Splitting IPv4 networks - BlueCat Integrity - 9.5.0

Address Manager Administration Guide

Product name
BlueCat Integrity

With an IPv4 block created in Address Manager, you can split an IPv4 network into sub-networks.

Address Manager includes enhancements to network splitting. IPv4 networks can be split into multiple sub-networks to help you better manage your IP space.
  • Tags, deployment options, and deployment roles present on a block or network prior to a split are duplicated on the new networks. Child networks prior to a split will be assigned to the corresponding parent.
  • Users must have change, add, or full access rights on IPv4 objects to split IPv4 blocks and networks.

To split an IPv4 network:

  1. Select the IP Space tab. Tabs remember the page you last worked on, so select the tab again to ensure you're on the Configuration information page.
  2. From the configuration drop-down menu, select a configuration.
  3. Under IPv4 Blocks, select the network that you want to split.
  4. Click the menu beside the network name and select Split.
  5. From the Number of Networks drop-down menu, select the desired number of sub-networks.
    • The number of networks available for splitting depends on the size of network being split.
    • The selected number of networks determines the network size and IP addresses.
    Note: In order to support two allocatable IP addresses, /31 networks are special cases that do not have network, gateway, or broadcast addresses. Resizing or splitting larger networks to /31 will remove associated network, gateway, and broadcast addresses.
  6. Select the Preserve Gateway check box to keep the gateway of the original network. If selected, the original network’s gateway will be preserved and used in a split network even if the Default Gateway per network check box is selected. If not selected, the original network’s gateway might be deleted and associated DNS records might also be deleted. If the preserved gateway happens to be the same IP address as the default gateway that's being created in a new network, the preserved gateway will still remain.
  7. Select the Assign Addresses check box to assign the default gateway or to apply a template to new networks. Don't select this option if you will assign a custom gateway later:
    Note: The Assign Addresses check box might not be applicable depending on the number of selected networks.
    • Default Gateway per network—select this option to make the first address after the network ID the default gateway. If Preserve Gateway is selected above, this option won't apply to the network containing the preserved gateway IP address.
    • Use Template—select this option to apply a network template to your networks. From the drop-down menu, select the name of the Network Template.
      Note: Address Manager displays the error message “Split not possible” if the preserved gateway and the gateway defined in the template don't match. Change the settings or the network template to continue with the split.
  8. Click Continue.
  9. Under Network List, set the following as needed:
    • Overwrite Conflicts—select this option to resolve network conflicts and continue to split the network. If selected, conflicting objects in the original network and any linked DNS records might be removed.
    • Network Name—enter names for the networks. The network name fields will be auto-populated if there's a pre-existing network name.
  10. Click Confirm.
    Note: Messages:
    • Address Manager displays the warning message “Conflicts Detected” if it detects a conflict between the original network and newly split networks.
    • Address Manager alerts you with the error message “Split not possible” if you try to continue without resolving conflicts.
    Note: Conflicts with existing networks:

    If Address Manager detects a conflict between any of the newly created networks and the existing broadcast ID, network ID, or default gateway, you receive a warning alerting you of the conflict. You can choose to cancel your changes or overwrite the conflicts. Depending on the network being split, overwriting conflicts might delete network parameters such as a custom gateway. BlueCat advises to exercise caution when overwriting network conflicts. The Overwrite option isn't applicable to a gateway conflict with DHCP ranges.