You can configure route maps to filter and modify routes. This allows you to manage network communication in the cloud. Before you use the route map feature, you must add a route map first.

Background information

A transit router supports route tables and route maps within a region. You can filter routes by associating route maps with a route table of a transit router. Route maps are used to filter routes in the inbound and outbound directions. Filtered routes are advertised by transit routers in each region to network instances deployed in the same region or other regions. For more information, see Overview.

Transit routers support the Basic Edition and Enterprise Edition based on regions. A Basic Edition transit router has only a default route table. An Enterprise Edition transit router has a default route table and allows you to create custom route tables. After you create a route map, it is associated with the default route table of a Basic Edition or Enterprise Edition transit router. You cannot associate a route map with a custom route table of an Enterprise Edition transit router. For more information about how to view the Edition of the current transit router, see View the edition of a transit router.

Add a route map to an Enterprise Edition transit router

  1. Log on to the CEN console.
  2. On the Instances page, find the Cloud Enterprise Network (CEN) instance and click the instance ID.
  3. On the instance details page, find the region where you want to add a route map and click the ID of the transit router deployed in the region.
  4. On the details page of the transit router, click the Route Table tab.
  5. On the details page of the route table, click the ID of the default route table.
  6. On the details page of the default route table, click the Route Maps tab.
  7. On the Route Maps tab, click Add Route Map. Set the following parameters and click OK.
    Parameter Description
    Route Map Priority Set a priority for the route map. A lower value indicates a higher priority.

    After you specify a priority value for a route map, you cannot set the same priority value for another route map that is applied in the same region and direction. The system evaluates whether the routes meet the match conditions specified in the route map with the highest priority. Therefore, set proper priorities for route maps to meet your business requirements.

    Description Enter a description for the route map.
    Region Select the region where the route map is applied.
    Transmit Direction Select the direction in which the route map is applied.
    • Import to Regional Gateway: Routes are advertised to transit routers deployed in the current region. For example, routes are advertised from network instances deployed in the current region or other regions to the transit router deployed in the current region.
    • Export from Regional Gateway: Routes are advertised from transit routers deployed in the current region. For example, routes are advertised from transit routers deployed in the current region to network instances deployed in the current region or transit routers deployed in other regions.
    Match Conditions Select a match condition for the route map.

    You can click Add Match Condition to add multiple match conditions. For more information, see Match conditions.

    Action Policy Select an action policy.
    • Permit: After all conditions are matched, the matched routes are permitted.
      If you select Permit, you can click Add Policy Entry and select one of the following values:
      • Preference: Specify a priority value for the route that can be permitted. Valid values: 1 to 100. Default value: 50. A smaller value indicates a higher priority.
      • Community: Specify a community attribute. The additive and replace methods are supported.
      • Appended AS Path: An autonomous system (AS) path is appended when the transit router receives or advertises routes.
        The requirements of appended AS paths vary based on the direction in which the route map is applied:
        • When AS paths are appended in the inbound direction, you must specify the list of source instance IDs and the source region in the match condition. In addition, the source region must be the same as the region where the route map is applied.
        • When AS paths are appended in the outbound direction, you must specify the list of destination instance IDs in the match condition.
    • Deny: Routes that meet all the match conditions are denied.

      If you select Deny, you cannot set Associated Priority.

    Associated Priority Optional. Specify a priority value for the next associated route map. Valid values: 1 to 100.
    • If Associated Priority is not set, no next route map is associated with the current one.
    • If the value is set to 1, the current route map is associated with the next one.
    • If the value is set to a number other than 1, the value must be greater than the priority value that you set for the current route map. This means that the priority of the associated route map must be lower than that of the current one.
    Note You can set Associated Priority only if you select Permit for Action Policy. Only matched routes continue to match the route maps that are associated with priorities.

Add a route map to a Basic Edition transit router

  1. Log on to the CEN console.
  2. On the Instances page, find the CEN instance and click the instance ID.
  3. On the instance details page, find the region where you want to add a route map and click the ID of the transit router deployed in the region.
  4. On the details page of the transit router, click the Route Table tab and click Route Maps.
  5. On the Route Maps tab, click Add Route Map. Set the following parameters and click OK.
    Parameter Description
    Route Map Priority Set a priority for the route map. A lower value indicates a higher priority.

    After you specify a priority value for a route map, you cannot set the same priority value for another route map that is applied in the same region and direction. The system evaluates whether the routes meet the match conditions specified in the route map with the highest priority. Therefore, set proper priorities for route maps to meet your business requirements.

    Description Enter a description for the route map.
    Region Select the region where the route map is applied.
    Transmit Direction Select the direction in which the route map is applied.
    • Import to Regional Gateway: Routes are advertised to transit routers deployed in the current region. For example, routes are advertised from network instances deployed in the current region or other regions to the transit router deployed in the current region.
    • Export from Regional Gateway: Routes are advertised from transit routers deployed in the current region. For example, routes are advertised from transit routers deployed in the current region to network instances deployed in the current region or transit routers deployed in other regions.
    Match Conditions Select a match condition for the route map.

    You can click Add Match Condition to add multiple match conditions. For more information, see Match conditions.

    Action Policy Select an action policy.
    • Permit: After all conditions are matched, the matched routes are permitted.
      If you select Permit, you can click Add Policy Entry and select one of the following values:
      • Preference: Specify a priority value for the route that can be permitted. Valid values: 1 to 100. Default value: 50. A smaller value indicates a higher priority.
      • Community: Specify a community attribute. The additive and replace methods are supported.
      • Appended AS Path: An autonomous system (AS) path is appended when the transit router receives or advertises routes.
        The requirements of appended AS paths vary based on the direction in which the route map is applied:
        • When AS paths are appended in the inbound direction, you must specify the list of source instance IDs and the source region in the match condition. In addition, the source region must be the same as the region where the route map is applied.
        • When AS paths are appended in the outbound direction, you must specify the list of destination instance IDs in the match condition.
    • Deny: Routes that meet all the match conditions are denied.

      If you select Deny, you cannot set Associated Priority.

    Associated Priority Optional. Specify a priority value for the next associated route map. Valid values: 1 to 100.
    • If Associated Priority is not set, no next route map is associated with the current one.
    • If the value is set to 1, the current route map is associated with the next one.
    • If the value is set to a number other than 1, the value must be greater than the priority value that you set for the current route map. This means that the priority of the associated route map must be lower than that of the current one.
    Note You can set Associated Priority only if you select Permit for Action Policy. Only matched routes continue to match the route maps that are associated with priorities.