A CIDR block conflict can prevent you from creating an office network or provisioning the required number of cloud computers. Plan your CIDR blocks before creating an office network — the VPC CIDR block cannot be changed after creation, so size it with room for future growth.
An office network was formerly known as a workspace. A basic office network corresponds to a basic workspace, and an advanced office network corresponds to a standard workspace.
When to plan a CIDR block
Plan your CIDR blocks in advance in the following scenarios:
AD office network: When you create an Active Directory (AD) office network, you must attach the office network and your AD to a Cloud Enterprise Network (CEN) instance. Plan the CIDR block to prevent conflicts between the office network virtual private cloud (VPC) and the CEN instance.
Alibaba Cloud VPC connection: When you access a cloud computer over Alibaba Cloud VPC using Express Connect circuit, Smart Access Gateway (SAG), or VPN Gateway, plan the CIDR block to prevent conflicts between the office network and your on-premises network.
Internal network connection: When cloud computers need to communicate with resources such as Elastic Compute Service (ECS) instances, you must create a CEN instance to enable mutual access. Plan the CIDR blocks for the ECS instance VPC, the office network, and the transit router.
Plan the office network VPC CIDR block
The office network VPC defines the network space for your cloud computers. Its CIDR block cannot be changed after creation, so size it with room for future growth before you create the office network.
Choose one of the following private CIDR blocks:
| CIDR block | Valid subnet mask |
|---|---|
| 10.0.0.0 | 12–24 |
| 172.16.0.0 | 12–24 |
| 192.168.0.0 | 16–24 |
The available CIDR blocks may vary. The CIDR blocks displayed in the Elastic Desktop Service console are authoritative.
Example: VPC CIDR block assignment
The following table shows an example configuration for connecting an on-premises data center to an office network VPC over Express Connect circuit using a Virtual Border Router (VBR).
| Item | CIDR block |
|---|---|
| Office network VPC | 192.168.0.0/16 |
| On-premises data center network | 172.30.0.0/24 |
| VBR peer IP address (VPC side) | 10.0.0.1/30 |
| VBR peer IP address (data center side) | 10.0.0.2/30 |
| Subnet mask | 255.255.255.252 |
Size the CIDR block for cloud computer capacity
Each cloud computer in an office network is automatically assigned one private IP address from the VPC CIDR block. Because one cloud computer requires one IP address, and some addresses are reserved for routing and high availability when cloud computers are deployed across zones, choose a CIDR block that provides at least twice the number of IP addresses as the cloud computers you need.
Keep the following rules in mind:
Subnet mask prefix and IP capacity: The larger the prefix (for example, /24 is larger than /16), the fewer IP addresses are available. A smaller prefix gives you more IP addresses and supports more cloud computers.
Capacity buffer: The Elastic Desktop Service console shows the theoretical maximum number of available private IP addresses. Because some addresses are reserved for routing and high availability, choose a CIDR block that provides at least twice the number of IP addresses you need.
Reserved CIDR blocks: Do not use the following CIDR blocks as the CIDR block of an office network VPC:
100.64.0.0/10,127.0.0.0/8,169.254.0.0/16,198.18.0.0/15.
Example: Sizing a CIDR block for 190 cloud computers
The following example illustrates the planning process. The configurations displayed in the Elastic Desktop Service console are authoritative.
To create 190 cloud computers, you need a VPC with at least 380 available IP addresses (twice the required number) to account for reserved addresses.
Start with the CIDR block
10.0.0.0and set the subnet mask to/24. The console shows 196 available IP addresses. This is fewer than the 380 required, so the subnet mask needs to be adjusted.Reset the subnet mask to
/23. The console shows 420 available IP addresses, which exceeds the 380 required.
Use 10.0.0.0/23 as the office network VPC CIDR block to support 190 cloud computers.