Plan and create a VPC with IPAM - Virtual Private Cloud - Alibaba Cloud Documentation Center

IP Address Manager (IPAM) automates CIDR block assignment and conflict detection when you create virtual private clouds (VPCs). Without it, manually coordinating address ranges across teams and environments risks overlaps that are costly to fix after deployment.

Example

This tutorial walks through a common enterprise scenario: a company with multiple business departments that each require isolated VPCs for production and testing. You will create an IPAM pool hierarchy, then use it to allocate a CIDR block automatically when creating VPC1 in the production environment. The process takes the following steps:

Create an IPAM and a private IPAM scope.
Create a top-level pool and a sub-pool in sequence, and then provision a CIDR block.
A large CIDR block, 192.168.0.0/16, is allocated to the top-level pool. The sub-pool for the production environment is created from the top-level pool and has a CIDR block of 192.168.0.0/20.
Create VPC1 and allocate its CIDR block from the production environment address pool.

Procedure

Step 1: Create an IPAM

Log on to the IPAM console. In the top menu bar, select the region where you want to create the IPAM.
On the IPAM page, click Create IPAM and set the Effective Region. For the other parameters, you can use the default values or change them as needed.
Note
- You must specify at least one applicable region when you create an IPAM. The applicable regions must include the managed region of the IPAM.
- The managed region is the region where the IPAM is located and cannot be deleted.

Step 2: Create a top-level pool

In the navigation pane, click IPAM Pool.
On the IPAM Pool page, click Create IPAM Pool. Configure the parameters as shown in the following figure.This topic describes only the parameters that are relevant to this example. For all other parameters, use the default values. For more information, see Create and manage IPAM pools.
- IPAM Scope: Select a private IPAM scope.
- CIDR Range: Select IPAM to create a top-level pool.
- Effective Region: The region of the IPAM pool. The region must be supported by the IPAM. This setting cannot be changed after the pool is created.
- Automatically Import Discovered Resource: If this feature is enabled, IPAM continuously discovers VPCs and automatically imports resources whose CIDR blocks are within the scope of the IPAM pool and are not already allocated.
- Provision CIDR Block: Click Add CIDR Block to add one or more IPv4 CIDR blocks.
- Allocation Rule: You can set the Minimum Mask Length, Default Mask Length, and Maximum Mask Length for resources allocated from the pool.

Step 3: Create a sub-pool

Configure the parameters as shown in the following figure. The sub-pool, with a CIDR block of 192.168.0.0/20 provisioned from the top-level pool, is used for the production environment.

This topic describes only the parameters that are relevant to this example. For parameters not listed, use the default values. For more information about the parameters, see Create and manage IPAM pools.

IPAM Scope: Only private IPAM scopes can be selected.
CIDR Range: You can select IPAM Pool. This creates a sub-pool of the source pool.
Source IPAM Pool: Select the top-level pool created in Step 2.
Effective Region: If an applicable region is set for the source IPAM pool, you do not need to set one for the sub-pool because it inherits the region from its source pool.
Automatically Import Discovered Resource: When enabled, IPAM continuously discovers VPCs and automatically imports unallocated resources whose CIDR blocks are within the pool's range.
Provision CIDR Block: Click Add CIDR Block to add one or more IPv4 CIDR blocks.
Allocation Rule: You can set the Minimum Mask Length, Default Mask Length, and Maximum Mask Length for resources allocated from the pool.

After the sub-pool is created, the pool hierarchy is shown in the following figure.

Step 4: Create VPC1 and a vSwitch, and allocate a CIDR block from the IPAM pool

Log on to the VPC console.
In the top menu bar, select the region for the VPC. In this example, select the Same region as the IPAM pool.
On the VPC page, click Create VPC. Set the following parameters for the VPC and vSwitch, and then click OK.
This topic describes only the parameters that are relevant to this example. For parameters not listed, use the default values. For more information about the parameters, see Create and manage a VPC.
- IPv4 CIDR: Select Allocated by IPAM.
- Select Pool: Select the pool that you created in Step 3.
- Network Mask: After you specify the network mask, the system allocates the first available CIDR block that matches the specified mask range by default. Alternatively, you can specify an IPv4 CIDR block from the provisioned CIDR blocks of the pool.
- IPv4 CIDR for the vSwitch: This must be a sub-block of the IPv4 CIDR block allocated by IPAM.
After the address pool is created, the Details tab shows that 1.6% of the address resources in the pool have been allocated, as described in Step 3.
Note
The provisioned CIDR block for the sub-pool is 192.168.0.0/20, which provides 4,096 available IP addresses. The network mask is specified as /26, which means 64 IP addresses from the pool are allocated to VPC1. Therefore, 64/4096 = 1.6% of the address resources in the pool are allocated to the VPC.
On the Allocation tab, you can view the address resources that are allocated to the VPC.

References

For more information about the features, scenarios, limits, and billing of IPAM, see IP Address Manager (IPAM).
For more information about how to use IPAM for efficient, scalable, and secure network address planning, see Address planning.