Operation Manual – DHCP
H3C S3100 Series Ethernet Switches
Chapter 2 DHCP Snooping Configuration
2-1
Chapter 2 DHCP Snooping Configuration
2.1 Introduction
2.1.1 Introduction to DHCP Snooping
For the sake of security, the IP addresses used by online DHCP clients need to be
tracked for the administrator to verify the corresponding relationship between the IP
addresses the DHCP clients obtained from DHCP servers and the MAC addresses of
the DHCP clients.
z
Layer 3 switches can track DHCP client IP addresses through DHCP relay.
z
Layer 2 switches can track DHCP client IP addresses through the DHCP snooping
function, which listens DHCP broadcast packets.
Figure 2-1
illustrates a typical network diagram for DHCP snooping application, where
Switch A is an S3100 series Ethernet switch.
DHCP Client
Switch A
(DHCP Snooping)
DHCP Client
DHCP Client
DHCP Client
Switch B
(DHCP Relay)
Internet
Eth1/0/2
Eth1/0/1
DHCP Server
Figure 2-1
Typical network diagram for DHCP snooping application
On S3100-SI series Ethernet switches, DHCP snooping listens the DHCP-REQUEST
packets to retrieve the IP addresses the DHCP clients obtain from DHCP servers and
the MAC addresses of the DHCP clients.
On S3100-EI series Ethernet switches, DHCP snooping listens the DHCP-REQUEST
packets and DHCP-ACK packets to retrieve the IP addresses the DHCP clients obtain
from DHCP servers and the MAC addresses of the DHCP clients.