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How to Configure DHCP Subnets and Address Pools

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With advanced DHCP service settings enabled, you can configure DHCP subnets and address pools and assign policies for handling DHCP client groups and and Barracuda Network Access Clients.

Before You Begin

Before configuring DHCP address pools, enable advanced pool configuration in the DHCP service setup. For more information, see How to Configure Advanced DHCP Settings.

Step 1. Configure Advanced Subnets

  1. Go to CONFIGURATION > Configuration Tree >  Box  > Assigned Services  > DHCP > DHCP Enterprise Configuration .
  2. In the left menu, expand Configuration Mode and click Switch to Advanced View.
  3. In the left menu, click Address Pools.
  4. Click Lock.
  5. In the Advanced Subnets section, click + and add a subnet.
  6. Enter a Name for the subnet and click OK. The Advanced Subnets window opens.
  7. From the Used Subnet field, select a network that is configured on the Barracuda CloudGen Firewall. When configuring a relayed network, select explicit and enter the network address and mask in the Network Address field.
  8. Enter the DHCP Server Identifier that should be included in DHCPOFFER messages to let clients distinguish between multiple lease offers.
  9. From the Perform DDNS Update list, enable or deactivate DNS setting updates for subnets. You can select:
    • true – Enables DNS setting updates for subnets (The DNS Zone setting is activated) and enter the updating DNS Zone (configured within dynamic DNS).
    • false – Disables DNS setting updates for subnets.
    • not-set – (default) Enforces global DNS parameters to be used for subnets.
  10. From the Subnet Parameters list, select the DHCP parameter template if configured, which settings should be used for this subnet. For more information, see How to Configure DHCP Parameter Templates.
  11. From the Subnet DHCP Options list, select the DHCP options template for the subnet if configured. For more information, see How to Configure DHCP Option Templates.

Step 2. Configure Address Pools

Configure your address pools and define client policies.

  1. In the Address Pools section, click + to add an entry.
  2. Enter a Name for the address pool and click OK. The Address Pools window opens.
  3. Enter the first and last IP address of the pool range in the IP Begin and IP End fields.
  4. From the All Clients Policy list, select a policy for handling DHCP clients. You can select:
    • none – (Default) A global policy is not used. Instead, the policies that are specified by the Known Clients, Unknown Clients, Allowed Classes, and Denied Classes settings are used.
    • allow – All clients are allowed IP addresses from this pool.
    • deny – All clients are denied IP addresses from this pool.
  5. From the Network Access Clients Policy list, select the policy for handling Barracuda Network Access clients. You can select:
    • none – (Default) No Barracuda Network Access Clients policy is not used.
    • Network Access Clients – Barracuda Network Access Clients are allowed to receive IP addresses from the pool.
    • guests – Barracuda Network Access Clients are denied IP addresses from the pool.
  6. In the Allowed / Denied Classes tables, add the DHCP classes that are allowed or denied to get leases from the address pool. For more information, see How to Configure DHCP Classes.
  7. From the Known / Unknown Clients list, select the policy for handling known and unknown clients if a global policy is not selected from the All Clients Policy list. You can select: 
    • allow – (Default for known clients) Clients are allowed leases from the address pool.
    • deny –  (Default for unknown clients) Clients are not allowed leases from the address pool.
    • not-set – This setting is deactivated.
    For more information on specifying known clients, see How to Configure Known Clients.
  8. From the BOOTP Clients Policy list, select the dynamic-bootp flag that specifies if the DHCP server dynamically assigns addresses to bootp clients if a global policy is not selected from the All Clients Policy list. You can select:
    • allow_dynamic – Dynamic BOOTP for IP addresses are allowed.
    • deny_dynamic – Dynamic BOOTP for IP addresses are denied.
    • not-set – This setting is deactivated.
  9. Click OK.
  10. If the subnet is shared, complete Step 3 .
  11. Click Send Changes and Activate.

Step 3. Configure Shared/Multihomed Subnets

If multiple subnets have to be hosted on a single network interface, configure and specify additional subnets in the Multi Subnet Configuration section:

  1. Enable Shared Network Device if the interface must host multiple subnets. This enables Further Subnets.
  2. Select the desired parameter template from the Shared Parameters list.
  3. From the Shared DHCP Options list, select the DHCP options for the additional network.
  4. In the Further Subnets table, add any additional subnets. For each entry, you can specify settings that are similar to those in the Subnet Configuration section.
  5. Click OK.
  6. Click Send Changes and Activate.