(Optional) Configuring the Alarm Function forDiscarded DHCP Packets for Extending the IP Address Lease

By configuring the function described in this chapter, you can have an alarm generated when a specified number of Dynamic Host Configuration Protocol (DHCP) packets for extending the IP address lease are discarded.

Context

After DHCP request packet check is enabled, the device checks whether the source IP address, source MAC address, virtual local area network (VLAN) ID, and interface information carried in a received DHCP request packet match an entry in the DHCP snooping binding table. If no matching entry exists, the device considers the packet an attack packet and discards it. The device generates an alarm when the number of discarded DHCP packets for extending the IP address lease exceeds the threshold.

Configure the alarm function for discarded DHCP packets for extending the IP address lease in a VLAN, BD, or interface view.

Procedure

Configure the alarm function for discarded DHCP packets for extending the IP address lease in a VLAN view.
1. Run system-view
  The system view is displayed.
2. Run vlan vlan-id
  The VLAN view is displayed.
3. Run dhcp snooping alarm dhcp-request enable [ interface interface-type interface-number ]
  DHCP request packet check is enabled for the VLAN.
  
  By default, DHCP request packet check is disabled for a VLAN.
4. Run dhcp snooping alarm dhcp-request threshold threshold [ interface interface-type interface-number ]
  The alarm threshold for the number of discarded DHCP packets for extending the IP address lease is configured for the VLAN.
5. Run commit
  The configuration is committed.
Configure the alarm function for discarded DHCP packets for extending the IP address lease in a BD view.
1. Run system-view
  The system view is displayed.
2. Run bridge-domain bd-id
  The BD view is displayed.
3. Run dhcp snooping alarm dhcp-request enable
  Check for DHCP packets for extending the IP address lease is enabled.
4. Run dhcp snooping alarm dhcp-request threshold threshold-value
  An alarm threshold for the number of discarded DHCP packets for extending the IP address lease is configured.
5. Run commit
  The configuration is committed.
Configure the alarm function for discarded DHCP packets for extending the IP address lease in an interface view.
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The interface view is displayed.
3. Run dhcp snooping alarm dhcp-request enable
  DHCP request packet check is enabled for the interface.
4. Run dhcp snooping alarm dhcp-request threshold threshold-value
  The alarm threshold for the number of discarded DHCP packets for extending the IP address lease is configured for the interface.
5. Run commit
  The configuration is committed.