Huawei S Series Quick Configuration page 22

Configuring DHCP Snooping and IPSG
User devices can automatically obtain IP addresses after DHCP is configured. If a
user connects a small router to the intranet and enable the DHCP server on the router,
authorized intranet users may obtain IP addresses allocated by the small router and
cannot access the Internet. To prevent this problem, configure DHCP snooping.
Department A is used in the example below.
1 Enable DHCP snooping on ACC1.
<ACC1> system-view
[ACC1] dhcp enable
[ACC1] dhcp snooping enable
Enable DHCP snooping on Eth-Trunk1 that connects to the DHCP server and configure
2
it as a trusted interface.
[ACC1] interface eth-trunk 1
[ACC1-Eth-Trunk1] dhcp snooping enable
[ACC1-Eth-Trunk1] dhcp snooping trusted
interface.
[ACC1-Eth-Trunk1] quit
3 Enable DHCP snooping on interfaces that connect to user devices.
[ACC1] interface
[ACC1-Ethernet0/0/2] dhcp snooping enable
[ACC1-Ethernet0/0/2] quit
[ACC1] interface
[ACC1-Ethernet0/0/3] dhcp snooping enable
[ACC1-Ethernet0/0/3] quit
[ACC1] interface
[ACC1-Ethernet0/0/4] dhcp snooping enable
[ACC1-Ethernet0/0/4] quit
After the preceding configuration is complete, user devices in department A can
obtain IP addresses from only the authorized DHCP server, and will not use IP
addresses allocated by the small router.
//Enable DHCP.
//Enable DHCP snooping.
ethernet 0/0/2 //Configure the interface connecting to PC1.
ethernet 0/0/3 //Configure the interface connecting to PC2.
ethernet 0/0/4 //Configure the interface connecting to printers.
//Enable DHCP snooping.
//Configure Eth-Trunk1 as a trusted
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