To allow services that are deployed in different regions to communicate with each other, you must create inter-region connections and allocate bandwidth resources to the connections. This topic describes how to create an inter-region connection.
Background information

Inter-region connections support multiple bandwidth allocation modes. The bandwidth allocation modes supported by Basic Edition transit routers and Enterprise Edition transit routers are different. The following table describes the differences.
indicates that the bandwidth allocation mode is supported by the transit router.
indicates that the bandwidth allocation mode is not supported by the transit router.
Bandwidth allocation mode | Description | Basic Edition transit router | Enterprise Edition transit router |
Allocate bandwidth from bandwidth plans | You must purchase a bandwidth plan and associate it with your Cloud Enterprise Network (CEN) instance if you want to allocate bandwidth from a bandwidth plan to inter-region connections. When you create inter-region connections, bandwidth is allocated from the bandwidth plan. For more information, see Purchase a bandwidth plan. | ![]() | ![]() |
Pay-by-data-transfer | You are charged for data transfer. You can set a bandwidth cap for inter-region connections. For more information, see Cross-region data transfers. Note After you create a pay-by-data-transfer inter-region connection, you can run the | ![]() | ![]() |
Use testing bandwidth | CEN provides a testing bandwidth value of 1 Kbit/s that is free of charge for you to test the network connectivity of inter-region connections. The testing bandwidth is limited to 1 Kbit/s, and you can use it only for connectivity tests. It does not support service traffic. After you attach a network instance to a Basic Edition transit router, you can test the connectivity of inter-region IPv4 networks without creating inter-region connections. By default, the testing bandwidth is used. | ![]() | ![]() |
Limits
When you allocate bandwidth from a bandwidth plan, make sure that the sum of maximum bandwidth values specified for inter-region connections does not exceed the maximum bandwidth value of the bandwidth plan.
For example, a CEN instance is associated with a 20 Mbit/s bandwidth plan that connects the Chinese mainland to North America. You can allocate bandwidth from the bandwidth plan to inter-region connections between US (Silicon Valley) and China (Hangzhou), between US (Silicon Valley) and China (Shanghai), and between US (Silicon Valley) and China (Shenzhen). In this case, the sum of the maximum bandwidth values of the inter-region connections cannot exceed 20 Mbit/s.
Upper bandwidth limits for inter-region connections that use the Pay-As-You-Go allocation mode:
Within the Chinese mainland: 1,000 Mbit/s.
Between the Chinese mainland and regions outside the Chinese mainland: 100 Mbit/s.
If you require a higher bandwidth value, go to the Quotas page in the CEN console or to the Quota Center console to request a quota increase. For more information, see Manage CEN quotas.
Use an Enterprise Edition transit router to create an inter-region connection
- Log on to the CEN console.
- On the Instances page, click the ID of the CEN instance that you want to manage.
Navigate to the transit router to which the inter-region connection belongs, and then click Create Connection in the Actions column. tab, find the
NoteIf no transit router exists in the region where the inter-region connection is created, create a transit router in the region first. For more information, see Create a transit router.
On the Connection with Peer Network Instance page, set the parameters and click OK.
Parameter
Description
Network Type
Select Inter-region Connection.
Region
Select one of the regions to be connected.
Transit Router
Select the transit router in the region.
Attachment Name
Enter a name for the inter-region connection.
Peer Region
Select the other region to be connected.
ImportantIf you want to create an inter-border connection, you must comply with the inter-border network communication requirements. Read the requirements and select I have read and agree to the compliance requirements.
Transit Router
Select the transit router in the region.
If no transit router is available in the selected region, the system automatically creates a transit router.
Bandwidth Allocation Mode
Select the method that is used to allocate bandwidth to the inter-region connection.
Transit routers support the following bandwidth allocation modes:
Allocate from Bandwidth Plan: The bandwidth is allocated from a bandwidth plan.
Pay-By-Data-Transfer: You are charged for data transfer over the inter-region connection.
NoteThe first time Pay-By-Data-Transfer is used, you must activate the Cloud Data Transfer (CDT) service in the Note message.
