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Express Connect:ECR

Last Updated:May 28, 2024

An Express Connect router (ECR) is a service component that forwards network traffic in the global hybrid cloud in which networks are connected over Express Connect circuits. An ECR provides features such as dynamic routing-based networking and centralized management for route advertisements. For example, you can associate virtual border routers (VBRs) and virtual private clouds (VPCs) or transit routers (TRs) with an ECR to establish connections between your data centers and cloud resources.

Feature description

  • An ECR allows you to create multi-point connections between VBRs and VPCs. This reduces the complexity associated with the original method of configuring point-to-point connections between each VBR and its corresponding VPC.

  • An ECR provides dynamic routing-based networking to connect VBRs and VPCs. You do not need to add static routes to create VBR-to-VPC connections.

  • An ECR allows you to fine-tune route advertisements by selectively advertising only the necessary CIDR blocks across the global network. This resolves the issue of having to advertise the entire route table.

  • An ECR simplifies cross-region network connections around the world and supports the pay-by-data-transfer billing method.

  • An ECR schedules the optimal forwarding route to effectively reduce network latency over Express Connect circuits.

Scenarios

Finance

Alibaba Cloud recognizes the critical need for low-latency networks in securities and quantitative trading. To address this, Alibaba Cloud provides a custom network connectivity solution that enables direct traffic forwarding by using ECRs to connect VBRs and VPCs. This solution ensures that the optimal forwarding route is used for data transfer without detours. This significantly reduces latency and provides low-latency capabilities that surpass those of other cloud networking offerings. In addition, this solution achieves the lowest forwarding latency by forwarding on-premises and cloud traffic in the same zone. This further improves network performance.

Data computing

An ECR delivers Tbit/s-level bandwidth to enable rapid data reception and transfer worldwide. This meets your requirements for ultra-high transmission bandwidth in big data computing and online or offline business operations. Stable and efficient connections are created over Express Connect circuits to support extensive data computing and fast data transmission. This meets your stringent requirements for data computing and transmission.

Multi-cloud connectivity

An ECR facilitates network transmission across multiple cloud platforms by using Express Connect circuits. This ensures the high reliability of your business deployed in multi-cloud environments. An ECR provides route aggregation and advertisement features to address the limits on the number of routes that a cloud platform can receive, and simplify route management. This helps you manage and advertise aggregated routes around the world in an efficient manner. This also allows you to build and maintain an efficient and reliable multi-cloud network architecture by simplifying O&M.

Global enterprise

The ECR feature provides an efficient and cost-optimized solution to meet your requirements for connecting global data centers. You can use flexible pay-as-you-go services that are provided by the ECR feature to help reduce the costs of global network connectivity.

E-commerce and gaming

The ECR feature provides an efficient hybrid cloud connectivity solution to meet your requirements for deploying goods warehouses in multiple regions and managing the operation of multi-category projects in the cloud. An ECR supports seamless multi-point connections between on-premises and cloud resources worldwide. This reduces the complexity of hybrid cloud networking management. You can use ECRs to build and maintain a highly reliable hybrid cloud network with ease to ensure your business continuity.

Data transfer outside China

An ECR supports nearby forwarding based on your business requirements regardless of whether your data centers are deployed in the Chinese mainland or outside China. You can use an ECR to connect scattered cloud resources to establish a global network. This way, your data centers can communicate with VPCs around the world.

Networking and procedure

Use an ECR to connect network instances.

  • You can use an ECR to directly connect VBRs and VPCs.

  • You can associate TRs with an ECR to use the advanced features of TRs for traffic over Express Connect circuits.

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Procedure

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Billing

The outbound data transfer fees in a region are calculated based on the billing of Express Connect. Cloud Data Transfer (CDT) is used to calculate cross-region or cross-border traffic fees based on the pay-by-data-transfer billing method. You are charged both the inbound and outbound data transfer fees for cross-region or cross-border connections. For more information, see Billing overview.

