Chapter 3 Dhcp Relay Configuration; Introduction To Dhcp Relay; Usage Of Dhcp Relay; Dhcp Relay Fundamentals - H3C S3600 Series Operation Manual

Operation Manual – DHCP
H3C S3600 Series Ethernet Switches-Release 1510

Chapter 3 DHCP Relay Configuration

3.1 Introduction to DHCP Relay

3.1.1 Usage of DHCP Relay

Since the packets are broadcasted in the process of obtaining IP addresses, DHCP is
only applicable to the situation that DHCP clients and DHCP servers are in the same
network segment, that is, you need to deploy at least one DHCP server for each
network segment, which is far from economical.
DHCP Relay is designed to address this problem. It enables DHCP clients in a subnet
to communicate with the DHCP server in another subnet so that the DHCP clients can
obtain IP addresses. In this case, the DHCP clients in multiple networks can use the
same DHCP server, which can decrease your cost and provide a centralized
administration.

3.1.2 DHCP Relay Fundamentals

Figure 3-1 illustrates a typical DHCP relay application.
DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client
DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client
Figure 3-1 Typical DHCP relay application
DHCP relays can transparently transmit broadcast packets of DHCP clients or servers
to the DHCP servers or clients in other network segments.
In the process of dynamic IP address assignment through the DHCP relay, the DHCP
client and DHCP server interoperate with each other in a similar way as they do without
the DHCP relay. The following sections only describe the forwarding process of the
DHCP relay. For the interaction process of the packets, see section 1.2.2 "Obtaining IP
Addresses Dynamically".
1) The DHCP client broadcasts the DHCP-DISCOVER packet.
DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client
Ethernet Ethernet Ethernet Ethernet Ethernet Ethernet Ethernet Ethernet
Sw itch ( DHCP rel Sw itch ( DHCP rel Sw itch ( DHCP rel Sw itch ( DHCP rel
DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client DHCP client
Chapter 3 DHCP Relay Configuration
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DHCP server DHCP server DHCP server DHCP server
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