All workstations on a network, whether it be a Local Area Net (LAN) or the World Wide Web (the Internet), must be assigned an Internet Protocol (IP) address. This is a unique number that identifies a specific workstation on the LAN or Internet. This number can be either manually assigned, or it can be automatically/dynamically assigned. The automatic assignment is done with a DHCP (Dynamic Host Configuration Protocol) server. A DHCP server simplifies IP addressing by assigning IP addresses automatically from its scope, or pool, of addresses.
What is DHCP?
DHCP is a service that automatically supplies TCP/IP addresses and configuration parameters to workstations on the network. DHCP reduces the overall administrative load by eliminating the need for an administrator to enter TCP/IP configuration information on each workstation. The DHCP service needs very little processing power, so it doesn't require a dedicated computer. In fact, it can be installed on a domain controller with very little impact.
How is a DHCP Server setup?
We have been using the LinkSys Router to serve as our DHCP server. A setup utility is included with the router. To get to the LinkSys setup utility, enter open Internet Exporer and enter 192.168.1.1 at the address line and hit Enter or Go. This will take you to the router configuration utility. Before configuring the server, you must have the following information:
- A Static IP Address (provided by your ISP)
- The Subnet mask (usually 255.255.255.0)
- the Default Gateway (provided by your ISP)
- Any DNS servers to be used, (also provided by your ISP) and
- The estimated number of nodes or workstations (so you can set the scope/pool).
The server/router must have a manually configured static IP address , subnet mask, and a default gateway. The server is also configured with "scopes," or ranges of IP addresses to distribute, along with additional configuration parameters.
Understanding your DHCP scope
The server must have a manually configured static IP address, subnet mask, and a default gateway. The server is also configured with "scopes," or ranges of IP addresses to distribute (along with additional configuration parameters). When configuring DHCP, it's important that your IP address pool is allocated correctly. That is, you need to specify the range of IP address numbers that the DHCP server can draw from for distribution among the nodes/workstations on your network. This is usually done by providing either the two extreme IP address numbers in a scope; or, by identifying the assigned static IP address, and then a number greater than the number of workstations in the network. Any IP-configured devices that cannot participate in the DHCP service—including routers, domain controllers, and IP printers—require a unique static address (these are also assigned by the ISP). Scopes configured on DHCP servers must exclude all manually configured IP addresses. A WINS server, DNS server, DHCP server, or any other computer whose IP address is specified in another host's TCP/IP configuration should not be assigned IP addresses from your DHCP scope. Microsoft recommends using static IP addresses on servers and reserving the address in a DHCP scope.
Setting up a DHCP Client Workstation
Setting up a Windows workstation requires opening the IP stack in Network Neighborhood. Using the right mouse button, Right Click on Network Neighborhood icon (on the desktop) and select Properties. Then, find and select the TCP/IP protocol for your installed network interface card (NIC). Next, with your TCP/IP protocol selected, click on the Properties button. Now select the IP Address Tab and click on the radio button option for "Obtain an IP Address Automatically". Move to the WINS Configuration Tab and make sure the "Use DHCP for WINS Resolution" radio button is selected. Now select the Gateway Tab and make sure all fields are blank. Lastly, select the DNS Configuration Tab and click on the radio button option for "Disable DNS". This will ensure all fields there are also blank. Finally, click OK and then OK again. Then you should be asked to restart your computer. Click Yes and allow the computer to restart.
Planning
Planning is most important when you have a large LAN/WAN enterprise. However, a DHCP server can generally support 10,000 clients/workstation; so, small businesses are not generally effected by DHCP limitations. Regardless, you do want to insure a stable platform for any DHCP server. You may want to consider adding processor, memory, or disk resources so the server can adequately support the added DHCP service.
A DHCP server provides a simpler IP address management capability for administrator and network users. Keep in mind that Microsoft DHCP is easiest to establish during new implementations; and, existing network clients with static IP addresses must be updated before they can accept dynamically assigned IP addresses.
