---
sourceDocument: Australia Telecommunications Network Inventory
sourceDocumentLink: https://servicenow-prod.fluidtopics.net/r/telecom-network-inventory

 Release :

    - australia

ft:locale :

    - en-US

ft:publication_title :

    - Australia Telecommunications Network Inventory

ft:clusterId :

    - telninv

bundleId :

    - telninv

workflow :

    - Customer and Industry


---

# Create an IP Subnetwork record

# Create an IP Subnetwork record {#ariaid-title1}

Release version: Australia  
Updated September 10, 2026  
![](https://www.servicenow.com/docs/portal-asset/ico-clock) 3 minutes to read  
Create an IP Subnetwork record to subdivide an IP Address Block or to nest a subnetwork within an existing IP Subnetwork. The subnetwork's CIDR must fall within its parent's range. This task supports both IPv4 and
IPv6.

## Before you begin

Install all required [Modeling your workflow](https://servicenow-prod.fluidtopics.net/k8sddiH0kf8wEJSebhQhKA "Learn how to create a network inventory record in the Telecommunications Network Inventory application to store the details about your network assets. As you create the records, you can also define the relationship between each inventory record so that you can design a digital model of your network.") plugins.

The parent IP Address Block or IP Subnetwork must be in an active state (Life Cycle Stage = Operational and Life Cycle Stage Status = In Use).

Role required: `core.dc_ops_agent, sn_ni_core.inventory_agent`

## About this task

When you create an IP Subnetwork record, the system creates a corresponding configuration item (CI) record in the IP Network Subnet (`cmdb_ci_ip_network_subnet`) table.

An IP Subnetwork can itself contain further nested IP Subnetworks. The nesting depth is not limited. To create a nested subnetwork, start from the parent IP Subnetwork record instead of the IP Address Block.

The IP Subnetwork label in the user interface refers to the Managed IP Network Subnet class in the underlying data model.

## Procedure

1. Navigate to WorkspacesNetwork Inventory Workspace or Service Operations Workspace.
2. Open the parent record under which you want to create the subnetwork:
   * To create a top-level subnetwork, open an IP Address Block record by navigating to Inventory Number AllocationIP Address Blockand select the block.
   * To create a nested subnetwork, open an IP Subnetwork record by navigating to Inventory Number AllocationIP Network Subnets and select the subnetwork.
3. Select the IP Subnetwork tab (for top-level subnetworks) or the Nested IP Subnet tab (for nested subnetworks).
4. Select Create IP Subnetwork.
5. On the Create Nested IP Subnetwork form, fill in the fields.  
   {#create-an-ip-subnetwork-record__create-nested-ip-subnetwork-fields__entry__2}

   | Field | Description |
   |-|-|
   | Nested Pool Name | Name for this subnetwork. |
   | CIDR | The subnetwork's address range in CIDR notation. The CIDR must be a more-specific range within the parent's CIDR. The system validates the CIDR on save. For more information, see [CIDR validation rules for IP Address Blocks and IP Subnetworks](https://servicenow-prod.fluidtopics.net/pz42Yup53fGYi9ouI5lr_A "The CIDR value entered on an IP Address Block or IP Subnetwork record is validated when the record is saved. Invalid CIDR values are rejected with an inline error message; the record cannot be saved until the value passes all rules."). |
   | Managed Network | Network inherited from the parent. If the parent has a Managed Network set, this field is read-only and pre-populated with the parent's value. If the parent has no Managed Network, this field is editable. For more information, see [Managed Network form](https://servicenow-prod.fluidtopics.net/Tqzf_R_sgc~bMlW8YQUZwQ "The Managed network form enables you to manage a network in the Telecommunications Network Inventory application."). |
   | Parent Pool | The parent record. |
   | DNS Domain | DNS domain for this subnetwork. |
   | Description | Description of the subnetwork. |
   | Life cycle stage | Current lifecycle stage. This field is automatically set to Operational. |
   | Life Cycle Stage Status | Current lifecycle status. This field is automatically set to In Use. Note: The subnetwork must be Operational and In Use to support nested subnetworks and IP allocations. |
   [ ]

   {#create-an-ip-subnetwork-record__create-nested-ip-subnetwork-fields}
6. Select Submit.  
   If the CIDR fails validation, an inline error message is displayed. Common rejections include the CIDR falling outside the parent's range, the CIDR being identical to the parent, and the CIDR duplicating another subnetwork
   under the same parent. For more information about the validation rules, see [CIDR validation rules for IP Address Blocks and IP Subnetworks](https://servicenow-prod.fluidtopics.net/pz42Yup53fGYi9ouI5lr_A "The CIDR value entered on an IP Address Block or IP Subnetwork record is validated when the record is saved. Invalid CIDR values are rejected with an inline error message; the record cannot be saved until the value passes all rules.").

