3Com Switch 8800 Advanced Software V5 Configuration Guide

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DHCP SERVER CONFIGURATION
When configuring the DHCP server, go to these sections for information you are
interested in:
■ “Introduction to DHCP Server” on page 721
■ “DHCP Server Configuration Task List” on page 723
■ “Enabling DHCP” on page 723
■ “Enabling the DHCP Server on an Interface” on page 723
■ “Configuring an Address Pool for the DHCP Server” on page 724
■ “Configuring the DHCP Server Security Functions” on page 730
■ “Enabling the DHCP Server to Support Option 82” on page 731
■ “Displaying and Maintaining the DHCP Server” on page 732
■ “DHCP Server Configuration Example” on page 732
■ “Troubleshooting DHCP Server Configuration” on page 734
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The DHCP server configuration is supported only on VLAN interfaces.
Introduction to DHCP
Server
Application
Environment
The DHCP server is well suited to the network where:
■ It is hard to implement manual configuration and centralized management.
■ The hosts are more than the assignable IP addresses and it is impossible to
assign a fixed IP address to each host. For example, an ISP limits the number of
hosts to access the Internet at a time, so lots of hosts need to acquire IP
addresses dynamically.
■ A few hosts need fixed IP addresses.
DHCP Address Pool In response to a client’s request, the DHCP server selects an idle IP address from an
address pool and sends it together with other parameters such as lease and DNS
server address to the client.
The address pool database is organized as a tree. The root of the tree is the
address pool for natural networks, branches are address pools for subnets, and
leaves are addresses statically bound to clients. For the same level address pools, a
previously configured pool has a higher selection priority than a new one.