# Creating a Subnet

#### Function

This API is used to create a subnet.

#### URI

POST /v1/{project_id}/subnets

Table 1 describes the parameters.

Table 1 Parameter description
Name | Mandatory | Description
--- | --- | ---
project_id | Yes | Specifies the project ID.

#### Request Message

- Request parameter

  Table 2 Request parameter
  Name | Mandatory | Type | Description
  --- | --- | --- | ---
  subnet | Yes | subnet object | Specifies the subnet objects.

  Table 3 subnet objects
  Name | Mandatory | Type | Description
  --- | --- | --- | ---

  name

  Yes

  String

  - Specifies the subnet name.
  - The value can contain 1 to 64 characters, including letters, digits, underscores (_), hyphens (-), and periods (.).

  description

  No

  String

  - Provides supplementary information about the subnet.
  - The value can contain no more than 255 characters and cannot contain angle brackets (< or >).

  cidr

  Yes

  String

  - Specifies the subnet CIDR block.
  - The value must be within the VPC CIDR block.
  - The value must be in CIDR format. The subnet mask cannot be greater than 28.

  gateway_ip

  Yes

  String

  - Specifies the gateway of the subnet.
  - The value must be an IP address in the subnet.
  - The value must be a valid IP address.

  dhcp_enable

  No

  Boolean

  - Specifies whether DHCP is enabled for the subnet.
  - The value can be true (enabled) or false (disabled).
  - If this parameter is left blank, the system automatically sets it to true by default. If this parameter is set to false, newly created ECSs cannot obtain IP addresses, and usernames and passwords cannot be injected using Cloud-init. Exercise caution when performing this operation.

  primary_dns

  No

  String

  - Specifies the IP address of DNS server 1 on the subnet.
  - The value must be an IP address. If the value is not specified, the default value will be left blank.

  secondary_dns

  No

  String

  - Specifies the IP address of DNS server 2 on the subnet.
  - The value must be an IP address. If the value is not specified, the default value will be left blank.

  dnsList

  No

  Array of strings

  - Specifies the DNS server address list of a subnet. This field is required if you need to use more than two DNS servers.
  - This parameter value is the superset of both DNS server address 1 and DNS server address 2. If the value is not specified, the default value will be left blank.

  availability_zone

  No

  String

  - Specifies the AZ to which the subnet belongs, which can be obtained from endpoints.
  - The value must be an existing AZ in the system. If the value is not specified, the default value will be left blank.

  vpc_id | Yes | String | Specifies the ID of the VPC to which the subnet belongs.
  extra_dhcp_opts | No | Array of extra_dhcp_opt objects | Specifies the NTP server address configured for the subnet. For details, see Table 4.

  Table 4 extra_dhcp_opt object
  Name | Mandatory | Type | Description
  --- | --- | --- | ---

  opt_value

  No

  String

  - Specifies the NTP server address configured for the subnet.
  - Constraints:

    The option ntp for opt_name indicates the NTP server configured for the subnet. Currently, only IPv4 addresses are supported. A maximum of four IP addresses can be configured, and each address must be unique. Multiple IP addresses must be separated using commas (,). The option null for opt_name indicates that no NTP server is configured for the subnet. The parameter value cannot be an empty string.

  opt_name

  Yes

  String

  - Specifies the NTP server address name configured for the subnet.
  - Currently, the value can only be set to ntp.

- Example request

      POST https://{Endpoint}/v1/{project_id}/subnets

      {
          "subnet": {
              "name": "subnet",
              "description": "",
              "cidr": "192.168.20.0/24",
              "gateway_ip": "192.168.20.1",
              "dhcp_enable": true,
              "primary_dns": "114.xx.xx.114",
              "secondary_dns": "114.xx.xx.115",
              "dnsList": [
                  "114.xx.xx.114",
                  "114.xx.xx.115"
              ],
              "availability_zone": "aa-bb-cc",//For example, the AZ is aa-bb-cc.
              "vpc_id": "3ec3b33f-ac1c-4630-ad1c-7dba1ed79d85",
              "extra_dhcp_opts": [
                  {
                      "opt_value": "10.100.0.33,10.100.0.34",
                      "opt_name": "ntp"
                  }
              ]
          }
      }

#### Response Message

- Response parameter

  Table 5 Response parameter
  Name | Type | Description
  --- | --- | ---
  subnet | subnet object | Specifies the subnet objects.

