
Operation Manual - Management VLAN
Quidway S5600 Series Ethernet Switches-Release 1510
Chapter 2 DHCP/BOOTP Client Configuration
Huawei Technologies Proprietary
2-2
DHCP Client
DHCP Server
DHCP Client
DHCP Client
DHCP Client
DHCP Server
DHCP Server
DHCP_D
iscover
DHCP_R
equest
DHC
P_Of
fer
DHC
P_AC
K
DHCP_R
enew
DHC
P_AC
K
r
DHCP_D
iscover
DHCP_R
equest
DHC
P_Of
fer
DHC
P_AC
K
DHCP_R
enew
DHC
P_AC
K
DHCP Client
DHCP Server
DHCP Client
DHCP Client
DHCP Client
DHCP Server
DHCP Server
DHCP_D
iscover
DHCP_R
equest
DHC
P_Of
fer
DHC
P_AC
K
DHCP_R
enew
DHC
P_AC
K
r
DHCP Client
DHCP Server
DHCP Client
DHCP Client
DHCP Client
DHCP Server
DHCP Server
DHCP_D
iscover
DHCP_R
equest
DHC
P_Of
fer
DHC
P_AC
K
DHCP_R
enew
DHC
P_AC
K
r
DHCP_D
iscover
DHCP_R
equest
DHC
P_Of
fer
DHC
P_AC
K
DHCP_R
enew
DHC
P_AC
K
Figure 2-2
Interaction between a DHCP client and a DHCP server
To obtain valid dynamic IP addresses, a DHCP client exchanges different information
with the DHCP server in different phases. Usually, the following three modes are
involved:
1)
The DHCP client accesses the network for the first time
In this case, the DHCP client goes through the following four phases to establish
connections with the DHCP server.
z
Discovery. The DHCP client discovers a DHCP server by broadcasting
DHCP_Discover packets in the network. Only the DHCP servers respond to this
type of packets.
z
Offer. Upon receiving DHCP_Discover packets, a DHCP server select an
available IP address from an address pool and sends a DHCP_Offer packet that
carries the selected IP address and other configuration information to the DHCP
client. The DHCP client only accepts the first-arrived DHCP_Offer packet (if there
are many DHCP servers), and broadcasts a DHCP_Request packet to each
DHCP server. The packet contains the IP address carried by the DHCP_Offer
packet.