Chapter 2 Dhcp Snooping Configuration; Introduction; Introduction To Dhcp Snooping - H3C S3100 8C SI Operation Manual

Operation Manual – DHCP
H3C S3100 Series Ethernet Switches

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.
Layer 3 switches can track DHCP client IP addresses through DHCP relay.
Layer 2 switches can track DHCP client IP addresses through the DHCP snooping
function, which listens DHCP broadcast packets.
Figure 2-1
Switch A is an S3100 series Ethernet switch.
DHCP Client
DHCP Client
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.
illustrates a typical network diagram for DHCP snooping application, where
DHCP Client
Eth1/0/1
(DHCP Snooping)
DHCP Client
Chapter 2 DHCP Snooping Configuration
DHCP Server
Eth1/0/2
Switch A
(DHCP Relay)
2-1
Internet
Switch B