Configuring DHCP Servers
When configuring a DHCP server, you must configure the server properties, policies, and associated DHCP options. Cisco Prime IP Express needs:
- The DHCP server IP address.
- One or more scopes (see the Managing Scopes) and/or prefixes.
General Configuration Guidelines
Here are some guidelines to consider before configuring a DHCP server:
- Separate the DHCP server from secondary DNS servers used for DNS updating —To ensure that the DHCP server is not adversely affected during large zone transfers, it should run on a different cluster than your secondary DNS servers.
- Lease times —See the Guidelines for Lease Times.
Configuring DHCP Server Interfaces
To configure the DHCP server, accept the Cisco Prime IP Express defaults or supply the data explicitly:
- Network interface —Ethernet card IP address, which must be static and not assigned by DHCP.
- Subnet mask —Identifies the interface network membership. The subnet mask is usually based on the network class of the interface address, in most cases 255.255.255.0.
By default, the DHCP server uses the operating system support to automatically enumerate the active interfaces on the machine and listens on all of them. You can also manually configure the server interface. You should statically configure all the IP addresses assigned to NIC cards on the machine where the DHCP server resides. The machine should not be a BOOTP or DHCP client.
Unless you have a specific need to restrict the interfaces used for DHCP, it is recommended that you do not configure specific DHCP Server interfaces. Allow the server to automatically discover the available interfaces.
Local Advanced Web UI
From the Operate menu, choose Manage Servers under the Servers submenu to open the Manage Servers page.
Select the Local DHCP server on the Manager Servers pane.
Click the Network Interfaces tab to view the available network interfaces that you can configure for the server. By default, the server uses all of them.
To configure an interface, click the Edit icon in the Configure column for the interface. This adds the interface to the Configured Interfaces table, where you can edit or delete it.
Clicking the name of the configured interface opens the Edit DHCP Server Network Interface page, where you can change the address and ports (in Expert mode) of the interface.
Click Save when you are done editing.
Click Revert to return to the Manage Servers page.
Use dhcp-interface to manually control which network interface cards’ IP addresses the DHCP server will listen on for DHCP clients. By default, the DHCP server automatically uses all your server network interfaces, so use this command to be more specific about which ones to use.
To troubleshoot and confirm validity of the configuration changes.
- Reload the DHCP server.
- Check the dhcp_startup_log and/or name_dhcp_1_log file.
For information on Log Settings, see Tuning the DHCP Server