Configuring Udp Helper; Overview; Configuration Guidelines; Configuration Procedure - HP 6125XLG Layer 3-Ip Services Configuration Manual

Configuring UDP helper

Overview

UDP helper enables a device to convert received UDP broadcast packets into unicast packets and
forward them to a specific server. UDP helper is suitable for the scenario where hosts cannot obtain
configuration information or device names by broadcasting packets because the target server or host
resides on another broadcast domain.
Upon receiving a UDP broadcast packet (the destination address is 255.255.255.255 or a directed
broadcast address destined for the network directly connected to the receiving interface), UDP helper
matches the UDP destination port number of the packet against the configured UDP ports.
If a match is found, UDP helper modifies the destination IP address of the packet and sends the
•
packet to the specified destination server.
• If no match is found, UDP helper sends the packet to the upper layer protocol.
NOTE:
The term "interface" in this chapter collectively refers to VLAN interfaces and Layer 3 Ethernet interfaces.
You can set an Ethernet port as a Layer 3 interface by using the port link-mode route command (see
2—LAN Switching Configuration Guide

Configuration guidelines

Follow these guidelines when you configure UDP helper:
• By default, an interface does not receive directed broadcasts destined for the directly connected
network. To use UDP helper, execute the ip forward-broadcast command in interface view. For
more information about receiving directed broadcasts destined for the directly connected network,
see "Optimizing IP
Do not set UDP ports 67 and 68 for UDP helper because UDP helper cannot forward DHCP
•
broadcast packets.
• You can specify up to 256 UDP ports for UDP helper.
Specify destination servers on the interface that receives broadcast packets. You can specify up to
•
20 destination servers on an interface.

Configuration procedure

Step
1. Enter system view.
2. Enable UDP helper.
).
performance."
Command
system-view
udp-helper enable
129
Remarks
N/A
By default, UDP helper is
disabled.
Layer