CDT for inter-border network communication
CDT for intra-border network communication
Bandwidth Plan
Select a bandwidth plan that is associated with the CEN instance.
If you set Bandwidth Allocation Mode to Allocate from Bandwidth Plan, you must select a bandwidth plan.
Bandwidth
Specify a maximum bandwidth value for the inter-region connection. Unit: Mbit/s.
If you select Allocate from Bandwidth Plan, the specified bandwidth value is used as the maximum bandwidth value of the inter-region connection.
If you select Pay-By-Data-Transfer, the specified bandwidth value is used as the bandwidth cap of the inter-region connection. If the bandwidth cap is reached, bandwidth throttling is triggered.
Advanced Settings
When you create an inter-region connection, the system automatically selects the following features in the advanced settings:
Associate with Default Route Table of Transit Router
After this feature is enabled, the inter-region connection is automatically associated with the default route table of the transit router. The transit router uses the default route table to forward network traffic across regions.
Propagate System Routes to Default Route Table of Transit Router
After this feature is enabled, the inter-region connection advertises system routes to the default route table of the transit router.
Automatically Advertise Routes to Peer Region
After this feature is enabled, the routes of the transit router deployed in the current region are automatically advertised to the route table of the peer transit router. The routes are used for cross-region communication between network instances.
You can disable the preceding advanced features by clearing the check boxes. If you want to enable the VPC to communicate with other network instances, you can configure associated forwarding and route learning on the transit router. For more information, see Manage routes.
Use a Basic Edition transit router to create an inter-region connection
- Log on to the CEN console.
- On the Instances page, click the ID of the CEN instance that you want to manage.
Navigate to the transit router to which the inter-region connection belongs, and then click Create Connection in the Actions column. tab, find the
NoteIf no transit router exists in the region where the inter-region connection is created, create a transit router in the region first. For more information, see Create a transit router.
On the Connection with Peer Network Instance page, set the parameters and click OK.
Parameter
Description
Network Type
Select Inter-region Connection.
Region
Select one of the regions to be connected.
Transit Router
Select the transit router in the region.
Peer Region
Select the other region to be connected.
Transit Router
Select the transit router in the region.
If no transit router is available in the selected region, the system automatically creates a transit router.
Bandwidth Plan
Select the bandwidth plan that is associated with the CEN instance.
Bandwidth
Specify a maximum bandwidth value for the inter-region connection. Unit: Mbit/s.
Modify the bandwidth allocation method for an inter-region connection
This method is supported only by Enterprise Edition transit routers.
If you want to switch the bandwidth allocation mode from pay-by-data-transfer to a bandwidth plan, you must associate the CEN instance with a bandwidth plan. For more information, see Purchase a bandwidth plan.
If you want to switch the bandwidth allocation mode from a bandwidth plan to pay-by-data-transfer, the default maximum bandwidth value supported by the pay-by-data-transfer allocation mode must not be smaller than the current maximum bandwidth value. You can increase the default maximum bandwidth of inter-region connections supported by the pay-by-data-transfer allocation mode in the CEN console. For more information, see Manage CEN quotas.
Assume that the maximum bandwidth value of the inter-region connection between the US (Silicon Valley) and US (Virginia) regions is 101 Mbit/s, and the bandwidth is allocated from a bandwidth plan. Before you switch the bandwidth allocation mode to pay-by-data-transfer, you must first increase the default maximum bandwidth value supported by the pay-by-data-transfer mode to a value that is equal to or greater than 101 Mbit/s. For inter-region connections between regions inside the Chinese mainland, or between the Chinese mainland and regions outside the Chinese mainland, the default maximum bandwidth value supported by the pay-by-data-transfer mode is 100 Mbit/s.
- Log on to the CEN console.
- On the Instances page, click the ID of the CEN instance that you want to manage.
Navigate to the transit router to which the inter-region connection belongs. tab and click the
On the details page of the transit router, click the Cross-region Connections tab.
