3Com 7757 Configuration Manual page 633

DHCP-Snooping Option
82 Support
Configuration Example
Network diagram
Figure 163 DHCP-Snooping configuration
DHCP Client DHCP Client
DHCP Client DHCP Client
Configuration procedure
Perform the following configuration on the DHCP-Snooping-enabled Switch A.
# Enter system view.
<SW7750> system-view
# Enable the DHCP snooping function.
[SW7750] dhcp-snooping
# Enable DHCP-Snooping option 82.
[SW7750] dhcp-Snooping information enable
# Enter Ethernet 2/0/1 port view.
[SW7750] interface ethernet2/0/1
# Specify the port as a trusted port.
[SW7750-Ethernet2/0/1] dhcp-snooping trust
Network requirements
As shown in Figure 164, Ethernet 2/0/5 of the switch is connected to the DHCP
server, and Ethernet 2/0/1, Ethernet 2/0/2, and Ethernet 2/0/3 are respectively
connected to DHCP Client A, DHCP Client B, and DHCP Client C.
Enable DHCP snooping on the switch.
■
Specify Ethernet 2/0/5 on the switch as a trusted port for DHCP snooping.
■
Enable DHCP-snooping Option 82 support on the switch and set the remote ID
■
field in Option 82 to the system name of the switch. Set the circuit ID
sub-option to abcd in DHCP packets from VLAN 1 on Ethernet 2/0/3.
DHCP Snooping Configuration Example
Eth2/0/2 Eth2/0/1
Switch A
(DHCP Snooping)
DHCP Server
Internet
Switch B
(DHCP Relay)
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