Reference Guide

IPv4 Routing | 391
2. Configure a broadcast address on interfaces that will receive UDP broadcast traffic. See Configuring a
Broadcast Address on page 391.
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.
Enabling UDP Helper
Enable UPD helper using the command ip udp-helper udp-ports, as shown in Figure 18-10.
Figure 18-10. Enabling UDP Helper
View the interfaces and ports on which UDP helper is enabled using the command show ip udp-helper
from EXEC Privilege mode, as shown in Figure 18-11.
Figure 18-11. Viewing the UDP Broadcast Configuration
Configuring a Broadcast Address
Configure a broadcast address on an interface using the command ip udp-broadcast-address, as shown in
Figure 18-12.
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
FTOS#show ip udp-helper
--------------------------------------------------
Port UDP port list
--------------------------------------------------
Gi 1/1 1000