This topic describes the terms commonly used in Express Connect.

The following figure shows a network topology for using Express Connect circuits to connect data centers to Alibaba Cloud.

Note Alibaba Cloud provides multiple Express Connect circuit solutions. For more information, see Functions and features.

The following table describes terms used in Express Connect.

Express ConnectAn Alibaba Cloud service that connects data centers to Alibaba Cloud. By using Express Connect, you can establish a private, flexible, reliable, and secure connection between a data center and a VPC.
Virtual Private Cloud (VPC)A virtual network dedicated to your Alibaba Cloud account. VPCs on Alibaba Cloud are logically isolated from each other. You can create and manage your cloud resources, such as Elastic Compute Service (ECS) instances, ApsaraDB RDS instances, and Server Load Balancer (SLB) instances, that are deployed in VPCs.
virtual border router (VBR)A router deployed between the customer-premises equipment (CPE) and a VPC. A VBR is used to exchange data between a data center and a VPC.
vRouterA network hub that connects vSwitches in a VPC and serves as a gateway to connect VPCs to other networks.
Cloud Enterprise Network (CEN)A networking service that lets you connect VPCs or connect VPCs and data centers. It features automatic route distribution and learning, fast network convergence, and high-quality and secure cross-network communication. CEN allows you to connect all your network resources to build a network with enterprise-class communication capabilities.

CEN eliminates the need to configure inter-VPC routes, which simplifies network operations and maintenance. For more information, see What is CEN?.

Express Connect circuitA circuit leased from a connectivity provider to the access points of Alibaba Cloud.
access pointA geographical location where an Express Connect circuit is connected to Alibaba Cloud. Two access devices are deployed in each access point. One or more access points are deployed in each region. You can connect your data center to a VPC by using one of the access points.
Border Gateway Protocol (BGP)A standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems or over the Internet.
equal-cost multi-path (ECMP)A routing strategy where packet forwarding to a single destination can occur over multiple optimal paths with equal cost.
link aggregationYou can connect an access device to multiple Express Connect circuits, associate a VBR with the Express Connect circuits, and configure ECMP to make full use of the bandwidth of the connections.
dedicated Express Connect circuitA circuit that is dedicated to you. It connects your data center to an Alibaba Cloud access point.
shared Express Connect circuitA circuit shared by you and other tenants. The access point of an Express Connect partner is already connected to an access point of Alibaba Cloud. After the partner connects to your data center and Alibaba Cloud, the partner then provisions a connection for you.