Help Center/ Enterprise Router/ Best Practices/ Migrating a Network from Direct Connect to Enterprise Router/ Overview
Updated on 2024-01-16 GMT+08:00
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Overview

Scenario

Before Enterprise Router is launched, you can use Direct Connect to build a hybrid cloud network. If your on-premises data center needs to access multiple VPCs, you may need more than one Direct Connect connections to improve network reliability, which may result in the following problems:
  • Multiple connections may lead to complex networking and incur higher O&M costs.
  • Connections are independent of each other and cannot work in load balancing or active/standby mode.

To improve the reliability of your hybrid cloud network and reduce O&M costs, you can migrate the network by replacing Direct Connect with Enterprise Router.

For details, see Enterprise Router Service Overview.

Architecture

Your on-premises data center can access VPC-X in region A over a Direct Connect connection that has a virtual gateway (VGW-A) and two virtual interfaces (VIF-A01 and VIF-A02). To improve the reliability of your hybrid cloud network and reduce O&M costs, you can migrate the network by replacing Direct Connect with Enterprise Router.

This process consists of three phases: before migration, during migration, and after migration.
  1. Before the migration, virtual gateway VGW-A directly connects to VPC-X and works with virtual interfaces VIF-A01 and VIF-A02 to allow the on-premises data center to access VPC-X.
  2. During migration
    1. Attach VPC-X and virtual gateway VGW-A to an enterprise router. In the route table of VPC-X, ensure that the routes of the virtual gateway and the enterprise router do not conflict with each other. A CIDR block larger than the on-premises CIDR block will be used to avoid route conflicts.
    2. Create a virtual gateway VGW-B and attach it to the enterprise router.

      VGW-B is used to replace VGW-A after the migration.

    3. Delete virtual interface VIF-A02 associated with virtual gateway VGW-A and create virtual interface VIF-B02 for virtual gateway VGW-B.

      VIF-B02 is used to replace VIF-A02 after the migration. The on-premises data center can access VPC-X through the enterprise router.

    4. Delete virtual interface VIF-A01 associated with virtual gateway VGW-A and create virtual interface VIF-B01 for virtual gateway VGW-B.

      VIF-B01 is used to replace VIF-A01 after the migration.

  3. When the on-premises data center can access the VPC through the enterprise router, delete virtual gateway VGW-A.
Figure 1 Architecture of replacing Direct Connect with Enterprise Router

Advantages

As a high-performance central hub on the cloud, an enterprise router can connect multiple network instances. For example, if multiple VPCs and Direct Connect virtual gateways are attached to an enterprise router, the VPCs can share one Direct Connect connection to connect the on-premises data center.
  • Enterprise routers support route learning, which frees you from complex configurations and simplifies O&M.
  • Enterprise routers make it possible for multiple connections to work in load balancing or active/standby mode.

Enterprise Router and Direct Connect can work together to build a highly reliable hybrid cloud network. For details, see Allowing Direct Connect and VPN to Work in an Active and Standby Pair to Link an On-Premises Data Center to the Cloud.

Constraints

Migrating the network from Direct Connect to Enterprise Router may cause intermittent disconnections. Submit a service ticket and contact customer service to evaluate the migration solution. Here are some example scenarios that connectivity may be interrupted.
  • If resources in a service VPC have virtual IP addresses bound, the service VPC cannot be attached to an enterprise router.
  • If a service VPC is being used by ELB, VPC Endpoint, NAT Gateway (private NAT gateway), Distributed Cache Service (DCS), or hybrid DNS, this VPC cannot be attached to an enterprise router.