Central Networks

Scenarios

After an enterprise router is created, you can create a central network and add the enterprise router to a policy of the central network. In this way, resources can communicate with each other across regions, and network resources in each region can be managed centrally.

If both global DC gateways and enterprise routers are added to a central network, the on-premises data centers can access the cloud.

Constraints

• Before building a central network, you need to create enterprise routers and enable Default Route Table Association and Default Route Table Propagation for them.
  Figure 1 Enabling Default Route Table Association and Default Route Table Propagation for enterprise routers
  
• To enable communication between on-premises data centers and the cloud, you need to create global DC gateways and add them to the central network as attachments.
  

  You can check the regions where global DC gateways are available on the Direct Connect console.

Creating a Central Network

1. Go to the Central Networks page.
2. In the upper right corner of the page, click Create Central Network.
3. Configure the central network by referring to Table 1.

   Table 1 Parameters for creating a central network

   Parameter	Setting	Example Value
   Basic Information
   Name	Enter a name for the central network.	gcn-test
   Description (Optional)	Describe the central network for easy identification.	-
   Add Enterprise Router	Add an enterprise router to enable VPCs in the same region to communicate with each other. By working with global DC gateways provided by Direct Connect, enterprise routers enable the VPCs and on-premises data centers to communicate with each other. Enterprise routers in different regions can be connected over a central network to allow for cross-region communication between VPCs and between on-premises data centers and VPCs. Click Add Enterprise Router and select the region and route table. Before using the central network, you need to add enterprise routers. Only one enterprise router can be added for a region. All added enterprise routers can communicate with each other by default. 10 kbit/s of free bandwidth is provided for testing the connectivity between enterprise routers. If no enterprise router is available for your services, click Create Enterprise Router to create one.	ER-01 ER-02
   Advanced Settings
   Full-Mesh Peering	This function is enabled by default. Expand the advanced settings to see the full-mesh peering connection list.	-
   Full-Mesh Peering Connections	If this option is enabled, a peering connection will be automatically created between every two enterprise routers you select. All these peering connections will be displayed in the full-mesh peering connection list. You can remove unnecessary peering connections as needed. Removing a peering connection: Click To be removed in the Operation column of the target peering connection. Connecting a peering connection: Click Peering Connection in the Operation column of the target peering connection. A numerical value that is used to identify a peering connection on an enterprise router. For full-mesh peering connections, the value can only be 0.	-
   Enterprise router peering connection	The connections to enterprise routers are not free. The price of connections on a central network is determined by the number of pay-per-use enterprise routers.	-

4. Click Buy Now. Check the central network configuration, read and select the Cloud Connect Service Disclaimer, and click Submit.

Follow-up Operations

• Add attachments.

  For details, see Managing Central Network Attachments.

• Assign cross-site connection bandwidths.

  For details, see Cross-Site Connection Bandwidths.