Reference Guide

IPv4 Routing | 355
Configurable ARP Retries
In FTOS versions prior to 8.3.1.0 the number of ARP retries is set to 5 and is not configurable. After 5
retries, FTOS backs off for 20 seconds before it sends a new request. Beginning with FTOS version
8.3.1.0, the number of ARP retries is configurable. The backoff interval remains at 20 seconds.
UDP Helper
UDP helper allows you to direct the forwarding IP/UDP broadcast traffic by creating special broadcast
addresses and rewriting the destination IP address of packets to match those addresses. Configurations
using this feature are described in the section Configurations Using UDP Helper.
Configuring UDP Helper
Configuring FTOS to direct UDP broadcast is a two-step process:
1. Enable UDP helper and specify the UDP ports for which traffic is forwarded. See Enabling UDP
Helper.
2. Configure a broadcast address on interfaces that will receive UDP broadcast traffic. See Configuring a
Broadcast Address.
Important Points to Remember about UDP Helper
• The existing command ip directed broadcast is rendered meaningless if UDP helper is enabled on the
same interface.
• The broadcast traffic rate should not exceed 200 packets per second when UDP helper is enabled.
• You may specify a maximum of 16 UDP ports.
• UDP helper is compatible with IP helper (
ip helper-address):
• UDP broadcast traffic with port number 67 or 68 are unicast to the DHCP server per the
ip
helper-address
configuration whether or not the UDP port list contains those ports.
• If the UDP port list contains ports 67 or 68, UDP broadcast traffic forwarded on those ports.
Task Command Syntax Command Mode
Set the number of ARP retries.
arp retries
number
Default: 5
Range: 5-20
CONFIGURATION
Display all ARP entries learned via gratuitous ARP.
show arp retries EXEC Privilege