Planning for DHCP Implementation

This section describes how to develop strategies for implementing DHCP servers in small LANs or large routed networks. Most network administrators implementing DHCP will also be planning a strategy for implementing WINS servers. The planning tasks described here also apply to WINS servers. In fact, the administrator will probably want to plan DHCP and WINS implementation in tandem.

Note

If you use DHCP servers, you must use WINS servers so that the dynamic IP addressing of DHCP clients can be dynamically updated in name- to- IP- address mappings.

Before you install Microsoft DHCP servers on your network, consider the following recommendations:

• The general guideline for determining how many DHCP servers are needed in a network is that one online DHCP server and one backup DHCP server (a hot standby) can support 10,000 clients. However, when deciding how many DHCP servers you will need, consider the location of routers on the network and whether you will want a DHCP server in each subnet.
• To determine where to install the DHCP servers, use the physical characteristics of your LAN or WAN infrastructure and not the logical groupings defined in the Windows NT domain concepts. When subnets are connected by RFC 1542-compliant routers, DHCP servers are not required on every subnet on the network. Note that DHCP servers can be administered remotely from a computer running under Windows NT Server that is DHCP- or WINS-enabled.
• Compile a list of requirements including:
  • Client support (numbers and kinds of systems to be supported)
  • Interoperability with existing systems (including your requirements for mission-critical accounting, personnel, and similar information systems)
  • Hardware support and related software compatibility (including routers, switches, and servers)
  • Network monitoring software, including Simple Network Management Protocol (SNMP) and other tools
• Isolate the areas of the network where processes must continue uninterrupted, and then target these areas for the last stages of implementation.
• Review the geographic and physical structure of the network to determine the best plan for defining logical subnets as segments of the intranet.
• Define the components in the new system that require testing, and then develop a phased plan for testing and adding components.

For example, the plan could define the order for types of computers to be phased in (including Windows NT servers and workstations, Microsoft RAS servers and clients, Windows for Workgroups computers, and MS-DOS clients).

• Create a pilot project for testing.
• Create a second test phase, including tuning the DHCP (and WINS) server-client configuration for efficiency.

This task can include determining strategies for backup servers and for partitioning the address pool at each server to be provided to local versus remote clients.

• Document all architecture and administration issues for network administrators.