Huawei Quidway S6500 Series Operation Manual page 106

Operation Manual - Network Protocol
Quidway S6500 Series Ethernet Switches
Chapter 5 DHCP Configuration
5.1 DHCP Overview
5.1.1 DHCP Fundamentals
This is a world where networks are ever-growing with configurations getting complex,
computers (such as laptop computers and wireless networks) are often moved, and the
available IP addresses are far from adequate for the ever-increasing number of
computers. In such a background dynamic host configuration protocol (DHCP) was
introduced. DHCP operates in Client/Server model, where the DHCP client dynamically
requests the DHCP server for configuration information and the DHCP server returns
the configuration information (an IP address for example) based on the adopted policy.
A typical DHCP application network usually comprises a DHCP server and multiple
clients such as PCs and laptop computers (see the following figure):
DHCP Client
DHCP Client
Figure 5-1 Typical networking application of DHCP Server
5.1.2 DHCP Relay
In the early days, the DHCP was only suitable for the case, when the DHCP Client and
DHCP Server locate on the same subnet, and could not work across the network
segments. If the early DHCP is used to dynamically configure the host, each subnet
should be equipped with a DHCP Server, which is obviously uneconomical. The
introduction of DHCP relay solves this difficulty. The DHCP relay serves as relay
between the DHCP Client and the DHCP Server located on different subnets. The
DHCP packets can be relayed to the destination DHCP Server (or Client) across
network segments. Thereby, the DHCP clients on different networks can use the same
DHCP Server. This is economical and convenient for centralized management.
DHCP Client
DHCP Server
LAN
DHCP Client
Huawei Technologies Proprietary
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Chapter 5 DHCP Configuration