R3303-HP HSR6800 Routers Layer 3 - IP Services Configuration Guide

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To configure DHCP snooping basic functions:

Step Command Remarks

1. Enter system view.

system-view N/A

2. Enable DHCP snooping.

dhcp-snooping Disabled by default.

3. Enter Ethernet interface view.

interface interface-type

interface-number

The interface connects to the DHCP

server.

4. Specify the port as a trusted

port that records the

IP-to-MAC bindings of clients.

dhcp-snooping trust

After DHCP snooping is enabled, a

port is an untrusted port by default.

5. Return to system view.

quit N/A

6. Enter interface view.

interface interface-type

interface-number

The interface indirectly connects to

the DHCP client.

7. Specify the port as a trusted

port that does not record the

IP-to-MAC bindings of clients.

dhcp-snooping trust

no-user-binding

Optional.

After DHCP snooping is enabled, a

port is an untrusted port by default.

Configuring DHCP snooping to support Option 82

Follow these guidelines to configure DHCP snooping to support Option 82:

• You can only configure DHCP snooping to support Option 82 on Layer 2 Ethernet interfaces and

Layer 2 aggregate interfaces.

• If a Layer 2 Ethernet interface is added to an aggregation group, enabling DHCP snooping to

support Option 82 on the interface does not take effect. After the interface quits the aggregation

group, the configuration becomes effective.

• To support Option 82, perform configurations on both the DHCP server and the DHCP snooping

device. For this type of DHCP server configuration, see "Configuring the DHCP server."

• If the handling str

ategy of the DHCP-snooping device is configured as replace, configure a padding

format for Option 82. If the handling strategy is keep or drop, you do not need to configure any

padding format.

• If Option 82 contains the device name, the device name must contain no spaces. Otherwise, the

DHCP-snooping device 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 the DHCP snooping device receives a DHCP packet

with two VLAN tags, and the normal or 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:

Ste

Command

Remarks

1. Enter system view.

system-view N/A