Overview

DHCP snooping works between the DHCP client and server, or between the DHCP client and DHCP relay agent. It guarantees that DHCP clients obtain IP addresses from authorized DHCP servers. Also, it records IP-to-MAC bindings of DHCP clients (called DHCP snooping entries) for security purposes.

DHCP snooping does not work between the DHCP server and DHCP relay agent.

DHCP snooping defines trusted and untrusted ports to make sure clients obtain IP addresses only from authorized DHCP servers.

DHCP snooping reads DHCP-ACK messages received from trusted ports and DHCP-REQUEST messages to create DHCP snooping entries. A DHCP snooping entry includes the MAC and IP addresses of a client, the port that connects to the DHCP client, and the VLAN.

The following features need to use DHCP snooping entries: