-1 area routes to leak to a Level-2 area.
The undo import-route isis level-1 into level-2 command disables IS-IS Level-1 area routes from leaking to a Level-2 area.
By default, all the Level-1 area routes (except default routes) can leak to a Level-2 area.
import-route isis level-1 into level-2 [ tag tag-value | filter-policy { acl-number | acl-name acl-name-value | ip-prefix ip-prefix-name | route-policy route-policy-name | route-filter xpl-policy-name } | direct allow-filter-policy | no-sid ] *
undo import-route isis level-1 into level-2
undo import-route isis level-1 into level-2 { tag tag-value | filter-policy { acl-number | acl-name acl-name-value | ip-prefix ip-prefix-name | route-policy route-policy-name | route-filter xpl-policy-name } | direct allow-filter-policy | no-sid } *
| Parameter | Description | Value |
|---|---|---|
| tag tag-value |
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-1 area routes that match the filtering policy can leak to a Level-2 area. |
- |
| acl-number |
Specifies the number of a basic ACL. Only the IS-IS Level-1 area routes that match the ACL rule can leak to a Level-2 area. |
The value is an integer ranging from 2000 to 2999. |
| acl-name acl-name-value |
Specifies the name of a named basic ACL. Only the IS-IS Level-1 area routes that match the ACL rule can leak to a Level-2 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-1 area routes that match the IP prefix list can leak to a Level-2 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-1 area routes that match the route-policy can leak to a Level-2 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 xpl-policy-name |
Specifies the name of a 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-1 area direct routes that match the filtering policy can leak to a Level-2 area. If the parameter is not configured, all Level-1 area direct routes will leak to a Level-2 area. |
- |
| no-sid |
Specifies that the SID is not imported during route import. |
- |
Usage Scenario
When multiple Level-1-2 devices in an IS-IS Level-1 area are connected to a Level-2 area, information about all the routes except the default route in the Level-1 area leak to the Level-2 area. The routes in the Level-1 area destined for one device in the Level-2 area may be forwarded by the same Level-1-2 device, causing traffic imbalance.
You can run the import-route isis level-1 into level-2 command on one Level-1-2 device to enable some Level-1 routes to leak to the Level-2 area and run the command on other Level-1-2 devices to enable the rest Level-1 routes to leak to the Level-2 area. Then, traffic that is sent from the Level-2 area and destined for different network segments in the Level-1 area will be forwarded to different Level-1-2 routers.Prerequisites
An IS-IS process has been created using the isis command.
Configuration Impact
After the undo import-route isis level-1 into level-2 command is run, the IS-IS backbone area cannot obtain the routes in the Level-1 area, causing area disconnection.
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.