Deployment Guide

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
You can configure the number of ARP retries.
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
arp retries number
The default is 5.
The range is from 1 to 20.
● Set the exponential timer for resending unresolved ARPs.
CONFIGURATION mode
arp backoff-time
The default is 30.
The range is from 1 to 3600.
● Display all ARP entries learned via gratuitous ARP.
EXEC Privilege mode
show arp retries
ICMP
For diagnostics, the internet control message protocol (ICMP) provides routing information to end stations by choosing the best
route (ICMP redirect messages) or determining if a router is reachable (ICMP Echo or Echo Reply).
ICMP error messages inform the router of problems in a particular packet. These messages are sent only on unicast traffic.
Configuration Tasks for ICMP
The following lists the configuration tasks for ICMP.
● Enabling ICMP Unreachable Messages
For a complete listing of all commands related to ICMP, refer to the Dell EMC Networking OS Command Line Reference Guide.
Enabling ICMP Unreachable Messages
By default, ICMP unreachable messages are disabled.
When enabled, ICMP unreachable messages are created and sent out all interfaces.
To disable and re-enable ICMP unreachable messages, use the following commands.
● To disable ICMP unreachable messages.
INTERFACE mode
no ip unreachable
● Set Dell EMC Networking OS to create and send ICMP unreachable messages on the interface.
INTERFACE mode
ip unreachable
IPv4 Routing
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