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Resizing DHCP Scopes

You can resize a subnet to increase the number of IP addresses whenever necessary or when you see an alert icon next to the subnet. The alert icon appears when the subnet usage reaches or exceeds the threshold configured in the automated scope management configuration. For information about Automated Scope Management, see Configuring Global DHCP Properties. Universal DDI provides a few options for you to resize your subnets based on the global parameters and its analysis on your network usage.


Note

When you resize a network to a smaller netmask, you increase the number of IP addresses within that network. Universal DDI provides suggestions only if the resized network does not exceed the upper network limit or create orphan objects. When a network has a parent network or subnets, you cannot resize the subnet beyond the upper limit of the network size. For example, if a network has a /16 parent network, you cannot resize the network to a network that is larger than /16.

Resizing of DHCP scope is unavailable for /32 (for IPv4) and /128 (for IPv6) networks. 

To resize a subnet, complete the following:

  1. From the Infoblox Portal, click Configure > Networking > IPAM/DHCP > Address Spaces.
  2. Select a subnet and click ☰> Resize DHCP Scope.
  3. On the Resize DHCP Scope page, Universal DDI offers the following options:
    • Option A SCOPE EXPANSION: This option suggests an expansion to the IP address range or scope. If this option is available and recommended, the portal displays the original range and its current utilization as a reference. You can then review the list of suggested ranges and select the one that suits your business needs. You can also manually create a range by entering the start and end addresses of the range. Or you can move the slider forward, backward, or in both directions to expand the range, but you must not exclude any existing addresses in the desired range.
    • Option B SUBNET EXPANSION: This option suggests an increase in IP addresses within the subnet itself. Based on the recommendations, you can expand your subnet either forward or backward, but not in both directions. You can also create a new range by entering the start and end addresses or by using the slider to select the range.
    • Option C SUPPRESS NOTIFICATION: You can select this option to suppress notifications. When you select this option, it overrides the global parameter.
      From the drop-down menu, select one of the following:
      • Day: Specify the number of days for which you want to suppress notifications.
      • Disable: Disable the suppression of notifications. If you have not enabled notifications at the global level, you will enable notifications for this subnet by selecting this option.
      • Permanently: When you select this, you permanently disable notifications for this subnet until you modify this option or inherit the global parameter (if notification was enabled).

        Note

        When you expand a subnet, you must reconfigure all the routers and other statically assigned computers.

  4. Click Save & Close to save the details or click Cancel to exit.

Note

The DHCP scope resizing should not have any impact on current existing leases and fixed IP addresses. However, it’s always a best practice to schedule a short maintenance window for the resizing changes.