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Step
2.
Enable DHCP snooping.
3.
Enter interface view.
4.
Specify the port as a trusted
port.
5.
Return to system view.
6.
Enter interface view.
7.
(Optional.) Enable the
recording of DHCP snooping
entries.
Configuring Option 82
Restrictions and guidelines
Follow these guidelines when you configure Option 82:
•
The Option 82 configuration on a Layer 2 Ethernet interface that has been added to an
aggregation group does not take effect unless the interface leaves 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
"Enabling handling of Option
•
If the handling strategy is replace, configure a padding mode and padding format for Option 82.
If the handling strategy is keep or drop, you do not need to configure any padding mode or
padding format for Option 82. The settings do not take effect even if you configure them.
•
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.
•
DHCP snooping uses "outer VLAN tag.inner VLAN tag" to fill the VLAN ID field of sub-option 1
in verbose padding format if either of the following conditions exists:
DHCP snooping and QinQ work together.
DHCP snooping receives a DHCP packet with two VLAN tags.
For example, if the outer VLAN tag is 10 and the inner VLAN tag is 20, the VLAN ID field is
000a.0014. The hexadecimal digit a represents the outer VLAN tag 10, and the hexadecimal
digit 14 represents the inner VLAN tag 20.
•
The device name (sysname) must not include spaces if it is configured as the padding content
for sub-option 1. Otherwise, the DHCP snooping device will fail to add or replace Option 82.
Procedure
To configure DHCP snooping to support Option 82:
Step
1.
Enter system view.
2.
Enter interface view.
Command
dhcp snooping enable
interface interface-type
interface-number
dhcp snooping trust
quit
interface interface-type
interface-number
dhcp snooping binding
record
82."
Command
system-view
interface interface-type interface-number
160
Remarks
By default, DHCP snooping is
disabled.
This interface must connect to the
DHCP server.
By default, all ports are untrusted
ports after DHCP snooping is
enabled.
N/A
This interface must connect to the
DHCP client.
By default, the recording of DHCP
snooping entries is disabled.
Remarks
N/A
N/A
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Troubleshooting
