H3C Technologies H3C S10500 Series Switches - Manual (Page 108)

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UDP Helper configuration
NOTE:
The term interface in this document refers to Layer 3 interfaces, including VLAN interfaces and route-mode
(or Layer 3) Ethernet ports. You can set an Ethernet port to operate in route mode by using the port
link-mode route command (see Layer 2—LAN Switching Configuration Guide).
Introduction to UDP Helper
UDP Helper functions as a relay agent that converts UDP broadcast packets into unicast packets and
forwards them to a specified destination server. This is helpful when a host cannot obtain network
configuration information or request device names through broadcasting because the server or host to be
requested is located on another broadcast domain.
With UDP Helper enabled, a device decides whether to forward a received UDP broadcast packet
according to the UDP destination port number of the packet.
• If the destination port number of the packet matches the one pre-configured on the device, the
device modifies the destination IP address in the IP header, and then sends the packet to the
specified destination server.
• If the destination port number of the packet does not match the one pre-configured on the device,
the device sends the packet to the upper layer protocol for processing.
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.
Enable the forwarding of packets
with the specified UDP destination
port number(s)
udp-helper port { port-number | dns |
netbios-ds | netbios-ns | tacacs | tftp
| time }
Required
No UDP port number is specified
by default.
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.