AWS CLI Command Reference

[ aws . ec2 ]

create-subnet

Description

Creates a subnet in a specified VPC.

You must specify an IPv4 CIDR block for the subnet. After you create a subnet, you can’t change its CIDR block. The allowed block size is between a /16 netmask (65,536 IP addresses) and /28 netmask (16 IP addresses). The CIDR block must not overlap with the CIDR block of an existing subnet in the VPC.

If you’ve associated an IPv6 CIDR block with your VPC, you can create a subnet with an IPv6 CIDR block that uses a /64 prefix length.

Warning

AWS reserves both the first four and the last IPv4 address in each subnet’s CIDR block. They’re not available for use.

If you add more than one subnet to a VPC, they’re set up in a star topology with a logical router in the middle.

When you stop an instance in a subnet, it retains its private IPv4 address. It’s therefore possible to have a subnet with no running instances (they’re all stopped), but no remaining IP addresses available.

For more information about subnets, see Your VPC and Subnets in the Amazon Virtual Private Cloud User Guide .

See also: AWS API Documentation

See ‘aws help’ for descriptions of global parameters.

Synopsis

  create-subnet
[--tag-specifications <value>]
[--availability-zone <value>]
[--availability-zone-id <value>]
--cidr-block <value>
[--ipv6-cidr-block <value>]
[--outpost-arn <value>]
--vpc-id <value>
[--dry-run | --no-dry-run]
[--cli-input-json | --cli-input-yaml]
[--generate-cli-skeleton <value>]

Options

--tag-specifications (list)

The tags to assign to the subnet.

(structure)

The tags to apply to a resource when the resource is being created.

ResourceType -> (string)

The type of resource to tag. Currently, the resource types that support tagging on creation are: capacity-reservation | carrier-gateway | client-vpn-endpoint | customer-gateway | dedicated-host | dhcp-options | egress-only-internet-gateway | elastic-ip | elastic-gpu | export-image-task | export-instance-task | fleet | fpga-image | host-reservation | image | import-image-task | import-snapshot-task | instance | internet-gateway | ipv4pool-ec2 | ipv6pool-ec2 | key-pair | launch-template | local-gateway-route-table-vpc-association | placement-group | prefix-list | natgateway | network-acl | network-interface | reserved-instances |route-table | security-group | snapshot | spot-fleet-request | spot-instances-request | snapshot | subnet | traffic-mirror-filter | traffic-mirror-session | traffic-mirror-target | transit-gateway | transit-gateway-attachment | transit-gateway-multicast-domain | transit-gateway-route-table | volume |vpc | vpc-peering-connection | vpc-endpoint (for interface and gateway endpoints) | vpc-endpoint-service (for AWS PrivateLink) | vpc-flow-log | vpn-connection | vpn-gateway .

To tag a resource after it has been created, see CreateTags .

Tags -> (list)

The tags to apply to the resource.

(structure)

Describes a tag.

Key -> (string)

The key of the tag.

Constraints: Tag keys are case-sensitive and accept a maximum of 127 Unicode characters. May not begin with aws: .

Value -> (string)

The value of the tag.

Constraints: Tag values are case-sensitive and accept a maximum of 255 Unicode characters.

Shorthand Syntax:

ResourceType=string,Tags=[{Key=string,Value=string},{Key=string,Value=string}] ...

JSON Syntax:

[
  {
    "ResourceType": "client-vpn-endpoint"|"customer-gateway"|"dedicated-host"|"dhcp-options"|"egress-only-internet-gateway"|"elastic-ip"|"elastic-gpu"|"export-image-task"|"export-instance-task"|"fleet"|"fpga-image"|"host-reservation"|"image"|"import-image-task"|"import-snapshot-task"|"instance"|"internet-gateway"|"key-pair"|"launch-template"|"local-gateway-route-table-vpc-association"|"natgateway"|"network-acl"|"network-interface"|"network-insights-analysis"|"network-insights-path"|"placement-group"|"reserved-instances"|"route-table"|"security-group"|"snapshot"|"spot-fleet-request"|"spot-instances-request"|"subnet"|"traffic-mirror-filter"|"traffic-mirror-session"|"traffic-mirror-target"|"transit-gateway"|"transit-gateway-attachment"|"transit-gateway-connect-peer"|"transit-gateway-multicast-domain"|"transit-gateway-route-table"|"volume"|"vpc"|"vpc-peering-connection"|"vpn-connection"|"vpn-gateway"|"vpc-flow-log",
    "Tags": [
      {
        "Key": "string",
        "Value": "string"
      }
      ...
    ]
  }
  ...
]

