3Com Switch 7750 Configuration Guide Guide

53
DHCP OVERVIEW
Introduction to DHCP With networks getting larger in size and more complicated in structure, lack of
available IP addresses becomes the common situation the network administrators
have to face, and network configuration becomes a tough task for the network
administrators. With the emerging of wireless networks and the using of laptops,
the position change of hosts and frequent change of IP addresses also require new
technology. Dynamic host configuration protocol (DHCP) is developed in this
background.
DHCP adopts a client/server model, where DHCP clients send requests to DHCP
servers for configuration parameters; and the DHCP servers return the
corresponding configuration information such as IP addresses to configure IP
addresses dynamically.
A typical DHCP application includes one DHCP server and multiple clients (such as
PCs and laptops), as shown in
Figure 144.
Figure 144 Typical DHCP application
DHCP IP Address
Assignment
IP Address Assignment
Policy
Currently, DHCP provides the following three IP address assignment policies to
meet the requirements of different clients:
■ Manual assignment. The administrator statically binds IP addresses to few
clients with special uses (such as WWW server). Then the DHCP server assigns
these fixed IP addresses to the clients.
■ Automatic assignment. The DHCP server assigns IP addresses to DHCP clients.
The IP addresses will be occupied by the DHCP clients permanently.
LAN
DHCP Server
DHCP Client DHCP Client
DHCP Client DHCP Client