Inter-region connections

Background information

Bandwidth allocation modes

Inter-region connections support multiple bandwidth allocation modes. Supported modes differ between Basic Edition and Enterprise Edition transit routers.

Note

The icon indicates the mode is supported. The icon indicates the mode is not supported.

Bandwidth allocation mode	Basic edition	Enterprise edition	Description	Use cases	Supported line types
allocate from bandwidth plan			Purchase a bandwidth plan and associate it with your CEN instance. Bandwidth is allocated from this plan when creating the inter-region connection. This mode incurs bandwidth plan fees. Billing.	Ideal for long-running services with stable peak traffic, such as file transfers, data migration, and data synchronization.	Gold
pay-by-data-transfer			You are charged for actual data transferred. You can set a bandwidth limit to prevent excessive usage. This mode incurs data transfer fees, billed by Cloud Data Transfer (CDT). Cross-region data transfers in Cloud Data Transfer. Note After creating a pay-by-data-transfer inter-region connection, use the `ping` command to test connectivity. If you `ping` with packets smaller than 100 bytes per second from the source to the peer region, the data transfer fee is less than CNY 0.01 and is waived by Alibaba Cloud.	Ideal for large, frequent, and unpredictable traffic patterns, such as temporary scaling, testing, video conferencing, and real-time gaming.	Platinum Gold For existing Pay-By-Data-Transfer inter-region connections, the default line type is Gold. You can change the line type.
Use testing bandwidth			CEN provides 1 Kbps of free inter-region bandwidth for connectivity tests only, not for service testing or normal communication. With Basic Edition transit routers, you can test inter-region IPv4 connectivity without creating an inter-region connection. The system uses testing bandwidth by default.	For testing inter-region network connectivity only. This mode does not support service traffic.	Gold

Line types

Line types determine the service quality for data transmission.

Limitations

When using a bandwidth plan, the total bandwidth of all associated inter-region connections cannot exceed the plan's bandwidth.

For example, if a bandwidth plan provides 20 Mbps between the Chinese mainland and North America, you can distribute it across connections from US (Silicon Valley) to China (Hangzhou), China (Shanghai), and China (Shenzhen). The total bandwidth of these connections cannot exceed 20 Mbps.
For inter-region connections that use the Pay-By-Data-Transfer bandwidth allocation mode, the default maximum inter-region bandwidth limits are as follows:
- 1,000 Mbps for connections between regions in the Chinese mainland.
- 100 Mbps for connections between a region in the Chinese mainland and a region outside the Chinese mainland, and for connections between regions outside the Chinese mainland.
To increase these limits, request a quota increase on the CEN Quota Management page or in Alibaba Cloud Quota Center. Increase CEN-related quotas.

Prerequisites

A transit router is created in each region you intend to connect. Create a transit router instance.
To use the Allocate From Bandwidth Plan mode, purchase a bandwidth plan first. Use a bandwidth plan.

Create an inter-region connection

Enterprise edition transit router

Log on to the CEN console.
On the CEN Instance page, click the ID of the CEN instance that you want to manage.
On the Basic Settings > Transit Router tab, find the transit router in one of the regions you want to connect, and click Create Connection in the Actions column.

On the Connection with Peer Network Instance page, configure the parameters for the inter-region connection and click OK.

Parameter	Description
Network Type	Select Inter-region Connection.
Region	Select one of the regions to connect.
Transit Router	Automatically displays the transit router ID in the selected region.
Attachment Name	Enter a name for the inter-region connection.
Peer Region	Select the peer region to connect. Important For cross-border connections, comply with applicable requirements and follow the instructions in the console.
Transit Router	Automatically displays the transit router ID in the peer region.
Tag	Add a tag to the inter-region connection. Tag key: cannot be an empty string. The key can be up to 64 characters in length and cannot start with `aliyun` or `acs:`. It cannot contain `http://` or `https://`. Tag value: can be an empty string. The value can be up to 128 characters in length and cannot start with `aliyun` or `acs:`. It cannot contain `http://` or `https://`. You can add multiple tags. Tags.
Bandwidth Allocation Mode	Select a bandwidth allocation mode. Enterprise Edition transit routers support: Allocate From Bandwidth Plan: Allocate bandwidth from a purchased bandwidth plan. Pay-By-Data-Transfer: You are charged based on the actual data transferred over the inter-region connection. Data transfer fees in this mode are billed by CDT.
Bandwidth Plan	Select a bandwidth plan that is associated with the CEN instance. This parameter is required if you select the Allocate From Bandwidth Plan mode.
Bandwidth	Set the bandwidth for the inter-region connection, in Mbps. If you select Allocate From Bandwidth Plan, this parameter specifies the peak bandwidth for the connection. If you select Pay-By-Data-Transfer, this parameter specifies the bandwidth limit for the connection. The default bandwidth for connections between regions in the Chinese mainland is 1,000 Mbps. The default bandwidth is 100 Mbps for connections between a region in the Chinese mainland and a region outside the Chinese mainland, and for connections between two regions outside the Chinese mainland.
Default Line Type	Select a line type for the inter-region connection. If you select the Allocate From Bandwidth Plan mode, only the Gold line type is supported. If you select the Pay-By-Data-Transfer mode, both the Platinum and Gold line types are supported.
Advanced Settings	The following advanced features are enabled by default: Associate with Default Route Table of Transit Router Associates the inter-region connection with the default route tables of the transit routers in both regions. Inter-region traffic is forwarded based on these default route tables. Propagate system routes to transit router route table Establishes a route learning relationship between the inter-region connection and the default route tables of the transit routers in both regions. Automatically Advertise Routes to Peer Region Advertises routes from the local transit router's route table to the peer transit router's route table, enabling inter-region connectivity for network instances. You can clear these options and customize connectivity later using route association and route learning. Route management.

