828 CHAPTER 60: DHCP S NOOPING CONFIGURATIONConfiguring DHCPSnooping BasicFunctionsFollow these steps to configure DHCP snooping basic functions:n ■ You need to specify the ports connected to the valid DHCP servers as trusted toensure that DHCP clients can obtain valid IP addresses. The trusted port and theport connected to the DHCP client must be in the same VLAN.■ You are not recommended to configure both the DHCP snooping and selectiveQ-in-Q function on the switch, which may result in the DHCP snooping tofunction abnormally.Configuring DHCPSnooping to SupportOption 82Prerequisites You need to enable the DHCP Snooping function before configuring DHCPSnooping to support Option 82.Configuring DHCPSnooping to SupportOption 82Follow these steps to configure DHCP snooping to support Option 82:n ■ To support Option 82, it is required to perform related configuration on boththe DHCP server and the device enabled with DHCP Snooping. Refer to“Configuring the Handling Mode for Option 82” on page 808 for DHCP serverconfiguration of this kind.To do… Use the command… RemarksEnter system view system-view -Enable DHCP snooping dhcp-snooping RequiredDisabled by default.Enter Ethernet port view interface interface-typeinterface-number-Specify the port as trusted dhcp-snooping trust[ no-user-binding ]RequiredUntrusted by default.To do… Use the command… RemarksEnter system view system-view -Enter Ethernet port view interface interface-typeinterface-number-Enable DHCP Snooping tosupport Option 82dhcp-snooping informationenableRequiredDisabled by default.Configure the handlingstrategy for requestingmessages containing Option82dhcp-snooping informationstrategy { drop | keep |replace }Optionalreplace by default.Configure the padding formatfor Option 82dhcp-snooping informationformat { normal | verbose[ node-identifier { mac |sysname | user-definednode-identifier } ] }Optionalnormal by default.