Note

You are charged cross-region traffic fees based on the ECRs that you create. Cost allocation is not supported.

Differences between an ECR and a TR

Both an ECR and a TR are core components used to forward network traffic.

  • An ECR forwards network traffic over Express Connect circuits at the aggregation layer in hybrid cloud networking to allow communication between your data centers and cloud resources.

  • A TR forwards network traffic at the core layer of a cloud data center to allow communication between network instances in the cloud data center.

The following figure shows how an ECR and a TR work.

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The following table compares the features of ECRs and TRs.

Feature

ECR

TR

VPC-to-VPC connections in the cloud

Not supported

Supported

Hybrid cloud connectivity

Supported

Not supported

Nearby forwarding

Supported

Not supported

Large bandwidth of 100 Gbit/s or more

Supported

Not supported

Route prefix

Supported

Not supported

Border Gateway Protocol (BGP) dynamic routing

Supported

Supported

Static routing

Not supported

Supported

Multicast communication

Not supported

Supported

Flow log management

Not supported

Supported

Limits

Feature limits

  • The cloud resources such as VPCs or TRs that are associated with an ECR cannot communicate with each other. An ECR allows connections only between VBRs and the cloud resources.

  • You cannot associate the same VPC or VBR with multiple ECRs.

  • An ECR supports only BGP dynamic routing and does not support static routing.

  • The CIDR blocks of the vSwitches in the VPCs that are associated with an ECR cannot overlap with each other.

  • The autonomous system number (ASN) of each ECR within your account must be unique. After an ECR is created, you cannot change the ASN of the ECR.

  • If the local ASN of a VBR is different from the ASN of an ECR, the VBR cannot be associated with the ECR.

  • If route prefixes are specified for a VBR, the VBR cannot be associated with an ECR. To associate the VBR with an ECR, remove the route prefixes from the VBR.

Quota limits

Item

Description

Limit

Adjustable

ecr_tr_count_per_ecr

The maximum number of TRs that can be associated with an ECR.

3

Yes

ecr_vpc_count_per_ecr

The maximum number of VPCs that can be associated with an ECR.

30

ecr_vbr_count_per_ecr

The maximum number of VBRs that can be associated with an ECR.

50

No

ecr_count_per_user

The maximum number of ECRs that can be created within each Alibaba Cloud account.

20

Yes

ecr_allowed_prefix_count_per_association

The maximum number of CIDR blocks of an associated VPC or TR that an ECR can advertise to a data center.

20

ecr_quota_max_route_entries_num

The maximum number of routes that each ECR can receive.

2,000

ec_quota_bgp_group_max_route_entry_num

The maximum number of BGP CIDR blocks that each VBR can advertise to an ECR.

110

Yes

Note

To increase the quota, contact your account manager.

tr_quota_per_ecr_num

The maximum number of ECRs with which a TR can be associated.

20

No

ecr_bandwidth_cross_region_domestic

The maximum bandwidth that an ECR supports for each cross-region connection in the Chinese mainland based on the pay-by-data-transfer billing method.

CDT sets the following protective bandwidth limits on cross-region or cross-border connections based on the regions between which the connections are created:

  • 1,000 Mbit/s: for connections that are created between regions in the Chinese mainland

  • 100 Mbit/s: for connections that are created between regions in the Chinese mainland and outside China

  • 100 Mbit/s: for connections that are created between regions outside China

Note

If you want to create multiple connections, the data transfer fees are multiplied by N based on the single-connection data transfer fees. N indicates the number of connections, which is generally four.

ecr_bandwidth_cross_border

The maximum bandwidth that an ECR supports for each cross-border connection based on the pay-by-data-transfer billing method.

ecr_bandwidth_cross_region_overseas

The maximum bandwidth that an ECR supports for each cross-region connection outside China based on the pay-by-data-transfer billing method.