H3C Technologies H3C S5560 Series Switches - Manual (Page 88)

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Step Command Remarks
3. Enable DHCP snooping to
support Option 82.
dhcp snooping information enable
By default, DHCP snooping
does not support Option
82.
4. (Optional.) Configure a
handling strategy for DHCP
requests that contain Option
82.
dhcp snooping information strategy { drop
| keep | replace } By default, the handling
strategy is replace.
5. (Optional.) Configure the
padding mode and
padding format for the
Circuit ID sub-option.
dhcp snooping information circuit-id
{ [ vlan vlan-id ] string circuit-id | { normal |
verbose [ node-identifier { mac | sysname
| user-defined node-identifier } ] } [ format
{ ascii | hex } ] }
By default, the padding
mode is normal and the
padding format is hex for
the Circuit ID sub-option.
6. (Optional.) Configure the
padding mode and
padding format for the
Remote ID sub-option.
dhcp snooping information remote-id
{ normal [ format { ascii | hex } ] | [ vlan
vlan-id ] string remote-id | sysname }
By default, the padding
mode is normal and the
padding format is hex for
the Remote ID sub-option.
Configuring DHCP snooping entry auto backup
The DHCP snooping entry auto backup function saves DHCP snooping entries to a backup file. The
DHCP snooping entries cannot survive a reboot. When the DHCP snooping device reboots, it
automatically downloads the entries from the backup file. The auto backup helps the security features
provide services if these features (such as IP source guard) must use DHCP snooping entries for user
authentication.
NOTE:
If you disable DHCP snooping with the undo dhcp snooping enable command, the device deletes all
DHCP snooping entries, including those stored in the backup file.
To configure DHCP snooping entry auto backup:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the DHCP snooping
device to back up DHCP
snooping entries to a file.
dhcp snooping binding database
filename { filename | url url
[ username username
[ password { cipher | simple }
key ] ] }
By default, the DHCP snooping
device does not back up DHCP
snooping entries.
With this command executed, the
DHCP snooping device backs up
DHCP snooping entries immediately
and runs auto backup.
This command automatically creates
the file if you specify a non-existent
file.