Note the following limits before you use the Express Connect service.

Item Quota Can I apply for an increase to the quota?
The maximum number of physical connections that an account can establish at an access point 2 Yes. You can apply for an increase to the quota by using the quota management function.
The maximum number of Virtual Border Routers (VBRs) that can be created in a physical connection 5 Yes. You can apply for an increase to the quota by using the quota management function.
The maximum number of idle VBRs (VBRs without interfaces) that an account supports 5 No.
The maximum number of VBRs that an account can create for other accounts 2 No.
The maximum number of route entries that can be added to a VBR 48 Yes. You can apply for an increase to the quota by using the quota management function.
The maximum number of Border Gateway Protocol (BGP) route entries that are supported by a VBR 110 Yes. You can apply for an increase to the quota by opening a ticket.
The number of BGP route entries that can be advertised on each VBR. 10 Yes. You can apply for an increase to the quota by using the quota management function.
We recommend that you use private CIDR blocks for an on-premises data center and a VPC to communicate with each other. The CIDR blocks cannot conflict with each other.
If you use two physical connections to access Alibaba Cloud, you must configure health checks so that traffic is distributed to the standby link when the active link fails.
The function of creating VBRs for other accounts is disabled by default. The owner of the physical connection and the owner of the VBR must belong to the same enterprise. If you have a physical connection under your account, you can apply to enable this function by opening a ticket.
You are not allowed to create VBRs for other accounts of a different site. For example, an account of the China site is not allowed to create VBRs for another account of the international site.

Communication limits

The communication limits between a VPC and an on-premises data center are as follows:

  • The maximum read/write speed of Object Storage Service (OSS) is 5 Gbit/s.
  • To improve the reliability, the speed of a single hash stream from a VPC to a VBR is limited to one twelfth (or one fourth, one eighth, one sixteenth) of the bandwidth that Alibaba Cloud internally specifies in the corresponding Express Connect specification. For example, if the bandwidth from the VBR to the VPC is large1, namely 1 Gbit/s, the maximum bandwidth of a single hash stream is 85 Mbit/s.

    Hash stream: the data stream that is defined by the combination of the source IP address, source port, transport layer protocol, destination IP address, and destination port. For example, 192.168.1.1 10000 TCP 121.14.88.76 80 forms a hash stream. This hash stream means that a terminal whose IP address is 192.168.1.1 is connected to port 80 of a terminal whose IP address is 121.14.88.76 through port 10000 by using the TCP protocol.

Access point limits

The limits of access points are as follows:

  • Multiple access points that reside in different locations are provided in one region. The network latency between two access points that are in the same region but two different zones is less than five milliseconds.
  • If your requirements on latency are high, you can select an access point that is closest to your cloud servers. To know the access point that is closest to your cloud servers, open a ticket.

Physical connection limits

The limits of physical connections are as follows:

  • Before you use the Express Connect service, you must allocate appropriate CIDR blocks for the connection between the VPC and on-premises data center. Make sure that the gateway of the VPC and the gateway of the on-premises data center do not overlap with each other.
  • The cloud services in VPCs use 100.64.0.0/10 as the service address. On-premises data centers connected to VPCs through Express Connect cannot use CIDR blocks that overlap with 100.64.0.0/10.
  • Alibaba Cloud provides optical modules with 1G and 10G ports free of charge, and the transmission distance is 10 km. If you need a longer transmission distance or a 40G or 100G port, you must purchase the optical module yourself.

Limits on cable installation at the data center of Alibaba Cloud

Note the following limits before you instruct the cable installation company to go to the data center of Alibaba Cloud:

  • The cable installation company must follow the construction rules stipulated by the data center provider and Alibaba Cloud engineers. If the cable installation company fails to follow the rules, it is not allowed to install cables at the data center.
  • If you purchase optical ports, make sure that the service provider connects an optical fiber to the port of Alibaba Cloud.
  • If you purchase electrical ports, make sure that the service provider connects an electrical cable to the port of Alibaba Cloud.
  • Alibaba Cloud data centers do not support the hosting of fiber optical transceivers. The cable installation company cannot install any fiber optical transceivers at data centers of Alibaba Cloud.
  • The leased line installation schedule is subject to data center lockdowns required by local authorities or Alibaba Cloud. To obtain the lockdown duration required by Alibaba Cloud, consult your customer manager.
  • The data centers where Alibaba Cloud access points are located are rent from telecom service providers. Therefore, you may be charged by the service providers for cable connections to the data center building and leased indoor cables.

Limits on redundant physical connections

The limits on redundant physical connections are as follows:

  • Alibaba Cloud only guarantees the service availability of such redundant physical connections that are connected to different access points. If multiple physical connections are connected to the same access point or only one physical connection is connected to an access point, the service availability cannot be guaranteed.
  • If you use two physical connections to connect to Alibaba Cloud, we recommend that you configure health checks so that failovers can be implemented. If you do not configure health checks, your services will be affected.

Limits on shared physical connections

If you use a shared pre-deployed leased line of an Alibaba Cloud partner to establish a physical connection, note the following limits:

  • Configurations of ports are fixed. Alibaba Cloud cannot adjust port configurations even if you have special requirements.
  • Equal-cost multi-path (ECMP) link aggregation is not supported.

Time span for leased line connection

The following table shows the time that Alibaba Cloud needs to complete the leased line connection.

Operations by Alibaba Cloud Time span
Review of the application to go to an Alibaba Cloud data center for leased line connection Two workdays
Review of the application for LOA Two workdays
Fiber pigtail installation Alibaba Cloud provides optical modules:
  • Two workdays for the installation within Mainland China
  • Three workdays for the installation outside Mainland China
    Note Four workdays are needed for access points in Japan.
The customer provides optical modules:
  • Within Mainland China: two workdays after Alibaba Cloud receives the optical module
  • Outside Mainland China: three workdays after Alibaba Cloud receives the optical module
    Note Four workdays are needed for access points in Japan.
Review of the application to go to an Alibaba Cloud data center for leased line maintenance Two workdays