H3C Technologies H3C S5120 Series Switches - Manual (Page 258)

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z You need to specify the ports connected to the authorized DHCP servers as trusted to ensure that
DHCP clients can obtain valid IP addresses. The trusted port and the port connected to the DHCP
client must be in the same VLAN.
z Currently, you can specify Layer 2 Ethernet interfaces and Layer 2 aggregate interfaces as trusted
ports. For details about aggregate interfaces, refer to Link Aggregation Configuration.
z If a Layer 2 Ethernet interface is added to an aggregation group, the DHCP snooping configuration
of the interface will not take effect. After the interface quits the aggregation group, the configuration
will be effective.
Configuring DHCP Snooping to Support Option 82
Prerequisites
You need to enable the DHCP snooping function before configuring DHCP snooping to support Option
82.
Configuring DHCP Snooping to Support Option 82
Follow these steps to configure DHCP snooping to support Option 82:
To do… Use the command… Remarks
Enter system view system-view —
Enter interface view
interface interface-type
interface-number
—
Enable DHCP snooping to support
Option 82
dhcp-snooping information enable
Required
Disabled by default.
Configure the handling strategy for
requesting messages containing
Option 82
dhcp-snooping information
strategy { drop | keep | replace } Optional
replace by default.
Configure the
padding format
for Option 82
dhcp-snooping information format
{ normal | verbose [ node-identifier
{ mac | sysname | user-defined
node-identifier } ] }
Optional
normal by default.
Configure
non-user-defined
Option 82
Configure the
code type for the
circuit ID
sub-option
dhcp-snooping information
circuit-id format-type { ascii | hex }
Optional
By default, the code
type depends on the
padding format of
Option 82. Each
field has its own
code type.
This code type
configuration
applies to
non-user-defined
Option 82 only.