Express Connect uses the following terms to describe its components, routing protocols, and circuit types. The diagram below shows a typical topology for connecting a data center to Alibaba Cloud using Express Connect circuits.
Alibaba Cloud provides multiple Express Connect circuit solutions. For more information, see Features.
Core components
Express Connect
An Alibaba Cloud service that connects data centers to Alibaba Cloud. Express Connect establishes a private, flexible, reliable, and secure connection between a data center and a virtual private cloud (VPC).
Virtual private cloud (VPC)
A virtual network dedicated to your Alibaba Cloud account. VPCs on Alibaba Cloud are logically isolated from each other. Within a VPC, you can create and manage cloud resources such as Elastic Compute Service (ECS) instances, ApsaraDB RDS instances, and Server Load Balancer (SLB) instances.
Virtual border router (VBR)
A router deployed between customer-premises equipment (CPE) and a VPC. A VBR exchanges data between a data center and a VPC.
Transit router
A transit gateway that enables communication among network instances in the cloud.
Express Connect Router (ECR)
A service component for global hybrid clouds. ECR supports communication among global Express Connect circuits, dynamic routing networking, and unified route management.
Express Connect circuit
A circuit leased from a connectivity provider to the access points of Alibaba Cloud. Express Connect circuits carry traffic between your data center and Alibaba Cloud.
Access point
A geographical location where an Express Connect circuit connects to Alibaba Cloud. Each region has one or more access points, and each access point has two access devices. Connect your data center to a VPC through one of the access points in the nearest region.
Routing protocols and strategies
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 aggregation
A technique for connecting an access device to multiple Express Connect circuits and associating a virtual border router (VBR) with those circuits. Configure ECMP alongside link aggregation to make full use of the combined bandwidth.
Circuit types
Express Connect offers two circuit types. The right choice depends on whether you manage the physical connection yourself or work through a partner.
Dedicated Express Connect circuit
A circuit dedicated to a single customer that directly connects your data center to an Alibaba Cloud access point.
Shared Express Connect circuit
A circuit shared among multiple tenants, provisioned by an Express Connect partner. The partner's access point is already connected to Alibaba Cloud. The partner connects your data center to Alibaba Cloud and then provisions a connection for you.