Add and manage routes

Background

• After you create a VBR, you must add routes pointing to an Express Connect circuit and a Virtual Private Cloud (VPC) to forward traffic between the VPC and your on-premises data center.

• When you access an Object Storage Service (OSS) internal domain name by using Cloud Enterprise Network (CEN), Express Connect, Smart Access Gateway (SAG), or a VPN Gateway, you must configure routes for the address blocks in the corresponding region. Otherwise, network connectivity issues may occur. For more information, see Regions and endpoints.

• A VBR supports three types of routes: custom, Border Gateway Protocol (BGP), and CEN.

  • You can add and delete custom routes. Each VBR supports up to 48 custom routes.

  • A VBR supports BGP routing for your on-premises data center. For more information, see Configure and manage BGP.

  • After a VBR is attached to a CEN instance, CEN automatically synchronizes routes for the VBR.

• The VBR does not support source-based policy routing. If you need specific ECS instances to access on-premises networks over a specific Express Connect circuit, use the CEN Policy-based routing feature instead.

Add a custom route

1. Log on to the Express Connect console.

2. In the top navigation bar, select a region. In the navigation pane on the left, click Virtual Border Routers (VBRs).

3. On the Virtual Border Routers (VBRs) page, click the ID of the target VBR instance.

4. Click the Routes tab, and then click Add Route.

5. In the Add Route panel, configure the route and click OK.

   Parameter	Description
   Network Type	The network type for the route. IPv4 Routing: an IPv4 route. IPv6 Routing: an IPv6 route. Note This parameter is required only if the VBR instance supports IPv6. If you set Network Type to IPv6 Routing, the destination can be any IPv6 CIDR block except for 2403:28c0:200::/40.
   Next Hop Type	The type of next hop. VPC: forwards traffic destined for the specified CIDR block to the selected VPC. Physical Connection Interfaces: forwards traffic destined for the specified CIDR block to the selected Express Connect interface. Note If the VBR instance is attached to an Enterprise Edition transit router and you want to configure a static route from the VBR to the transit router, go to the Network Instance Route Table tab of the transit router, select the VBR instance as the network instance, and then click Add Route Entry to add the static route. For more information, see Add a route.
   Destination CIDR Block	Enter the destination CIDR block. If the error message "The CIDR format is invalid" is reported, check the format of the CIDR block. To reach a single IP address, set the destination CIDR block to a /32 mask, for example, 10.0.0.61/32. If you use a subnet mask such as /30, you must enter a valid network address, for example, 10.0.0.60/30. Do not enter a host IP address combined with a subnet mask, for example, 10.0.0.61/30, which is an invalid format.
   Next Hop	The instance to use as the next hop.
   Description	A description for the route.

Delete a custom route

1. Log on to the Express Connect console.

2. In the top navigation bar, select a region. In the navigation pane on the left, click Virtual Border Routers (VBRs).

3. On the Virtual Border Routers (VBRs) page, click the ID of the target VBR instance.

4. Click the Routes tab, find the target route, and then click Delete in the Actions column.

5. In the dialog box that appears, click OK.

FAQ

Why am I unable to connect even though routes are configured on the VBR or VPC?

• Bidirectional routing principle: Network connectivity requires routes in both directions. Even if you need to access the peer network in only one direction, configure a route to the peer CIDR block in both the source-side and destination-side route tables, including the VPC route table and the VBR route table. This ensures that return traffic is forwarded correctly.

• Route learning and synchronization: If the VBR is attached to Cloud Enterprise Network (CEN), make sure that both Auto Propagate to Default Route Table of Transit Router and Auto Publish Route to VBR are enabled. Otherwise, the VPC route table may not learn the required routes. If you use an Enterprise Edition transit router, you can also manually add a static route from the VBR to the transit router.

• Security group and ACL rules: In addition to checking the routes, verify that the ECS security groups, ACL policies of the VBR, or VPN gateway policies allow the relevant source and destination CIDR blocks and ports (for example, port 2222 or 18080). Even with correct routes, connectivity may fail if traffic is blocked by a security policy.

API reference

• CreateRouteEntry: Creates a custom route in a route table.

• ModifyRouteEntry: Modifies the name and description of a custom route.

• DescribeRouteEntryList: Lists the routes for a VBR. Before you delete a custom route, call this operation to retrieve the route's NextHopId.

• DeleteRouteEntry: Deletes a custom route from the route table of a VBR.