Dell Force10 MXL Blade - UDP Helper; Configuring UDP Helper; Important Points to Remember; Enabling UDP Helper

272 | IPv4 Routing
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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
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. Configurations
using this feature are described in Configurations Using UDP Helper.
Configuring UDP Helper
Configuring FTOS to direct UDP broadcast is a two-step process:
1. Enable UDP helper and specify the UDP ports for which traffic is forwarded (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 must 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 ip udp-helper udp-ports command (Figure 14-10).
Figure 14-10. Enabling UDP Helper
To view the interfaces and ports on which UDP helper is enabled, use the show ip udp-helper command from
EXEC Privilege mode (Figure 14-11).
FTOS(conf-if-te-1/1)#ip udp-helper udp-port 1000
FTOS(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