  Table 6 subnet objects
  Name | Type | Description
  --- | --- | ---
  id | String | Specifies the resource identifier in the form of UUID.

  name

  String

  - Specifies the subnet name.
  - The value can contain 1 to 64 characters, including letters, digits, underscores (_), hyphens (-), and periods (.).

  description

  String

  - Provides supplementary information about the subnet.
  - The value can contain no more than 255 characters and cannot contain angle brackets (< or >).

  cidr

  String

  - Specifies the subnet CIDR block.
  - The value must be within the VPC CIDR block.
  - The value must be in CIDR format. The subnet mask cannot be greater than 28.

  gateway_ip

  String

  - Specifies the gateway of the subnet.
  - The value must be an IP address in the subnet.
  - The value must be a valid IP address.

  dhcp_enable | Boolean | Specifies whether the DHCP function is enabled for the subnet.

  primary_dns

  String

  - Specifies the IP address of DNS server 1 on the subnet.
  - The value must be an IP address. If the value is not specified, the default value will be left blank.

  secondary_dns

  String

  - Specifies the IP address of DNS server 2 on the subnet.
  - The value must be an IP address. If the value is not specified, the default value will be left blank.

  dnsList

  Array of strings

  - Specifies the DNS server address list of a subnet. This field is required if you need to use more than two DNS servers.
  - This parameter value is the superset of both DNS server address 1 and DNS server address 2. If the value is not specified, the default value will be left blank.

  availability_zone

  String

  - Specifies the AZ to which the subnet belongs, which can be obtained from endpoints.
  - The value must be an existing AZ in the system. If the value is not specified, the default value will be left blank.

  vpc_id | String | Specifies the ID of the VPC to which the subnet belongs.

  status

  String

  - Specifies the status of the subnet.
  - The value can be ACTIVE, UNKNOWN, or ERROR.
    - ACTIVE: indicates that the subnet has been associated with a VPC.
    - UNKNOWN: indicates that the subnet has not been associated with a VPC.
    - ERROR: indicates that the subnet is abnormal.
  - The system creates a subnet and then associates the subnet with a VPC in the threads.

    In the concurrent scenario, if the CIDR block of the created subnet is the same as that of an existing subnet, the created subnet fails to associate with a VPC after underlying system verification. As a result, the subnet creation fails.

    In this scenario, the returned value of status is UNKNOWN.

  neutron_network_id | String | Specifies the ID of the corresponding network (OpenStack Neutron API).
  neutron_subnet_id | String | Specifies the ID of the corresponding subnet (OpenStack Neutron API).
  extra_dhcp_opts | Array of extra_dhcp_opt objects | Specifies the NTP server address configured for the subnet. For details, see Table 7.

  Table 7 extra_dhcp_opt object
  Name | Mandatory | Type | Description
  --- | --- | --- | ---

  opt_value

  No

  String

  - Specifies the NTP server address configured for the subnet.
  - Constraints:

    The option ntp for opt_name indicates the NTP server configured for the subnet. Currently, only IPv4 addresses are supported. A maximum of four IP addresses can be configured, and each address must be unique. Multiple IP addresses must be separated using commas (,). The option null for opt_name indicates that no NTP server is configured for the subnet. The parameter value cannot be an empty string.

  opt_name

  Yes

  String

  - Specifies the NTP server address name configured for the subnet.
  - Currently, the value can only be set to ntp.

- Example response

      {
          "subnet": {
              "id": "4779ab1c-7c1a-44b1-a02e-93dfc361b32d",
              "name": "subnet",
              "description": "",
              "cidr": "192.168.20.0/24",
              "dnsList": [
                  "114.xx.xx.114",
                  "114.xx.xx.115"
              ],
              "status": "UNKNOWN",
              "vpc_id": "3ec3b33f-ac1c-4630-ad1c-7dba1ed79d85",
              "gateway_ip": "192.168.20.1",
              "dhcp_enable": true,
              "primary_dns": "114.xx.xx.114",
              "secondary_dns": "114.xx.xx.115",
              "availability_zone": "aa-bb-cc",//For example, the AZ is aa-bb-cc.
              "neutron_network_id": "4779ab1c-7c1a-44b1-a02e-93dfc361b32d",
              "neutron_subnet_id": "213cb9d-3122-2ac1-1a29-91ffc1231a12"
              "extra_dhcp_opts": [
                  {
                      "opt_value": "10.100.0.33,10.100.0.34",
                      "opt_name": "ntp"
                  }
              ]
          }
      }

#### Status Code

See Status Codes.

#### Error Code

See Error Codes.

Parent topic: Subnet