After creation, view and manage the connection on the Inter-Region Connections tab of the Enterprise Edition transit router details page.

If cross-region communication fails, troubleshoot with Use the reachability analyzer or Diagnose a transit router instance.

Basic edition transit router

Log on to the CEN console.
On the CEN Instance page, click the ID of the CEN instance that you want to manage.
On the Basic Settings > Transit Router tab, find the transit router in the connection's region, and click Create Connection in the Actions column.

On the Connection with Peer Network Instance page, configure the parameters for the inter-region connection and click OK.

Parameter	Description
Network Type	Select Inter-region Connection.
Region	Select one of the regions to connect.
Transit Router	Automatically displays the transit router ID in the selected region.
Peer Region	Select the peer region to connect.
Transit Router	Automatically displays the transit router ID in the peer region.
Bandwidth Plan	Select a bandwidth plan that is associated with the CEN instance.
Bandwidth	Set the bandwidth for the inter-region connection, in Mbps.

After creation, view and manage the connection on the Inter-Region Connections tab of the Basic Edition transit router details page.

After the inter-region connection is created, its status is Available.

If cross-region communication fails, troubleshoot with Use the reachability analyzer.

Manage inter-region connections

Monitor inter-region connection

Monitor bandwidth usage and create threshold-based alert rules to prevent service disruptions from resource exhaustion. Monitor an inter-region connection.
View the communication latency of an inter-region connection on an Enterprise Edition transit router for both Platinum and Gold line types in the NIS console.
- Compare latency across line types: View inter-region network performance.
- Change the line type: Modify the line type of an inter-region connection.

Change bandwidth allocation mode

Changing the bandwidth allocation mode does not affect your network. This operation is supported only for Enterprise Edition transit routers; not for connections between two Basic Edition transit routers.
To switch from pay-by-data-transfer to allocate from bandwidth plan, ensure the CEN instance is associated with a bandwidth plan. Purchase a bandwidth plan.
To switch from allocate from bandwidth plan to pay-by-data-transfer, ensure the default peak bandwidth of the pay-by-data-transfer mode is greater than or equal to the current peak bandwidth. You can increase it in the console. Increase CEN-related quotas.

For example, assume that an inter-region connection between US (Silicon Valley) and US (Virginia) has a peak bandwidth of 101 Mbps and uses the allocate from bandwidth plan mode. Before you change the mode to pay-by-data-transfer, you must first increase the default peak bandwidth for the pay-by-data-transfer mode to at least 101 Mbps. The default peak bandwidth is 100 Mbps for connections between a region in the Chinese mainland and a region outside the Chinese mainland, and for connections between two regions outside the Chinese mainland.

Log on to the CEN console.
On the CEN Instance page, click the ID of the CEN instance that you want to manage.
On the Basic Settings > Transit Router tab, find the transit router in the connection's region and click its ID.
On the details page of the transit router, click the Inter-Region Connections tab.
On the Inter-Region Connections tab, find the connection that you want to manage. In the Bandwidth Allocation Mode column, click Modify.
The next step depends on the current bandwidth allocation mode:
- Switch from pay-by-data-transfer to allocate from bandwidth plan
  
  In the Change Bandwidth Allocation Mode dialog box, select Switch to Allocate from Bandwidth Plan, select a bandwidth plan to associate with the connection, specify a peak bandwidth, and then click OK.
- Switch from allocate from bandwidth plan to pay-by-data-transfer
  
  In the Change Bandwidth Allocation Mode dialog box, select Switch to Pay-By-Data-Transfer, and then click OK.

Change connection bandwidth

Adjust the bandwidth of an inter-region connection after creation.

