Operation Manual – DHCP-Snooping
Quidway S3100 Series Ethernet Switches
Chapter 1 DHCP-Snooping Configuration
Huawei Technologies Proprietary
1-2
DHCP Client
DHCP Server
DHCP Client
DHCP Client
DHCP Client
DHCP Server
DHCP_D
iscover
DHCP_R
equest
DHC
P_Of
fer
DHC
P_AC
K
DHCP_R
enew
DHC
P_AC
K
DHCP Client
DHCP Client
DHCP Server
DHCP Server
DHCP Client
DHCP Client
DHCP Client
DHCP Client
DHCP Client
DHCP Client
DHCP Server
DHCP Server
DHCP Server
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
Figure 1-2
The interaction between a DHCP client and a DHCP server
With the DHCP-snooping function enabled, a switch acquires the IP address which a
host obtains from the DHCP server and its MAC address in the following two ways:
z
Listening DHCP_ACK packets
z
Listening DHCP_REQUEST packets
1.1.2 DHCP-Snooping Entry Updating
I. DHCP-Snooping table
Upon the DHCP-Snooping function is enabled on an S3100 series switch, the switch
creates a DHCP-Snooping table to store the information obtained from the DHCP
server, including User IP addresses and the corresponding MAC addresses. Each IP
address-MAC address pair in a DHCP-Snooping table forms a table entry (referred to
as a DHCP-Snooping entry).
Note that a DHCP-Snooping entry does not age automatically.