--availability-zone (string)

The Availability Zone or Local Zone for the subnet.

Default: AWS selects one for you. If you create more than one subnet in your VPC, we do not necessarily select a different zone for each subnet.

To create a subnet in a Local Zone, set this value to the Local Zone ID, for example us-west-2-lax-1a . For information about the Regions that support Local Zones, see Available Regions in the Amazon Elastic Compute Cloud User Guide .

To create a subnet in an Outpost, set this value to the Availability Zone for the Outpost and specify the Outpost ARN.

--availability-zone-id (string)

The AZ ID or the Local Zone ID of the subnet.

--cidr-block (string)

The IPv4 network range for the subnet, in CIDR notation. For example, 10.0.0.0/24 . We modify the specified CIDR block to its canonical form; for example, if you specify 100.68.0.18/18 , we modify it to 100.68.0.0/18 .

--ipv6-cidr-block (string)

The IPv6 network range for the subnet, in CIDR notation. The subnet size must use a /64 prefix length.

--outpost-arn (string)

The Amazon Resource Name (ARN) of the Outpost. If you specify an Outpost ARN, you must also specify the Availability Zone of the Outpost subnet.

--vpc-id (string)

The ID of the VPC.

--dry-run | --no-dry-run (boolean)

Checks whether you have the required permissions for the action, without actually making the request, and provides an error response. If you have the required permissions, the error response is DryRunOperation . Otherwise, it is UnauthorizedOperation .

--cli-input-json | --cli-input-yaml (string) Reads arguments from the JSON string provided. The JSON string follows the format provided by --generate-cli-skeleton. If other arguments are provided on the command line, those values will override the JSON-provided values. It is not possible to pass arbitrary binary values using a JSON-provided value as the string will be taken literally. This may not be specified along with --cli-input-yaml.

--generate-cli-skeleton (string) Prints a JSON skeleton to standard output without sending an API request. If provided with no value or the value input, prints a sample input JSON that can be used as an argument for --cli-input-json. Similarly, if provided yaml-input it will print a sample input YAML that can be used with --cli-input-yaml. If provided with the value output, it validates the command inputs and returns a sample output JSON for that command.

See ‘aws help’ for descriptions of global parameters.

Examples

Example 1: To create a subnet with an IPv4 CIDR block

The following create-subnet example creates a subnet in the specified VPC with the specified IPv4 CIDR block. We recommend that you let us select an Availability Zone for you. Alternatively, you can use the --availability-zone option to specify the Availability Zone.

aws ec2 create-subnet \
    --vpc-id vpc-081ec835f3EXAMPLE \
    --cidr-block 10.0.1.0/24

Output:

{
    "Subnet": {
        "AvailabilityZone": "us-east-2c",
        "AvailabilityZoneId": "use2-az3",
        "AvailableIpAddressCount": 251,
        "CidrBlock": "10.0.1.0/24",
        "DefaultForAz": false,
        "MapPublicIpOnLaunch": false,
        "State": "pending",
        "SubnetId": "subnet-0e3f5cac72EXAMPLE",
        "VpcId": "vpc-081ec835f3EXAMPLE",
        "OwnerId": "111122223333",
        "AssignIpv6AddressOnCreation": false,
        "Ipv6CidrBlockAssociationSet": [],
        "SubnetArn": "arn:aws:ec2:us-east-2:111122223333:subnet/subnet-0e3f5cac72375030d"
    }
}

For more information, see Creating a Subnet in Your VPC in the AWS VPC User Guide

