Administrator Guide

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
DellEMC(conf-if-gi-1/1)#ip udp-helper udp-port 1000
DellEMC(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.
DellEMC#show ip udp-helper
--------------------------------------------------
Port UDP port list
--------------------------------------------------
Gi 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 GigabitEthernet 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
IPv4 Routing
355