This topic describes how to migrate a VPC 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, please make sure:
  • You have registered an Alibaba Cloud account. If you don't have an account, please register. For more information, visit Account Registration.
  • The overlapping routing function is enabled for the CEN instance. If not, plase enable. For more information, see Enable overlapping routing.

Step 1: Attach the VPC in the peering connection to a CEN

To attach the VPC 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 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

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, check the routes. Make sure that the routes do not conflict with each other after you add the VPC to the CEN instance.

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.conflict

In the preceding figure, the CEN route 172.16.1.0/24 is more detailed than the route 172.16.0.0/16 configured for the peering connection, which constitutes a route conflict. The CEN route 172.16.1.0/24 is used as an example to illustrate how to divide a large route segment into smaller route segments.

  1. Log on to the VPC console.
  2. In the left-side navigation pane, click Route tables.
  3. On Route tables page, find the route table to which the target peering connection route belongs, and then click Manage in the Actions column.
  4. In the Route Entry List, click Add Route Entry. Add two route entries that are respectively destined for 172.16.1.0/25 and 172.16.1.128/25 with the Express Connect route interface as the next hop type.
    divide2
  5. After adding the route entries, find the target peering connection route 172.16.0.0/16 in the VPC route table and click Delete to delete this route with the Express Connect route interface as the next hop type.
    delete2
  6. Click Refresh to check if the status of the CEN route is changed to Available.
    check2
  7. After the CEN route takes effect, delete the added two route entries 172.16.1.0/25 and 172.16.1.128/25 to complete the smooth migration.