3Com 4210G Series, Configuration Manual, Page: 288 / 1133

12-2
To do… Use the command… Remarks
Enter interface view
interface interface-type
interface-number
—
Specify the destination
server to which UDP packets
are to be forwarded
udp-helper server ip-address
Required
No destination server is specified
by default.
z
The UDP Helper enabled device cannot forward DHCP broadcast packets. That is to say, the
UDP port number cannot be set to 67 or 68.
z
For the
dns
,
netbios-ds
,
netbios-ns
,
tacacs
,
tftp
, and
time
keywords, you can specify port
numbers or the corresponding parameters. For example,
udp-helper port
53 and
udp-helper
port dns
specify the same UDP port number.
z
The configuration of all UDP ports is removed if you disable UDP Helper.
z
You can configure up to 256 UDP port numbers to enable the forwarding of packets with these
UDP port numbers.
z
You can configure up to 20 destination servers on an interface.
Displaying and Maintaining UDP Helper
To do… Use the command… Remarks
Displays the information of
forwarded UDP packets
display udp-helper server
[
interface interface-type
interface-number
]
Available in any view
Clear statistics about packets
forwarded
reset udp-helper packet
Available in user view
UDP Helper Configuration Examples
UDP Helper Configuration Example
Network requirements
On Switch A, configure UDP helper to forward broadcast packets (with UDP destination port number
55 and destination IP address 255.255.255.255 or 10.110.255.255 to the destination server
10.2.1.1/16.