How to Configure the DHCP Service

Configure the DHCP service and specify a network range from which the IP address for the clients will be assigned. In the advanced settings for DHCP, you can configure additional service availability settings,and set up HA synchronization.

Configure the DHCP Service

1. Go to CONFIGURATION > Configuration Tree > Box > Assigned Services > DHCP-Service > DHCP Enterprise Configuration.
2. Click Lock.
3. In the left menu, select Operational Setup IPv4 or 6.
4. In the Address Pool Configuration window, enable DHCP.
5. Click + to add an entry to the  Subnets  table .
6. Enter a descriptive name for the subnet and click OK. The Subnets configuration window opens.

7. From the Used Subnet list, select one of the available IPv4 subnets or select explicit and enter the IP address in the Network Address field.

   When using IPv6 select any (stateless dhcp) to use DHCPv6 to extend IPv6 with DHCP capabilities (assigning domain name or DNS servers).

8. In the DHCP Server Identifier field, enter the IP address of the server. This IP address is provided to the client.
9. Click + to add a new entry to the Pool Ranges  table.
10. Specify the following for each range:
    • IP Begin –  The first IP address in the network range. E.g.: 10.10.10.20
    • IP End –  The last IP address in the network range. E.g.: 10.10.10.40
11. Click OK.     
12. (optional) Add MAC to IP address mappings to the Reservations table:    
    
    1. Enter the Reserved IP for the client.
       

    2. Enter the MAC Address of the client.

13. Click OK.
14. In the Router table, add the default gateway IP address. E.g.: 10.10.10.100
15. In the DNS Servers table, add the DNS server IP address. E.g.: 10.10.10.100
16. Enter the Domain Name if the client range is part of a domain.
17. Enter the NIS Domain Name and specify the details required for all servers that should be assigned.
18. In the Static Route Net table, click + to add static routes that the client should install in its routing cache. If there are multiple routes to the same destination, list them in descending order of priority.
    1. In the Static Route Net  field, enter  the destination IP address.
    2. In the Static Route GW  field, e nter  the IP address of the router.
    3. Click OK .
19. Enter the TFTP Server Name i f the 'sname' field in the DHCP header has been used for DHCP options.
20. Enter the TFTP Server IP Address for Cisco CallManager devices. In this field, you can enter a comma-delimited list of addresses.
21. Enter the Boot File Name i f the 'file' field in the DHCP header has been used for DHCP options.

22. If you set the  Barracuda Network Access Clients Policy  of an  Address Pool  to  Barracuda Network Access Clients  or  guests , add the required info to the Access Control Service IPs/Names table for a client to receive valid policy server information.

    You can add vendor IDs, policy server IP addresses, or DNS resolvable policy server names. If the  Barracuda Network Access Clients Policy  field is set to  none , the information in the  Access Control Service IPs/Names  table is ignored.

23. For information on dynamic DNS configuration, refer to How to Configure DHCP with Dynamic DNS .
24. For information on lease configuration, refer to How to Configure DHCP Parameter Templates .
25. Click OK.
26. Click Send Changes and Activate.

Check the DHCP Server Status

Click the  DHCP Tab to check the real-time status of the configured DHCP server. 

Configure Advanced DHCP Settings

1. Go to CONFIGURATION > Configuration Tree > Box > Assigned Services > DHCP-Service > DHCP Enterprise Configuration .
2. From the left Configuration Mode menu, select Switch to  Advanced View.
3. Click Lock.
4. In the left pane, select Operational Setup IPv4 or 6.
5. In the  Address Pool Configuration  window, enable DHCP.
6. Enable Use Advanced Pool Configuration. This disables the Subnets section and allows configuration of address pools.
7. In the DHCP Server Identifier field, enter the name of the server. This name is provided to the client.

8. Enable Server Is Authoritative.

   When the DHCP server receives a DHCPREQUEST message from a DHCP client requesting a specific IP address, the DHCP protocol requires that the server determines whether the IP address is valid for the network to which the client is attached. If the address is not valid, the DHCP server should respond with a DHCPNAK message, forcing the client to acquire a new IP address. To make this determination for IP addresses on a particular network segment, the DHCP server must have complete configuration information for that network segment. Unfortunately, it is not safe to assume that DHCP servers are configured with complete information. Therefore, the DHCP server normally assumes that it does not have complete information and, thus, is not sufficiently authoritative to safely send DHCPNAK messages as required by the protocol.

9. Select the UDP Listen Port on which the DHCP server listens for DHCP requests. By default, the server listens on port 67.

10. For an HA setup, edit the settings in the HA Synchronization Setup section to synchronize the DHCP database between both units:
    1. Enable HA Synchronization to synchronize the DHCP database between the HA units.
    2. Specify the HA synchronization interval if required (default: 300 seconds).
11. Click Send Changes and Activate.