Method, apparatus, device and system for generating DHCP snooping binding table

A system for generating a Dynamic Host Configuration Protocol (DHCP) snooping binding table, wherein the system comprises:

• a network device;
• and
• a DHCP server in communication with the network device,
• wherein the network device is configured to:
• send a DHCP inform packet to the DHCP server, wherein the DHCP Inform packet requests an internet protocol (IP) address and a media access control (MAC) address of a DHCP client;
• receive, from the DHCP server, a response packet responsive to the DHCP Inform packet;
• extract the IP address and the MAC address of the DHCP client from the response packet;
• and
• generate a DHCP snooping binding entry based on the IP address the MAC address, VLAN number, and ingress port number of the of the DHCP client, obtaining a virtual local area network (VLAN) number and an ingress port number of the DHCP client from a MAC table using the MAC address;
• and
• wherein the DHCP server is configured to receive the DHCP Inform packet and construct the response packet responsive to the DHCP Inform packet,
• wherein the response packet comprises the IP address and the MAC address of the DHCP client,
• wherein the DHCP Inform packet comprises a subnetwork address and a corresponding subnetwork mask,
• wherein the subnetwork address and the subnetwork mask identify a subnetwork being monitored by DHCP snooping and by the network device,
• wherein the IP address and the MAC address of the DHCP client in the response packet is within the subnetwork identified by the subnetwork address and the subnetwork mask, and
• wherein the DHCP client is a client that has established a connection with the DHCP server before DHCP snooping is enabled.

A network device comprising a processor and a network interface, wherein the processor is configured to:

• send a Dynamic Host Configuration Protocol (DHCP) Inform packet to a DHCP server, wherein the DHCP Inform packetrequests an Internet Protocol (IP) address and a Media Access Control (MAC) address of a DHCP client using the network interface;
• receive a response packet responsive to the DHCP Inform packet from the DHCP server by using the network interface;
• extract the IP address and the MAC address of the DHCP client from the response packet;
• obtain a virtual local area network (VLAN) number and an ingress port number of the DHCP client from a MAC table using the MAC address;
• and
• generate a DHCP snooping binding entry based on the IP address, MAC address, VLAN number, and ingress port number of the DHCP client,
• wherein the DHCP Inform packet comprises a subnetwork address and a corresponding subnetwork mask, wherein the subnetwork address and the subnetwork mask identify a subnetwork being monitored by DHCP snooping and by the network device, wherein the IP address and the MAC address of the DHCP client in the response packet is within the subnetwork identified by the subnetwork address and the subnetwork mask, and wherein the DHCP client is a client that has established a connection with the DHCP server before DHCP snooping is enabled.