1-11 UDP Helper ConfigurationWhen configuring UDP Helper, go to these sections for information you are interested in:z Introduction to UDP Helperz Configuring UDP Helperz Displaying and Maintaining UDP Helperz UDP Helper Configuration ExamplesUDP Helper can be currently configured on VLAN interfaces only.Introduction to UDP HelperSometimes, a host needs to forward broadcasts to obtain network configuration information or requestthe names of other devices on the network. However, if the server or the device to be requested islocated in another broadcast domain, the host cannot obtain such information through broadcast.To solve this problem, the device provides the UDP Helper function to relay specified UDP packets. Inother words, UDP Helper functions as a relay agent that converts UDP broadcast packets into unicastpackets and forwards them to a specified destination server.With UDP Helper enabled, the device decides whether to forward a received UDP broadcast packetaccording to the UDP destination port number of the packet.z If the destination port number of the packet matches the one pre-configured on the device, thedevice modifies the destination IP address in the IP header, and then sends the packet to thespecified destination server.z If not, the device sends the packet to the upper layer protocol for processing.Configuring UDP HelperFollow these steps to configure UDP Helper:To do… Use the command… RemarksEnter system view system-view —Enable UDP Helper udp-helper enable RequiredDisabled by default.Enable the forwarding ofpackets with the specifiedUDP destination portnumber(s)udp-helper port { port-number| dns | netbios-ds | netbios-ns| tacacs | tftp | time }RequiredNo UDP port number is specifiedby default.
