Configuring Dhcp Snooping To Support Option 82 - HP 3600 v2 Series Configuration Manual

You can specify Layer 2 Ethernet interfaces and Layer 2 aggregate interfaces as trusted ports. For
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more information about aggregate interfaces, see Layer 2—LAN Switching Configuration Guide.
If a Layer 2 Ethernet interface is added to an aggregation group, the DHCP snooping configuration
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of the interface will not take effect. After the interface quits the aggregation group, the configuration
will be effective.
• DHCP snooping can work with basic QinQ or flexible QinQ. When receiving a packet without any
VLAN tag from the DHCP client to the DHCP server, the DHCP snooping device adds a VLAN tag
to the packet. If the packet has one VLAN tag, the device adds another VLAN tag to the packet and
records the two VLAN tags in a DHCP snooping entry. The newly added VLAN tag is the outer tag.
If the packet has two VLAN tags, the device directly forwards the packet to the DHCP server without
adding any tag.
If you need to add a new VLAN tag and meanwhile modify the original VLAN tag for the packet,
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DHCP snooping cannot work with flexible QinQ.
To configure DHCP snooping basic functions:
Step
1. Enter system view.
2. Enable DHCP snooping.
3. Enter Ethernet interface view.
4. Specify the port as a trusted port
that records the IP-to-MAC
bindings of clients.
5. Return to system view.
6. Enter interface view.
7. Specify the port as a trusted port
that does not record the IP-to-MAC
bindings of clients.

Configuring DHCP snooping to support Option 82

Follow these guidelines when configure DHCP snooping to support Option 82:
You can only enable 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 will not take effect. After the interface quits the aggregation
group, the configuration will be effective.
Option 82 support requires configuration on both the DHCP server and the device enabled with
•
DHCP snooping. See
If the handling strategy of the DHCP-snooping-enabled device is configured as replace, you need
•
to configure a padding format for Option 82. If the handling strategy is keep or drop, you need not
configure any padding format.
• If the Option 82 is padded with the device name, the device name must contain no spaces.
Otherwise, the DHCP-snooping device will drop the message. You can use the sysname command
Command
system-view
dhcp-snooping
interface interface-type
interface-number
dhcp-snooping trust
quit
interface interface-type
interface-number
dhcp-snooping trust
no-user-binding
"Configuring DHCP server" for DHCP server configuration of this kind.
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Remarks
N/A
Disabled by default.
The interface connects to the DHCP
server.
After DHCP snooping is enabled, a
port is an untrusted port by default.
N/A
The interface indirectly connects to the
DHCP client.
Optional.
After DHCP snooping is enabled, a
port is an untrusted port by default.