Users Guide

Enabling ICMP Unreachable Messages
By default, ICMP unreachable messages are disabled.
When enabled, ICMP unreachable messages are created and sent out all interfaces.
To disable and re-enable ICMP unreachable messages, use the following commands.
• To disable ICMP unreachable messages.
INTERFACE mode
no ip unreachable
• Set Dell Networking OS to create and send ICMP unreachable messages on the interface.
INTERFACE mode
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.
IPv4 Routing 469