Configuring Udp Helper - H3C S5100-SI Operation Manual

Table 1-1 List of default UDP ports
DNS (Domain Name System)
NetBIOS-DS (NetBIOS Datagram Service)
NetBIOS-NS (NetBIOS Name Service)
TACACS (Terminal Access Controller Access
Control System)
TFTP (Trivial File Transfer Protocol)
Time Service

Configuring UDP Helper

Follow these steps to configure UDP Helper:
To do...
Enter system view
Enable UDP Helper
Specify a UDP port number
Enter VLAN interface view
Specify the destination server
to which the UDP packets are
to be forwarded
You 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.
The 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.
You can specify up to 20 destination server addresses on a VLAN interface.
If 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.
Protocol
Use the command...
system-view
udp-helper enable
udp-helper port { port-number
| dns | netbios-ds | netbios-ns
| tacacs | tftp | time }
interface Vlan-interface
vlan-id
udp-helper server ip-address
UDP port number
53
138
137
49
69
37
—
Required
Disabled by default.
Optional
By default, the device enabled
with UDP Helper forwards the
broadcast packets containing
any of the six port numbers 53,
138, 137, 49, 69 and 37.
—
Required
No destination server is
specified by default.
1-2
Remarks