Cloud Enterprise Network (CEN) is a highly available network built on the global private network of Alibaba Cloud. CEN supports high performance and low latency. CEN uses transit routers to establish cross-region connections between virtual private clouds (VPCs). This enables VPCs to communicate with data centers and formulates flexible, stable, and enterprise-class networks in the cloud.

How transit routers work

Components

  • CEN instances

    CEN instances are the basic resources that are used to create and manage cloud networks. Transit routers are deployed on CEN instances.

    A CEN instance can contain one or more transit routers. You can use bandwidth plans and the cross-region connection feature of transit routers to enable communication between network instances in different regions.

  • Transit routers

    Transit routers are the core network element that forwards network traffic across regions. Transit routers are region-specific and support custom routing policies. For a CEN instance, you can create only one transit router in each region.

  • Network instances
    You can use transit routers to connect the following network instances. This way, you can enable cloud resource communication, cross-region communication, and communication between cloud resources and on-premises resources.
    • Virtual private clouds (VPCs)
    • Virtual border routers (VBRs)
    • Cloud Connect Network (CCN) instances
    • Transit routers
  • Network instance connections
    A network instance connection refers to the connection between a transit router and a network instance. Network instance connections are classified into the following types:
    • VPC connection
    • VBR connection
    • CCN instance connection
    • Cross-region connections

      A cross-region connection refers to the connection between transit routers in different regions. You can purchase a bandwidth plan to enable communication between network instances in different regions. Network instances in the same region can communicate with each other through transit routers. You do not need to create cross-region connections or purchase bandwidth plans.

  • Route tables of transit routers

    Network instances that are connected through a transit router forward traffic by using the route table of the transit router. A transit router has a default route table. You can create custom route tables and configure communication, isolation, and traffic redirection policies by using the associated forwarding and route learning features.

    • Default route table

      The system automatically creates a default route table for each transit router.

    • Custom route tables

      You can manually create custom route tables. Custom route tables are similar to virtual routing and forwarding (VRF) used by traditional routers. A custom route table is isolated from the default route table and other custom route tables.

    • Associated forwarding

      You can enable associated forwarding for a network instance connection and a route table of a transit router. After you enable associated forwarding, the transit router forwards traffic based on the route table that is associated with the network instance.

    • Route learning

      You can enable route learning for a network instance connection and a route table of a transit router. After you enable route learning, the route table can automatically learn routes from the network instance.

  • Bandwidth plans

    A bandwidth plan provides bandwidth resources to enable cross-region communication. You can use bandwidth plans and the cross-region connection feature of transit routers to enable communication between network instances in different regions. For more information, see Work with bandwidth plans.

Transit router editions

Transit routers have two editions: Basic Edition and Enterprise Edition. Enterprise Edition is an upgraded version of Basic Edition and supports all features of Basic Edition. In addition, Enterprise Edition supports custom routing policies. For more information, see How transit routers work.

The following table lists the regions and zones that support Basic Edition and Enterprise Edition.

Table 1. Regions and zones that support Enterprise Edition transit routers
Area Region Zone
Chinese mainland China (Hangzhou) Zone H and Zone I
China (Shanghai) Zone F and Zone G
China (Nanjing - Local Region) Zone A
China (Shenzhen) Zone D and Zone E
China (Heyuan) Zone A and Zone B
China (Guangzhou) Zone A and Zone B
China (Qingdao) Zone B and Zone C
China (Beijing) Zone H and Zone G
China (Zhangjiakou) Zone A and Zone C
China (Hohhot) Zone A and Zone B
China (Ulanqab) Zone A and Zone B
China (Chengdu) Zone A and Zone B
Asia Pacific Singapore (Singapore) Zone B and Zone C
China (Hong Kong) Zone B and Zone C
Malaysia (Kuala Lumpur) Zone A and Zone B
India (Mumbai) Zone A and Zone B
Indonesia (Jakarta) Zone A and Zone B
Philippines (Manila) Zone A
Japan (Tokyo) Zone A and Zone B
Europe Germany (Frankfurt) Zone A and Zone B
UK (London) Zone A and Zone B
North America US (Virginia) Zone A and Zone B
US (Silicon Valley) Zone A and Zone B
Australia Australia (Sydney) Zone A and Zone B
Table 2. Regions that support Basic Edition transit routers
Area Region
Chinese mainland Chinese mainland CCN
Asia Pacific South Korea (Seoul), Japan CCN, Singapore CCN, Hong Kong CCN, Malaysia CCN, and Indonesia CCN
Europe Frankfurt CCN
Australia Australia CCN

Benefits

  • Worldwide network communication
    You can use transit routers and bandwidth plans to connect VPCs in different regions to data centers. This allows networks to communicate on a global scale. In the same region, a transit router can connect to at most 200 VPCs. This allows you to expand networks.
  • Low latency and high speed
    CEN provides low-latency and high-speed network transmission. In the same region, the data transfer rate can reach the maximum rate supported by the device port. Resources can communicate with each other on a global scale. Compared with data transmission over the Internet, network latency is greatly reduced.
  • High reliability and high quality
    Transit routers can be deployed in active/standby mode. Network traffic is automatically switched between the active and standby transit routers to ensure service availability. Multiple sets of high-quality connections exist between any two nodes in the network established by CEN. When Layer 2 connections are interrupted, the network automatically converges in case your workloads are interrupted.
  • Secure and flexible enterprise-class networking
    Transit routers support custom routing policies to meet the requirements of enterprise-class networking. For example, you can create a network topology that supports security zones, demilitarized zones, and service chaining.
  • Convenience with pay-as-you-go
    Transit routers support the pay-as-you-go billing method. For network communication within the same region, you are charged only for the connected network instances and data transfer processed by the transit routers. You can also create cross-region connections without device or ISP line deployment, and adjust connection settings as needed. This reduces networking costs.
  • One-stop O&M
    The CEN console displays your network resources in different regions. You can query intra-region and cross-region network typologies and check network status in the console. The CEN console supports visualized management that improves O&M efficiency.

Notes on network transmission

Alibaba Cloud offers a private network with high performance and low latency. This private network provides a secure cloud computing environment to meet your networking requirements. Packet loss during network transmission may be caused by many factors, such as network stream collisions, Layer 2 network errors, and other network errors. Alibaba Cloud aims to provide network services with an hourly packet loss rate of less than 0.0001% for 99% of packets.

When you use CEN, take note of the following rules:
  • Only network traffic transmitted over CEN passes through the Alibaba Cloud transmission network. CEN can minimize the packet loss rate in cross-region transmission when bandwidth resources are sufficient.
  • Express Connect circuits that connect mainland China to regions outside mainland China are provided by China Unicom. These Express Connect circuits are optimized and maintained in the same way as the Alibaba Cloud transmission network to minimize packet loss.