ZyXEL Communications 4528F User Manual

 Chapter 43 ARP Learning

XGS-4526/4528F/4728F User’s Guide

other devices in the same network to update their ARP table with the new 
mapping information.

In Gratuitous-ARP learning mode, the Switch updates its ARP table with either an 
ARP reply or a gratuitous ARP request.

When the Switch is in ARP-Request learning mode, it updates the ARP table with 
both ARP replies, gratuitous ARP requests and ARP requests.

Therefore in the following example, the Switch can learn host A’s MAC address 
from the ARP request sent by host A. The Switch then forwards host B’s ICMP 
reply to host A right after getting host B’s MAC address and ICMP reply.