Reference Guide

ip unreachable
To view if ICMP unreachable messages are sent on the interface, use the show config command in
INTERFACE mode. If it is not listed in the show config command output, it is enabled. Only non-default
information is displayed in the
show config command output.
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
To configure Dell Networking OS to direct UDP broadcast, enable UDP helper and specify the UDP ports
for which traffic is forwarded. See Enabling UDP Helper
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 and Using the UDP Helper show Command
To view the interfaces and ports on which you enabled UDP helper, use the show ip udp-helper
command from EXEC Privilege mode.
Configuring a Broadcast Address
To configure a broadcast address, use the following command.
• Configure a broadcast address on an interface.
ip udp-broadcast-address
Examples of Configuring and Viewing a Broadcast Address
Dell(conf-if-vl-100)#ip udp-broadcast-address 1.1.255.255
Dell(conf-if-vl-100)#show config
426
IPv4 Routing