(Optional) Creating a Subnet for the VPC¶
Scenarios¶
A VPC comes with a default subnet. If the default subnet cannot meet your requirements, you can create one.
The subnet is configured with DHCP by default. When an ECS using this VPC starts, the ECS automatically uses DHCP to obtain an IP address.
Procedure¶
Log in to the management console.
Click
in the upper left corner and select the desired region and project.On the console homepage, under Network, click Virtual Private Cloud.
In the navigation pane on the left, click Virtual Private Cloud.
On the Virtual Private Cloud page, locate the VPC for which a subnet is to be created and click the VPC name.
On the displayed Subnets tab, click Create Subnet.
Configure the required parameters.
Figure 1 Create Subnet¶
Table 1 Parameter descriptions¶ Parameter
Description
Example Value
AZ
The AZ of a VPC subnet.
eu-ch2-01
Name
The subnet name.
The name can contain a maximum of 64 characters, including only letters, digits, underscores (_), hyphens (-), and periods (.). Spaces are not allowed.
Subnet
IPv4 CIDR Block
The CIDR block for the subnet. This value must be within the VPC CIDR block.
192.168.0.0/24
IPv6 CIDR Block
Specifies whether to enable IPv6.
After the IPv6 function is enabled, the system automatically assigns an IPv6 CIDR block to the created subnet. Currently, the IPv6 CIDR block cannot be customized. IPv6 cannot be disabled after the subnet is created.
-Advanced Settings
Click the drop-down arrow to set advanced settings for the subnet, including Gateway and DNS Server Address.
Default
Gateway
The gateway address of the subnet.
192.168.0.1
DNS Server Address
By default, two DNS server addresses are configured. You can change them if necessary. A maximum of five DNS server addresses can be configured. Multiple IP addresses must be separated using commas (,).
100.125.x.x
Tag
The subnet tag, which consists of a key and value pair. You can add a maximum of ten tags to each subnet.
The tag key and value must meet the requirements listed in Table 2.
Key: subnet_key1
Value: subnet-01
Description
Supplementary information about the subnet. This parameter is optional.
The description can contain a maximum of 255 characters and cannot contain angle brackets (< or >).
-Table 2 Subnet tag key and value requirements¶ Parameter
Requirements
Example Value
Key
Cannot be left blank.
Must be unique for each subnet.
Can contain a maximum of 36 characters.
Can contain only the following character types:
Uppercase letters
Lowercase letters
Digits
Special characters, including hyphens (-) and underscores (_)
subnet_key1
Value
Can contain a maximum of 43 characters.
Can contain only the following character types:
Uppercase letters
Lowercase letters
Digits
Special characters, including hyphens (-) and underscores (_)
subnet-01
Click OK.
Notes¶
When a subnet is created, there are five reserved IP addresses, which cannot be used. For example, in a subnet with CIDR block 192.168.0.0/24, the following IP addresses are reserved:
192.168.0.0: Network ID. This address is the beginning of the private IP address range and will not be assigned to any instance.
192.168.0.1: Gateway address.
192.168.0.253: Reserved for the system interface. This IP address is used by the VPC for external communication.
192.168.0.254: DHCP service address.
192.168.0.255: Network broadcast address.
If you set Advanced Settings to Custom during subnet creation, the reserved IP addresses may be different from the default ones, but there will still be five of them. The specific addresses depend on your subnet settings.