Configuring Udp Helper; Overview; Configuration Procedure - HP 830 Series Configuration Manual

Configuring UDP helper

UDP helper can be configured only on VLAN interfaces.

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, 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
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packet to the specified destination server.
If no match is found, UDP helper sends the packet to the upper layer protocol.
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Configuring UDP helper
UDP helper can be configured only on VLAN interfaces and Layer 3 Ethernet interfaces (including
•
subinterfaces).
Some devices do not receive directed broadcast destined to directly connected networks by default.
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To use UDP helper on these devices, you must execute the ip forward-broadcast command in system
view. For more information about reception and forwarding of directed broadcasts destined to
directly connected networks, see "Configuring IP performance optimization."
• UDP helper must not forward DHCP broadcast packets that use destination port 67 or 68. Therefore,
the UDP port numbers set with the udp-helper port command must not include 67 or 68.
You can specify a port number or the corresponding parameter for a UDP port to forward packets.
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For example, udp-helper port 53 and udp-helper port dns specify the same UDP port number.
The configuration of all UDP ports is removed if you disable UDP helper.
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You can specify up to 256 UDP ports for UDP helper.
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You can specify up to 20 destination servers on an interface.
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Configuration procedure

Step
1. Enter system view.
2. Enable UDP helper.
3. Specify a UDP port.
Command
system-view
udp-helper enable
udp-helper port { port-number | dns |
netbios-ds | netbios-ns | tacacs | tftp
| time }
90
Remarks
N/A
The default setting is disabled.
No UDP port is specified by
default.