H3C Technologies H3C S12500 Series Switches - Manual (Page 75)

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To configure basic DHCP snooping:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable DHCP snooping. dhcp snooping enable
By default, DHCP snooping is
disabled.
3. Enter interface view.
interface interface-type
interface-number
This interface is connected to the
DHCP server.
4. Specify the port as a trusted
port.
dhcp snooping trust
By default, all ports are untrusted
ports after DHCP snooping is
enabled.
5. Return to system view. quit N/A
6. Enter interface view.
interface interface-type
interface-number This interface is connected to the
DHCP client.
7. (Optional.) Enable recording
of DHCP snooping entries.
dhcp snooping binding record
By default, after DHCP snooping is
enabled, recording of DHCP
snooping entries is disabled.
74B
Configuring Option 82
Follow these guidelines when you configure Option 82:
• If you configure Option 82 on a Layer 2 Ethernet interface that has been added to an aggregation
group, the settings do not take effect unless the interface is removed from the aggregation group.
• To support Option 82, you must configure Option 82 on both the DHCP server and the DHCP
snooping device. For information about configuring Option 82 on the DHCP server, see "
720H
Enabling
handling of Option 82 ."
• If the handling strategy is configured as replace, you must configure a padding format for Option
82. If the handling strategy is keep or drop, there is no need to configure any padding format.
• If Option 82 contains the device name, the device name must contain no spaces. Otherwise, DHCP
snooping drops the message. You can use the sysname command to specify the device name. For
more information about this command, see Fundamentals Command Reference.
• If DHCP snooping and QinQ work together or DHCP snooping receives a DHCP packet with two
VLAN tags, and the verbose padding format is adopted for Option 82, DHCP snooping fills the
VLAN ID field of sub-option 1 with outer VLAN tag.inner VLAN tag. For example, if the outer VLAN
tag is 10 (a in hexadecimal) and the inner VLAN tag is 20 (14 in hexadecimal), the VLAN ID is
000a.0014.
To configure DHCP snooping to support Option 82:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view. interface interface-type interface-number N/A
3. Enable DHCP snooping to
support Option 82.
dhcp snooping information enable
By default, DHCP snooping
does not support Option
82.