mac

318
option 82 (Circuit ID option) is standard vlan name plus physical port name, like
vlan1+ethernet1/12. That of option2 in option 82 (remote ID option) is CPU MAC of the
switch, like 00030f023301. If a DHCP request message with option 82 options is received,
DHCP Snooping will replace those options in the message with its own. If a DHCP reply
message with option 82 options is received, DHCP Snooping will dump those options in
the message and forward it.
Examples: Enable option 82 function of DHCP Snooping on the switch.
Switch(config)#ip dhcp snooping enable
Switch(config)# ip dhcp snooping binding enable
Switch(config)# ip dhcp snooping information enable
19.17 ip dhcp snooping information option
allow-untrusted
Command: ip dhcp snooping information option allow-untrusted
no ip dhcp snooping information option allow-untrusted
Function: This command is used to set that allow untrusted ports of DHCP snooping to
receive DHCP packets with option82 option. When disabling this command, all untrusted
ports will drop DHCP packets with option82 option.
Parameter: None.
Command Mode: Global Mode
Default: Drop DHCP packets with option82 option received by untrusted ports.
Usage Guide: Usually the switch with DHCP snooping function connects the terminal
user directly, so close allow-untrusted by default to avoid option82 option added by user
privately. Please set uplink port as trust port when enabling the uplink of DHCP snooping
function.
Example: Enable the function that receives DHCP packets with option82.
Switch(config)#ip dhcp snooping information option allow-untrusted
19.18 ip dhcp snooping information option delimiter
Command: ip dhcp snooping information option delimiter [colon | dot | slash |
space]
no ip dhcp snooping information option delimiter
Function: Set the delimiter of each parameter for suboption of option82 in global mode,
no command restores the delimiter as slash.