This topic describes how to migrate a Virtual Border Router (VBR) that uses a peering connection to a Cloud Enterprise Network (CEN) instance. By using CEN, you can build private network communication channels between VPCs or between VPCs and on-premises data centers. CEN uses automatic route distribution and learning, which can improve the network convergence and the quality and security of cross-network communication, and achieve the interconnection of all network resources.

Prerequisites

Before you start, make sure the following conditions are met:
  • You have registered an Alibaba Cloud account. If you don't have an account, visit Account Registration to register for Alibaba Cloud account.
  • The overlapping routing function is enabled for the CEN instance. If not, enable the feature first. For more information, see Enable overlapping routing.
  • If you have enabled health check for the VBR, delete the health check configurations.

Step 1: Attach a VBR in a peering connection to a CEN

To attach a VBR in a peering connection to a CEN instance, follow these steps.

  1. Log on to the CEN console.
  2. On the Instances page, find the target CEN instance, and then click Manage in the Actions column.
  3. On the Networks tab, click Attach Network and add the VBR and VPC to be migrated.
    For more information, see Attach networks.
  4. Optional: If you need the VPC to communicate with other resources that belong to different regions, you need to buy a bandwidth package and set an intranet communication bandwidth value.
  5. Optional: If you have added routes destined for ECS instances, VPN Gateways, or High-Availability Virtual IP Addresses (HaVips) in the VPC, you need to publish these routes to the CEN instance.
    route publish
  6. Optional: If an on-premises data center needs to access cloud resources, such as OSS and PrivateZone, configure through the CEN console.
    For more information, see Configure PrivateZone access.

Step 2: View routes

To check CEN routes information, follow these steps.

  1. Log on to the CEN console.
  2. On the Instances page, find the target CEN instance, and then click Manage in the Actions column.
  3. Click on the Routes tab and check the routes. Make sure that the routes do not conflict with each other.

Step 3: Divide routes and exercise CEN routes learning

The static route configured for the peering connection takes precedence over the dynamic route of the CEN instance. Specifically, if a static route is configured for the peering connection, no CEN route that is more detailed than or the same as the static route is allowed to be learnt by the CEN instance. If route conflicts exist, we recommend that you divide a large route segment into smaller route segments and delete these routes after CEN learns the routes to ensure smooth migration. conflict2

In the preceding figure, the CEN route 192.168.1.0/24 is more detailed than the route 192.168.0.0/16 configured for the peering connection, which constitutes a route conflict. The CEN route 192.168.1.0/24 is used as an example to illustrate how to divide a large route segment into smaller route segments.

  1. Log on to the Express Connect console.
  2. In the left-side navigation pane, click Virtual Border Routers (VBRs) > Virtual Border Routers (VBRs).
  3. On the Virtual Border Routers (VBRs) page, find the target VBR, click the VBR instance ID.
  4. Click Routes tab, then click Add Route to add two routes that are respectively destined for 192.168.1.0/25 and 192.168.1.128/25 with the VPC as the next hop type.
  5. For BGP routing, you need to advertise the CIDR blocks related to 192.168.1.0/25 and 192.168.1.128/25.
  6. After adding the route entries, find the target route 192.168.0.0/16 in the VBR route table and click Delete to delete this route with the VPC as the next hop type.
  7. Click Refresh to check if the status of the CEN route is changed to Available.
  8. Delete the two routes 192.168.1.0/25 and 192.168.1.128/25 in the VBR route table, and delete the advertised BGP routes.
  9. In the CEN console, configure health checks for the migrated VBR. For more information, see Configure the health check function.