3Com Switch 7750 Configuration Guide Guide

676 CHAPTER 63: UDP-HELPER CONFIGURATION
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CAUTION:
■ You need to enable the UDP-Helper function before specifying a UDP-Helper
destination port.
■ The dns, netbios-ds, netbios-ns, tacacs, tftp, and time keywords refers to
the six default UDP ports. You can configure a default port to be a UDP-Helper
destination port by specifying the corresponding port number or the
corresponding keyword. For example, udp-helper port 53 and udp-helper
port dns specify the same port as a UDP-Helper destination port.
■ The display current-configuration command does not display the default
UDP ports that are configured to be UDP-Helper destination ports.
■ After UDP-Helper is disabled, all the configured UDP ports are cancelled,
including the default ports.
■ You can configure up to 40 UDP ports as UDP-Helper destination ports on a
device.
■ You can configure up to 20 destination servers on a VLAN interface.
■ If the destination server is configured on a VLAN interface, the UDP broadcast
packets received from the ports in the VLAN with specific UDP-Helper
destination ports are forwarded to the destination server configured on the
VLAN interface.
Displaying and
Debugging
UDP-Helper
After performing the above configurations, you can use the display command in
any view to display the information about the destination servers and the number
of the packets forwarded to each destination server. Verify the configuration by
checking the output information. You can use the reset command in user view to
clear statistics about packets forwarded by UDP-Helper. You can also use the
debugging command in user view to debug UDP-Helper.
Configure a UDP port as a
UDP-Helper destination port
udp-helper port {
port-number | dns |
netbios-ds | netbios-ns |
tacacs | tftp | time }
This operation is unnecessary
if the port is among the
default UDP ports listed in
Table 532.
With UDP-Helper enabled,
UDP broadcast packets
destined for the ports listed in
Table 532 are relayed by
default.
Enter VLAN interface view
interface vlan-interface
vlan-id
-
Configure the destination
server to which the matched
UDP broadcast packets are to
be forwarded
udp-helper server ip-address
Required
By default, no destination
server is configured
Table 533 Configure UDP-Helper
Operation Command Description