Example 2: To create a subnet with an IPv6 CIDR block

The following create-subnet example creates a subnet in the specified VPC with the specified IPv4 and IPv6 CIDR blocks (from the ranges of the VPC).

aws ec2 create-subnet \
 --vpc-id vpc-07e8ffd50fEXAMPLE \
 --cidr-block 10.0.0.0/24 \
 --ipv6-cidr-block 2600:1f16:115:200::/64

Output:

{
    "Subnet": {
        "AvailabilityZone": "us-east-2b",
        "AvailabilityZoneId": "use2-az2",
        "AvailableIpAddressCount": 251,
        "CidrBlock": "10.0.0.0/24",
        "DefaultForAz": false,
        "MapPublicIpOnLaunch": false,
        "State": "pending",
        "SubnetId": "subnet-02bf4c428bEXAMPLE",
        "VpcId": "vpc-07e8ffd50EXAMPLE",
        "OwnerId": "1111222233333",
        "AssignIpv6AddressOnCreation": false,
        "Ipv6CidrBlockAssociationSet": [
            {
                "AssociationId": "subnet-cidr-assoc-002afb9f3cEXAMPLE",
                "Ipv6CidrBlock": "2600:1f16:115:200::/64",
                "Ipv6CidrBlockState": {
                    "State": "associating"
                }
            }
        ],
        "SubnetArn": "arn:aws:ec2:us-east-2:111122223333:subnet/subnet-02bf4c428bEXAMPLE"
    }
}

For more information, see Creating a Subnet in Your VPC in the AWS VPC User Guide.

Output

Subnet -> (structure)

Information about the subnet.

AvailabilityZone -> (string)

The Availability Zone of the subnet.

AvailabilityZoneId -> (string)

The AZ ID of the subnet.

AvailableIpAddressCount -> (integer)

The number of unused private IPv4 addresses in the subnet. The IPv4 addresses for any stopped instances are considered unavailable.

CidrBlock -> (string)

The IPv4 CIDR block assigned to the subnet.

DefaultForAz -> (boolean)

Indicates whether this is the default subnet for the Availability Zone.

MapPublicIpOnLaunch -> (boolean)

Indicates whether instances launched in this subnet receive a public IPv4 address.

MapCustomerOwnedIpOnLaunch -> (boolean)

Indicates whether a network interface created in this subnet (including a network interface created by RunInstances ) receives a customer-owned IPv4 address.

CustomerOwnedIpv4Pool -> (string)

The customer-owned IPv4 address pool associated with the subnet.

State -> (string)

The current state of the subnet.

SubnetId -> (string)

The ID of the subnet.

VpcId -> (string)

The ID of the VPC the subnet is in.

OwnerId -> (string)

The ID of the AWS account that owns the subnet.

AssignIpv6AddressOnCreation -> (boolean)

Indicates whether a network interface created in this subnet (including a network interface created by RunInstances ) receives an IPv6 address.

Ipv6CidrBlockAssociationSet -> (list)

Information about the IPv6 CIDR blocks associated with the subnet.

(structure)

Describes an IPv6 CIDR block associated with a subnet.

AssociationId -> (string)

The association ID for the CIDR block.

Ipv6CidrBlock -> (string)

The IPv6 CIDR block.

Ipv6CidrBlockState -> (structure)

Information about the state of the CIDR block.

State -> (string)

The state of a CIDR block.

StatusMessage -> (string)

A message about the status of the CIDR block, if applicable.

Tags -> (list)

Any tags assigned to the subnet.

(structure)

Describes a tag.

Key -> (string)

The key of the tag.

Constraints: Tag keys are case-sensitive and accept a maximum of 127 Unicode characters. May not begin with aws: .

Value -> (string)

The value of the tag.

Constraints: Tag values are case-sensitive and accept a maximum of 255 Unicode characters.

SubnetArn -> (string)

The Amazon Resource Name (ARN) of the subnet.

OutpostArn -> (string)

The Amazon Resource Name (ARN) of the Outpost.

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