Dhcp Snooping Typical Application - Planet WGSW-52040 Configuration Manual

ip dhcp snooping information
option subscriber-id {standard |
<circuit-id>}
no ip dhcp snooping information
option subscriber-id
Command
Globe mode
ip dhcp snooping information
option allow-untrusted (replace|)
no ip dhcp snooping information
option allow-untrusted (replace|)

36.3 DHCP Snooping Typical Application

As showed in the above chart, Mac-AA device is the normal user, connected to the non-trusted
port 1/1 of the switch. It operates via DHCP Client, IP 1.1.1.5; DHCP Server and GateWay are
connected to the trusted ports 1/11 and 1/12 of the switch; the malicious user Mac-BB is
connected to the non-trusted port 1/10, trying to fake a DHCP Server （ by sending DHCPACK） .
Set the suboption1 (circuit ID option) content of
option 82 added by DHCP request packets (they
are received by the port). The no command sets
the additive suboption1 (circuit ID option) format
of option 82 as standard.
Explanation
This command is used to set that allow
untrusted ports of DHCP snooping to receive
DHCP packets with option82 option. When the
"replace" is setting, the potion82 option is
allowed to replace. When disabling this
command, all untrusted ports will drop DHCP
packets with option82 option.
Figure 36-1: Sketch Map of TRUNK
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