Configuring DHCP Binding Table Update

The Dynamic Host Configuration Protocol (DHCP) binding table update function contains the client online status detection function and the DHCP snooping binding entry deletion function.

Usage Scenario

If a client obtains an IP address and goes offline abnormally, the client cannot release the IP address by sending a DHCP release packet. To resolve this problem, you can configure client online status detection. After client online status detection is enabled, the system uses Address Resolution Protocol (ARP) to detect a client periodically. If the system cannot detect the client for specified times, the system will delete the DHCP snooping binding entry for the client. The system also sends a release packet to the DHCP server to release the client's IP address.

This function can only be deployed on Layer 3 devices.
A DHCP snooping binding entry can be deleted manually if required. You can configure the client to send a release packet to the DHCP server to release the client's IP address.

This function dynamically maintains the DHCP snooping binding table. You can delete DHCP snooping binding entries based on virtual local area networks (VLANs), interfaces, or IP addresses.

Procedure

Configure client online status detection.
1. Run system-view
  The system view is displayed.
2. Run arp dhcp-snooping-detect enable
  Client online status detection is enabled.
3. Run commit
  The configuration is committed.
Configure dynamic DHCP snooping binding entry deletion.
1. Run system-view
  The system view is displayed.
2. Run reset dhcp snooping bind-table [ vlan vlan-id [ interface interface-type interface-number ] | bridge-domain bd-id | interface interface-type interface-number | vpn-instance vpn-instance-name | public-net | ip-address ip-address [ interface interface-type interface-number ] | vsi vsi-name ] [ release ]
  The dynamic DHCP snooping binding entry is deleted.
  
  Using the release parameter, you can configure the client to send a release packet to the DHCP server to release the client's IP address.
Configure static DHCP snooping binding entry deletion.
1. Run system-view
  The system view is displayed.
2. Run undo dhcp snooping bind-table static [ vlan vlan-id [ interface interface-type interface-number ] | interface interface-type interface-number | vsi vsi-name | ip-address ip-address | bridge-domain bd-id ]
  The static DHCP snooping binding entry is deleted.
3. Run commit
  The configuration is committed.