Overview

Central Network

Relying on the cloud backbone network, a central network allows you to easily set up a reliable, intelligent enterprise-grade network and manage global network resources on premises and on the cloud. By setting up a central network, you can enable communication between enterprise routers, as well as between enterprise routers and your on-premises data center, in the same region or different regions.

Application Scenarios

Cross-region communication on the cloud: Enterprise routers in different regions are added to a central network as attachments so that resources in these regions can communicate with each other over one network.
Figure 1 Cross-region communication between enterprise routers
Communication between on-premises data centers and the cloud: Enterprise routers and global DC gateways are added to a central network as attachments. In this way, multiple VPCs on the cloud can communicate with on-premises data centers across regions.
Figure 2 Communication between enterprise routers and on-premises data centers
Global network: By flexibly changing the central network policies, you can build a global network more conveniently.

Central Network Quotas

**Table 1** Central network quotas
Quota Type	Default Quota	Adjustable
Central networks in an account	6	Yes .
Policies for a central network	500	Yes .
Policy document size (KB)	10	No
Enterprise routers on a central network as attachments in a region	1	No
Global DC gateways on a central network as attachments in a region	3	Yes .

Constraints on Central Networks

To use a central network, the following resources must have been created:
- Enterprise router: used to build a central network
Policy management
- A central network can only have one policy. If you apply another policy for this central network, the policy that was previously applied will be automatically cancelled.
- In each policy, only one enterprise router can be added for a region. All added enterprise routers can communicate with each other by default.
- A policy that is being applied or cancelled cannot be deleted.
Cross-site connection bandwidth management
- A cross-site connection bandwidth cannot be changed or deleted when it is being created, updated, deleted, frozen, unfrozen, or is recovering.
- The total of cross-site connection bandwidths cannot exceed the global connection bandwidth.
- If a cross-site connection bandwidth is deleted, you will still be billed for the global connection bandwidth.