   After successful submission, the system navigates to the new IP Subnetwork record.
7. Create the [Modeling your workflow](https://servicenow-prod.fluidtopics.net/k8sddiH0kf8wEJSebhQhKA "Learn how to create a network inventory record in the Telecommunications Network Inventory application to store the details about your network assets. As you create the records, you can also define the relationship between each inventory record so that you can design a digital model of your network.") attributes for this IP Subnetwork by selecting Set Inventory Attributes.  
   When you select Set Inventory Attributes, the system creates a TNI CI Attributes record. The record is added to the CI table and the [Modeling your workflow](https://servicenow-prod.fluidtopics.net/k8sddiH0kf8wEJSebhQhKA "Learn how to create a network inventory record in the Telecommunications Network Inventory application to store the details about your network assets. As you create the records, you can also define the relationship between each inventory record so that you can design a digital model of your network.") CI Attributes tables, and linked to the CI record.  
   Note:  
   If you select Save without selecting Set Inventory Attributes the system creates a CI record but not a [Modeling your workflow](https://servicenow-prod.fluidtopics.net/k8sddiH0kf8wEJSebhQhKA "Learn how to create a network inventory record in the Telecommunications Network Inventory application to store the details about your network assets. As you create the records, you can also define the relationship between each inventory record so that you can design a digital model of your network.") CI record. In the Network Inventory Workspace, Set Inventory Attributes is visible only for [Modeling your workflow](https://servicenow-prod.fluidtopics.net/k8sddiH0kf8wEJSebhQhKA "Learn how to create a network inventory record in the Telecommunications Network Inventory application to store the details about your network assets. As you create the records, you can also define the relationship between each inventory record so that you can design a digital model of your network.") roles. In the TNI CI attributes form, the name is fetched from the Name field by default, and the Inventory Category is set as IP Address.
8. Add packs to this service by selecting Add Packs.
9. Add attachments such as graphics or documents by selecting the attachment icon.
10. View the hierarchy of records under this subnetwork by selecting the Dependency View option.
11. View the related network inventories by selecting the ![list icon]() list icon.  
    The Infrastructure Relationships section shows all the related network inventories grouped by the individual network instance.

## What to do next

* To allocate IP address slots in bulk, see [Allocate IP address slots in a subnetwork](https://servicenow-prod.fluidtopics.net/GNz3ONnBMKadJjPBuzh8ZQ "Allocate IP address slots to create one Allocated IP Address record for each address in a subnetwork CIDR. Reserved addresses (the first and last for IPv4, or the first for IPv6) are flagged automatically and can't be promoted to IP Address records.").
* To create IP Address records for selected slots after allocation, see [Create an IP Address record from allocated IPs](https://servicenow-prod.fluidtopics.net/hRNDS4NQVx0~F9JurffE9g "Create one or more IP Address records by selecting allocated IP slots and promoting them to active CMDB Configuration Items.").
* To create a single IP Address record at the subnetwork level, see [Create an IP Address record at subnet level](https://servicenow-prod.fluidtopics.net/q3YlFrpcnUl5o5EeYJXmVA "Create a single IP Address record that represents an entire IP Subnetwork as one Configuration Item. The IP Address record uses the subnetwork'ss CIDR as its value, rather than a single host address. This method is used when the subnetwork is bound to a service, port, customer, or interface as a single entity.") .

You can also review or update the fields, create a related tab record, or delete a record. For more information, see [Update or delete a record of an inventory number allocation](https://servicenow-prod.fluidtopics.net/ZEUnXUbjwmFicxdhOgEhwQ "Review, update, and delete a record of an IP address space element using the Telecommunications Network Inventory application.").
**Related tasks**   

* [Allocate IP address slots in a subnetwork](https://servicenow-prod.fluidtopics.net/GNz3ONnBMKadJjPBuzh8ZQ "Allocate IP address slots to create one Allocated IP Address record for each address in a subnetwork CIDR. Reserved addresses (the first and last for IPv4, or the first for IPv6) are flagged automatically and can't be promoted to IP Address records.")
* [Create an IP Address record from allocated IPs](https://servicenow-prod.fluidtopics.net/hRNDS4NQVx0~F9JurffE9g "Create one or more IP Address records by selecting allocated IP slots and promoting them to active CMDB Configuration Items.")
* [Create an IP Address record at subnet level](https://servicenow-prod.fluidtopics.net/q3YlFrpcnUl5o5EeYJXmVA "Create a single IP Address record that represents an entire IP Subnetwork as one Configuration Item. The IP Address record uses the subnetwork'ss CIDR as its value, rather than a single host address. This method is used when the subnetwork is bound to a service, port, customer, or interface as a single entity.")  
**Related reference**   

* [CIDR validation rules for IP Address Blocks and IP Subnetworks](https://servicenow-prod.fluidtopics.net/pz42Yup53fGYi9ouI5lr_A "The CIDR value entered on an IP Address Block or IP Subnetwork record is validated when the record is saved. Invalid CIDR values are rejected with an inline error message; the record cannot be saved until the value passes all rules.")
* [Hierarchy rules for IP Subnetworks](https://servicenow-prod.fluidtopics.net/w23g6E9ewprlk5TMK~fNmQ "These rules apply only when creating or updating an IP Subnetwork (which always has a parent — either an IP Address Block or another IP Subnetwork).")
* [IP Subnetwork form](https://servicenow-prod.fluidtopics.net/FCJ5Na8kJ40qK1t_dzCQXQ "The IP Subnetwork form defines a subdivision of an IP Address Block or a nested subdivision of another IP Subnetwork.")

*[\>]: and then