Users Guide

ARP Learning via ARP Request
The system learns via ARP requests only if the target IP specified in the packet matches the IP address of the receiving router
interface. This is the case when a host is attempting to resolve the gateway address.
If the target IP does not match the incoming interface, the packet is dropped. If there is an existing entry for the requesting
host, it is updated.
Figure 52. ARP Learning via ARP Request
When you enable ARP learning via gratuitous ARP, the system installs a new ARP entry, or updates an existing entry for all
received ARP requests.
Figure 53. ARP Learning via ARP Request with ARP Learning via Gratuitous ARP Enabled
Whether you enable or disable ARP learning via gratuitous ARP, the system does not look up the target IP. It only updates the
ARP entry for the Layer 3 interface with the source IP of the request.
Configuring ARP Retries
The number of ARP retries is user-configurable.
The default backoff interval remains at 20 seconds.
To set and display ARP retries, use the following commands.
• Set the number of ARP retries.
CONFIGURATION mode
IPv4 Routing 466