Managing DHCP exclusions - User Guide - BlueCat Horizon

Adding exclusions

If you want to exclude an IP address or range of addresses from a specific DHCP scope, you can add exclusions to prevent them from being used.

To create an exclusion:

1. In the list on the Networks tab of the IPAM page, select the relevant scope.
2. Use either the Action menu or the ellipses in the row to select Manage DHCP pools.
3. Select Add exclusion.
   
   
4. In the Add exclusion dialog, enter the range of addresses to be excluded in the From and To fields. All addresses within this range, including the start and end addresses, will be excluded.
5. Select Add.
6. In the Manage DHCP pools dialog, select Save.

Editing and removing exclusions

If needed you can edit and/or remove an exclusion from a DHCP scope.

To edit or remove an existing exclusion:

1. In the list on the Networks tab of the IPAM page, select the relevant scope.
2. Use either the Action menu or the ellipses in the row to select Manage DHCP pools.
3. In the Manage DHCP pools dialog, select the exclusion you want to edit or remove.
4. Use the the ellipses in the exclusion's row to select either Edit to edit the exclusion or Remove to remove it.
5. Select Save.

Adding DHCPv6 exclusions

You can create an exclusion range within a DHCPv6 scope to prevent the DHCP server from assigning IP addresses within that range. This allows you to manually assign those addresses without conflicts.

When managing exclusions within a DHCPv6 pool, you have the option to specify a percentage of the DHCPv6 scope instead of manually entering the From address and To address.

To add an exclusion:

1. In the list on the Networks tab of the IPAM page, select the desired DHCP scope.
2. Use either the Action menu or the ellipses in the row to select Manage DHCP exclusions.
3. Select Add exclusion.
4. In the Add exclusion dialog, select one of the following methods to create the exclusion range:
   • Percentage: Drag the percentage bar to the correct percentage of addresses you want to exclude and only enter a From address.
   • Manual entry: Enter the From address and To address for the range you want to exclude from the DHCP scope.
   
   
   
   Note: If the exclusion range doesn’t have the space to accommodate the specified percentage of IP addresses, it will not allow you to add this exclusion range. Adjust the From address or lower the percentage as needed.
5. Select Add.

The Manage DHCP exclusions dialog displays the following information:

• Red bar: Represents the exclusion range.
• Blue bar: Represents the address pool of dynamic allocation addresses.