On the Cross-region Connections tab, find the inter-region connection that you want to manage and click Modify in the Bandwidth Allocation Mode column.
You can change the bandwidth allocation mode as described in the following scenarios:
Switch from pay-as-you-go to a bandwidth plan
In the Change Bandwidth Allocation Mode dialog box, select Switch to Allocate from Bandwidth Plan, select the bandwidth plan that you want to use, specify a maximum bandwidth value for the inter-region connection, and then click OK.
Switch from a bandwidth plan to pay-as-you-go
In the Change Bandwidth Allocation Mode dialog box, select Switch to Pay-By-Data-Transfer and click OK.
Modify the maximum bandwidth value of inter-region connections
After you create an inter-region connection, you can modify the bandwidth value for the inter-region connection based on your business requirements.
- Log on to the CEN console.
- On the Instances page, click the ID of the CEN instance that you want to manage.
Navigate to the transit router to which the inter-region connection belongs. tab and click the
On the details page of the transit router, click the Cross-region Connections tab.
On the Cross-region Connections tab, find the inter-region connection that you want to manage, and click Modify in the Bandwidth column.
In the Set Region Connection dialog box, specify a maximum bandwidth value and click OK.
The sum of the maximum bandwidth values of all inter-region connections cannot exceed the maximum bandwidth value of the bandwidth plan.
If you want to reduce the maximum bandwidth value, confirm the note in the Set Bandwidth for Inter-region Connection message and click OK.
Associate an inter-region connection with a different transit router route table
After you create an inter-region connection, you can change the transit router route table that is associated with the inter-region connection.
This method is supported only by Enterprise Edition transit routers.
If route synchronization is enabled for the inter-region connection, routes that are advertised to the peer transit router are automatically withdrawn after the route table is changed. Then, routes in the new route table are synchronized to the route table of the peer transit router. For more information, see Route synchronization.
- Log on to the CEN console.
- On the Instances page, click the ID of the CEN instance that you want to manage.
Navigate to the tab and click the transit router that you want to manage.
Click the Cross-region Connections tab, click the ID of the inter-region connection that you want to manage.
In the Attachment Details panel, find the Basic Information section, and click Modify on the right side of Associated Route Table.
In the Modify Route Table dialog box, select a transit router route table and click OK.
Delete an inter-region connection
If your service no longer requires inter-region network communication, you can delete the inter-region connections.
- Log on to the CEN console.
- On the Instances page, click the ID of the CEN instance that you want to manage.
Navigate to the transit router to which the inter-region connection belongs, and then click the ID of the transit router. tab, find the
Enterprise Edition transit router
The following procedure shows how to delete an inter-region connection from an Enterprise Edition transit router:
WarningYou can delete the inter-region connections and all relevant configurations at the same time. To prevent adverse impacts on your workloads, we recommend that you check and confirm every configuration item before you delete the configurations.
If the inter-region connection is created between a Basic Edition transit router and an Enterprise Edition transit router, delete the inter-region connection from the Enterprise Edition transit router.
On the transit router page, click the Cross-region Connections tab.
On the Cross-region Connections tab, find the inter-region connection that you want to delete and click Delete in the Actions column.
In the dialog box that appears, check and confirm the configurations, select Confirm that the deletion of the configurations does not compromise your service stability and can be deleted at the same time, and then click OK.
In the Are you sure that you want to delete the instance? message, check the configurations and click OK.
Basic Edition transit router
The following procedure shows how to delete an inter-region connection from a Basic Edition transit router:
On the transit router page, click the Cross-region Connections tab.
On the Cross-region Connections tab, find the inter-region connection that you want to delete and click Delete in the Actions column.
In the Delete Region Connection message, click OK.
References
CreateTransitRouterPeerAttachment: creates an inter-region connection on an Enterprise Edition transit router.
UpdateTransitRouterPeerAttachmentAttribute: modifies 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: configures, modifies, or deletes the inter-region bandwidth for a Basic Edition transit router.
DescribeCenInterRegionBandwidthLimits: queries the bandwidth values for inter-region connections among different regions.