Log on to the CEN console.
On the CEN Instance page, click the ID of the CEN instance that you want to manage.
On the Basic Settings > Transit Router tab, find the transit router in the connection's region and click its ID.
On the details page of the transit router, click the Inter-Region Connections tab.
On the Inter-Region Connections tab, find the connection that you want to manage. In the Bandwidth column, click Modify.
In the Set Inter-region Bandwidth dialog box, adjust the bandwidth value and click OK.
- If the connection uses the allocate from bandwidth plan mode, the bandwidth value cannot exceed the available bandwidth of the bandwidth plan. You can upgrade the bandwidth plan to increase its available bandwidth.
- If the connection uses the pay-by-data-transfer mode, the bandwidth value cannot exceed the available bandwidth. Increase it by adjusting the quota. Increase CEN-related quotas.
If you are reducing the peak bandwidth, review the risk warning in the Set Bandwidth for Inter-region Connection dialog box and click OK.

Change line type

You can change the line type for inter-region connections that use the Pay-By-Data-Transfer mode, but only if both ends of the connection are Enterprise Edition transit routers. Connections involving a Basic Edition transit router default to the Gold line type and cannot be changed.

Log on to the CEN console.
On the CEN Instance page, click the ID of the CEN instance that you want to manage.
On the Basic Settings > Transit Router tab, find the transit router in the connection's region and click its ID.
On the details page of the transit router, click the Inter-Region Connections tab.
On the Inter-Region Connections tab, find the connection that you want to manage. In the Default Line Type column, click Modify.
In the Modify Default Line Type dialog box, select a new line type and click OK.

Before changing the line type, compare latency in the NIS console. View inter-region network performance.

Modify associated route table

Change the transit router route table associated with an inter-region connection after creation.

Warning

This operation is supported only by Enterprise Edition transit routers.
If route synchronization is enabled for the inter-region connection, changing the associated route table causes the system to withdraw previously synchronized routes and synchronize routes from the new table to the peer. The peer route table is the one that has a route learning relationship with the inter-region connection. Route synchronization.

Log on to the CEN console.
On the CEN Instance page, click the ID of the CEN instance that you want to manage.
On the Basic Settings > Transit Router tab, click the ID of the transit router in the target region.
Click the Inter-Region Connections tab, find the target inter-region connection, and click its ID.
In the Attachment Details pane, in the Basic Information section, click Modify next to Associate with Route Table.
In the Modify Route Table dialog box, select the target route table and click OK.

Delete inter-region connection

Delete an inter-region connection when you no longer need cross-region communication.

Log on to the CEN console.
On the CEN Instance page, click the ID of the CEN instance that you want to manage.
On the Basic Settings > Transit Router tab, find the transit router instance in the region of the inter-region connection, and click the transit router instance ID.
Enterprise Edition transit router

For Enterprise Edition transit routers:
Warning
- You can delete an inter-region connection and its associated configurations simultaneously. Verify each configuration before deletion to prevent service disruptions.
- If an inter-region connection is between an Enterprise Edition transit router and a Basic Edition transit router, you must delete the connection from the Enterprise Edition transit router side.
1. On the details page of the transit router, click the Inter-Region Connections tab.
2. On the Inter-Region Connections tab, find the connection that you want to delete. In the Actions column, click Delete.
3. In the delete dialog box, review each associated configuration for each region. After you confirm that deleting the configurations does not affect your service stability, select the confirmation checkbox at the bottom of the dialog box, and then click OK.
4. In the Are you sure that you want to delete the instance? dialog box, confirm the action and click OK.
Basic Edition transit router

For Basic Edition transit routers:
1. On the details page of the transit router, click the Inter-Region Connections tab.
2. On the Inter-Region Connections tab, find the connection that you want to delete. In the Actions column, click Delete.
3. In the Delete Region Connection dialog box, click OK.

API reference

Use tools such as the Alibaba Cloud SDK, Alibaba Cloud CLI, Terraform, and Resource Orchestration Service (ROS) to call the following API operations:

CreateTransitRouterPeerAttachment: Creates an inter-region connection for an Enterprise Edition transit router.
UpdateTransitRouterPeerAttachmentAttribute: Modifies the configurations of an inter-region connection on an Enterprise Edition transit router.
ListTransitRouterPeerAttachments: Queries the inter-region connections on an Enterprise Edition transit router.
DeleteTransitRouterPeerAttachment: Deletes an inter-region connection from an Enterprise Edition transit router.
SetCenInterRegionBandwidthLimit: Sets, modifies, or deletes an inter-region bandwidth limit for a Basic Edition transit router.
DescribeCenInterRegionBandwidthLimits: Queries the bandwidth limits of inter-region connections.