Concept Guide

Table Of Contents
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
DellEMC(conf-if-te-1/1)#ip udp-helper udp-port 1000
DellEMC(conf-if-te-1/1)#show config
!
interface TenGigabitEthernet 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.
DellEMC#show ip udp-helper
--------------------------------------------------
Port UDP port list
--------------------------------------------------
te 1/1 1000
Configuring a Broadcast Address
To configure a broadcast address, use the following command.
Configure a broadcast address on an interface.
ip udp-broadcast-address
DellEMC(conf-if-vl-100)#ip udp-broadcast-address 1.1.255.255
DellEMC(conf-if-vl-100)#show config
!
interface Vlan 100
ip address 1.1.0.1/24
ip udp-broadcast-address 1.1.255.255
untagged TenGigabitEthernet 1/2
no shutdown
To view the configured broadcast address for an interface, use show interfaces command.
DellEMC#show interfaces vlan 100
Vlan 100 is up, line protocol is down
Address is 00:01:e8:0d:b9:7a, Current address is 00:01:e8:0d:b9:7a
Interface index is 1107787876
Internet address is 1.1.0.1/24
IP UDP-Broadcast address is 1.1.255.255
MTU 1554 bytes, IP MTU 1500 bytes
LineSpeed auto
ARP type: ARPA, ARP Timeout 04:00:00
Last clearing of "show interface" counters 00:07:44
Queueing strategy: fifo
Input Statistics:
0 packets, 0 bytes
Time since last interface status change: 00:07:44
IPv4 Routing
433