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Virtual Private Cloud:Prefix lists

Last Updated:Dec 02, 2024

A prefix list consists of one or more CIDR blocks. You can use prefix lists to facilitate the configuration and management of virtual private cloud (VPC) route tables and Cloud Enterprise Network (CEN) route tables. You can share prefix lists with other Alibaba Cloud accounts by using the Resource Management service.

Overview

A prefix list is a set of one or more CIDR blocks that compose a logical object. You can add frequently visited IP addresses to a prefix list and configure routes that point to the prefix list. This way, you do not need to configure routes one by one. If you need to route requests to another CIDR block, you only need to update the prefix list. Route tables that reference the prefix list are automatically updated. You can view, modify, and delete prefix lists created by you.

A prefix list consists of multiple entries. Each entry consists of a CIDR block and a description.

You can use the Resource Sharing service to share a prefix list with another Alibaba Cloud account, or folders or members in a resource directory. If you share a prefix list with an Alibaba Cloud account (principal) within the same resource directory, the invitation is automatically accepted by the principal by default. If the principal does not belong to the same resource directory, the principal must manually accept the invitation.

Billing

The prefix list feature is free of charge.

Scenarios

Limits and quotas

Limits

  • A prefix list can be used only in the region where the prefix is created.

  • Prefix lists support IPv4 and IPv6.

  • When you create a prefix list, you must specify the maximum number of entries. After you associate a prefix list with a route table, the prefix list consumes the quota of routes in the route table. For example, a VPC route table supports up to 200 custom routes. After you associate a prefix list that consists of 20 entries with the VPC route table, the VPC route table supports up to 180 custom routes.

  • You cannot associate a prefix list with a gateway route table.

  • When you create gateway endpoints for different cloud service types in a region for the first time, the system automatically creates a system prefix list. The system prefix list cannot be modified or deleted. For more information, see Gateway endpoints.

Regions that support prefix lists

The following table lists the regions that support IPv4 and IPv6 prefix lists.

Area

Region

Asia Pacific

China (Hangzhou), China (Shanghai), China (Nanjing - Local Region), China (Qingdao), China (Beijing), China (Zhangjiakou), China (Hohhot), China (Ulanqab), China (Shenzhen), China (Heyuan), China (Guangzhou), China (Chengdu), China (Hong Kong), China (Wuhan - Local Region), China (Fuzhou - Local Region), Japan (Tokyo), South Korea (Seoul), Singapore, Malaysia (Kuala Lumpur), Indonesia (Jakarta), Philippines (Manila), and Thailand (Bangkok)

Europe & Americas

Germany (Frankfurt), UK (London), US (Silicon Valley), and US (Virginia)

Middle East

UAE (Dubai) and Saudi Arabia (Riyadh)

Important

The SAU (Riyadh - Partner Region) region is operated by a partner.

Quotas

Name/ID

Description

Default value

Adjustable

vpc_quota_prefixlist_num

Maximum number of prefix lists that can be created by an Alibaba Cloud account

10

You can increase the quota by performing the following operations:

vpc_quota_prefixlist_cidr_num_per_prefixlist

Maximum number of CIDR blocks each prefix list can contain

50

vpc_quota_prefixlist_accept_shared_prefixlist_num

Maximum number of prefix lists that can be shared with each principal

100

vpc_quota_prefixlist_share_user_num_per_prefixlist

Maximum number of principals with which a prefix list can be shared

10

N/A

Maximum number of associations for each prefix list

Unlimited

N/A

For more information about resource sharing quotas, see Limits on resource sharing.

References

For more information about how to create, manage, and use prefix lists, see the following topics: