This topic describes the quotas and limits that apply to Internet Shared Bandwidth, including instance quotas, bandwidth limits, and EIP association requirements.
Quotas
The following table lists the default quotas for Internet Shared Bandwidth.
| Item | Default limit | Adjustable? |
|---|---|---|
| Pay-as-you-go Internet Shared Bandwidth instances per Alibaba Cloud account per region | 5 | Yes. Contact your account manager to request an increase. |
| Elastic IP addresses (EIPs) per Internet Shared Bandwidth instance | 100 | Yes. Log on to the Quota Center console to apply for an increase. For more information, see Request a quota increase. |
Bandwidth limits
Inbound and outbound bandwidth
Both inbound and outbound bandwidth are allocated up to the maximum bandwidth of the Internet Shared Bandwidth instance:
Inbound bandwidth: The system allocates bandwidth equal to the maximum bandwidth of the instance for inbound traffic.
Outbound bandwidth: The system allocates bandwidth equal to the maximum bandwidth of the instance for outbound traffic.
For example, if the maximum bandwidth of an Internet Shared Bandwidth instance is 5 Gbit/s, both inbound and outbound traffic can reach a maximum of 5 Gbit/s.
How bandwidth is distributed
An Internet Shared Bandwidth instance delivers shared bandwidth through a cluster of servers. To ensure efficient and stable data transfer, network traffic is evenly distributed across all servers in the cluster. As a result, the maximum bandwidth of a single connection is determined by the following formula:
Maximum bandwidth per connection = Maximum bandwidth of the instance / Number of servers in the clusterFor example, if the maximum bandwidth of an Internet Shared Bandwidth instance is 2,000 Mbit/s and the cluster contains four servers, the maximum bandwidth per connection is 500 Mbit/s (2,000 / 4). The instance can reach its full maximum bandwidth only when traffic is spread across multiple connections.
The maximum bandwidth is not guaranteed. It represents an upper limit for reference only. When demand exceeds available resources, the actual bandwidth may be lower than the specified value.
We recommend that you set the maximum bandwidth to a value higher than your actual bandwidth requirement when you purchase an instance. In some cases, the actual bandwidth allocated by the Internet Shared Bandwidth instance may exceed the specified maximum bandwidth. These cases will become rare as the service is upgraded. Setting a higher value helps prevent service interruptions.
If the maximum bandwidth of the Internet Shared Bandwidth instance you purchase is higher than 1 Gbit/s, the bandwidth of each server is automatically throttled.
Limits on EIPs
Before you associate EIPs with an Internet Shared Bandwidth instance, make sure that the following requirements are met:
The EIPs use the pay-as-you-go billing method.
The EIPs and the Internet Shared Bandwidth instance are in the same region.
The line type of the EIPs is the same as that of the Internet Shared Bandwidth instance.