(Optional) Configuring the Alarm Function forDiscarded DHCP Packets with Incorrect CHADDR Fields

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 with incorrect client hardware address (CHADDR) fields are discarded.

Context

After CHADDR field check is enabled, the device checks whether the media access control (MAC) address in the CHADDR field of a received DHCP packet matches that in the frame header of the packet. If they match, the device considers the packet valid and forwards it. If they do not match, the device considers the packet an attack packet and discards it. The device generates an alarm when the number of discarded DHCP packets with incorrect CHADDR fields reaches the predetermined threshold.

Configure the alarm function for discarded DHCP packets with incorrect CHADDR fields in a VLAN, BD, or interface view.

Procedure

Configure the alarm function for discarded DHCP packets with incorrect CHADDR fields 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-chaddr enable [ interface interface-type interface-number ]
  CHADDR field check is enabled for the VLAN.
4. Run dhcp snooping alarm dhcp-chaddr threshold threshold [ interface interface-type interface-number ]
  The alarm threshold for discarded DHCP packets with incorrect CHADDR fields is configured for the VLAN.
5. Run commit
  The configuration is committed.
Configure the alarm function for discarded DHCP packets with incorrect CHADDR fields 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-chaddr enable
  CHADDR field check is enabled.
4. Run dhcp snooping alarm dhcp-chaddr threshold threshold
  The alarm threshold for discarded DHCP packets with incorrect CHADDR fields is configured.
5. Run commit
  The configuration is committed.
Configure the alarm function for discarded DHCP packets with incorrect CHADDR fields 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-chaddr enable
  CHADDR field check is enabled for the interface.
4. Run dhcp snooping alarm dhcp-chaddr threshold threshold-value
  The alarm threshold for discarded DHCP packets with incorrect CHADDR fields is configured for the interface.
5. Run commit
  The configuration is committed.