Implementation
Cisco's first implementation of this protocol was introduced in version 10 of their router software. It is implemented through the use of the router configuration commands ip helper-address and ip forward-protocol.
ip helper-address
To enable the forwarding of User Datagram Protocol (UDP) broadcasts, including BOOTP, received on an interface, use the ip helper-address command in interface configuration mode. To disable the forwarding of broadcast packets to specific addresses, use the no form of this command.
Syntax Description: ip helper-address address no ip helper-address ' addressvrf name
(Optional) Enables VPN routing and forwarding (VRF) instance and VRF name.
global
(Optional) Configures a global routing table.
address
Destination broadcast or host address to be used when forwarding UDP broadcasts. There can be more than one helper address per interface.
redundancy vrg-name
(Optional) Defines the VRG group name.
Read more about this topic: UDP Helper Address