Operation Manual – UDP Helper
H3C S5600 Series Ethernet Switches
Chapter 1 UDP Helper Configuration
1-3
Note:
z
On an S5600 Series Ethernet Switch, the reception of directed broadcast packets to
a directly connected network is disabled by default. As a result, UDP Helper is
available only when the
ip forward-broadcast
command is configured in system
view. For details about the
ip forward-broadcast
command, refer to the
IP Address
and Performance
part of this manual.
z
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.
z
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.
z
You can specify up to 20 destination server addresses on a VLAN interface.
z
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.
1.3 Displaying and Maintaining UDP Helper
To do…
Use the command…
Remarks
Display the UDP broadcast relay
forwarding information of a
specified VLAN interface on the
switch
display udp-helper
server
[
interface
vlan-interface
vlan-id
]
Available in any
view
Clear statistics about packets
forwarded by UDP Helper
reset udp-helper packet
Available in user
view
1.4 UDP Helper Configuration Example
1.4.1 Cross-Network Computer Search Through UDP Helper
I. Network requirements
PC A resides on network segment 192.168.1.0/24 and PC B on 192.168.10.0/24; they
are connected through Switch A and are routable to each other. It is required to
configure UDP Helper on the switch, so that PC A can find PC B through computer
search. (Broadcasts with UDP port 137 are used for searching.)