Sometimes, a host needs to forward broadcasts to obtain network configuration information or request
the names of other devices on the network. However, if the server or the device to be requested is
located 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. In
other words, UDP Helper functions as a relay agent that converts UDP broadcast packets into unicast
packets and forwards them to a specified destination server.
With UDP Helper enabled, the 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 not, the device sends the packet to the upper layer protocol for processing.
Configuration sample
# Enable UDP Helper.
<SwitchA> system-view
[SwitchA] udp-helper enable
# Enable the forwarding broadcast packets with the UDP destination port 55.
[SwitchA] udp-helper port 55
# Specify the destination server 10.2.1.1 on VLAN-interface 1.
[SwitchA] interface vlan-interface 1
[SwitchA-Vlan-interface1] ip address 10.110.1.1 16
[SwitchA-Vlan-interface1] udp-helper server 10.2.1.1
the names of other devices on the network. However, if the server or the device to be requested is
located 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. In
other words, UDP Helper functions as a relay agent that converts UDP broadcast packets into unicast
packets and forwards them to a specified destination server.
With UDP Helper enabled, the 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 not, the device sends the packet to the upper layer protocol for processing.
Configuration sample
# Enable UDP Helper.
<SwitchA> system-view
[SwitchA] udp-helper enable
# Enable the forwarding broadcast packets with the UDP destination port 55.
[SwitchA] udp-helper port 55
# Specify the destination server 10.2.1.1 on VLAN-interface 1.
[SwitchA] interface vlan-interface 1
[SwitchA-Vlan-interface1] ip address 10.110.1.1 16
[SwitchA-Vlan-interface1] udp-helper server 10.2.1.1
