Description: When the dhcp_snoop function is enabled, all address_binding disabled ports will act as DHCP server ports (the switch will learn IP addresses through DHCP server ports (by DHCP OFFER and DHCP ACK packets)).

The auto-learned IP-MAC binding entry will be mapped to a specific source port based on the MAC address learning function. This entry will be created as an ACL-mode binding entry for this specific port. Each entry is associated with a lease time. When the lease time expires, the expired entry will be removed from this port. The automatically learned binding entry can be moved from one port to another port if the DHCP snooping function has learned that the MAC address has moved to a different port.

Consider a case where DHCP snooping learns a binding entry, and the same IP-MAC binding entry has been statically configured. Suppose that the learned information is consistent with the statically configured entry, then the automatically learned entry will not be created. Suppose the entry is statically configured in ARP mode, since the automatically learned entry will be created in ACL mode, the entry will become ACL mode. Suppose the entry is statically configured on one port and the entry is automatically learned on another port, then both entries will exist.

When the dhcp_snoop function is disabled, all of the automatically learned binding entries will be removed.