Reference Guide

UDP Helper
User datagram protocol (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.
Configure 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. Refer to Enabling UDP Helper.
2. Configure a broadcast address on interfaces that will receive UDP broadcast traffic. Refer to Configuring a
Broadcast Address.
Important Points to Remember
• The existing ip directed broadcast command is rendered meaningless if you enable UDP helper on the
same interface.
• The broadcast traffic rate should not exceed 200 packets per second when you enable UDP helper.
• 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 dynamic host configuration protocol
(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 is forwarded on those ports.
Enabling UDP Helper
To enable UDP helper, use the following command.
• Enable UPD helper.
ip udp-helper udp-ports
Example of Enabling UDP Helper
FTOS(conf-if-gi-1/1)#ip udp-helper udp-port 1000
FTOS(conf-if-gi-1/1)#show config
!
interface GigabitEthernet 1/1
ip address 2.1.1.1/24
ip udp-helper udp-port 1000
no shutdown
To view the interfaces and ports on which you enabled UDP helper, use the show ip udp-helper command from
EXEC Privilege mode.
Example of the show ip udp-helper Command
FTOS#show ip udp-helper
--------------------------------------------------
Port UDP port list
--------------------------------------------------
Gi 1/1 1000
406