3Com WX3000 operation manual Configuring UDP Helper

Protocol	UDP port number
Time Service	37

Configuring UDP Helper

Follow these steps to configure UDP Helper:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Enable UDP Helper	udp-helper enable	Required
		Disabled by default.
		Optional
	udp-helper port { port-number	By default, the device enabled
Specify a UDP port number		with UDP Helper forwards the
	dns netbios-ds netbios-ns
	tacacs tftp time }	broadcast packets containing
		any of the six port numbers 53,
		138, 137, 49, 69 and 37.
Enter VLAN interface view	interface Vlan-interface	—
	vlan-id
Specify the destination server		Required
to which the UDP packets are	udp-helper server ip-address	No destination server is
to be forwarded		specified by default.

zYou need to enable UDP Helper before specifying any UDP port to match UDP broadcasts; otherwise, the configuration fails. When the UDP helper function is disabled, all configured UDP ports are disabled, including the default ports.

zThe dns, netbios-ds, netbios-ns, tacacs, tftp, and time keywords correspond to the six default ports. You can configure the default ports by specifying port numbers or the corresponding parameters. For example, udp-helper port 53 and udp-helper port dns specify the same port.

zYou can specify up to 20 destination server addresses on a VLAN interface.

zIf UDP Helper is enabled after a destination server is configured for a VLAN interface, the broadcasts from interfaces belonging to the VLAN and having a matching UDP port will be unicast to the destination server.

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