Configuring UDP helper to convert broadcast to multicast

You can configure UDP helper to convert broadcast packets with specific UDP port numbers to multicast packets.

Upon receiving a UDP broadcast packet, UDP helper uses the configured UDP ports to match the UDP destination port number of the packet.

• If a match is found, UDP helper duplicates the packet and modifies the destination IP address of the copy to the configured multicast address. Then UDP helper forwards the packet to the multicast group.

• If no match is found, UDP helper does not process the packet.

1. Enter system view.

   system-view

2. Enable UDP helper.

   udp-helper enable

   By default, UDP helper is disabled.

3. Specify a UDP port number for UDP helper.

   udp-helper port { port-number | dns | netbios-ds | netbios-ns | tacacs | tftp | time }

   By default, no UDP port numbers are specified for UDP helper.

   Do not set UDP ports 67 and 68 for UDP helper, because UDP helper cannot forward DHCP broadcast packets.

   You can specify a maximum of 256 UDP ports for UDP helper.

4. Enter interface view.

   interface interface-type interface-number

5. Specify a destination multicast address for UDP helper to convert broadcast to multicast.

   udp-helper broadcast-map multicast-address [ acl acl-number ]

   By default, no destination multicast addresses are specified for UDP helper.

   Use this command on the interface that receives broadcast packets.

   You can specify a maximum of 20 unicast and multicast addresses for UDP helper to convert broadcast packets on an interface.