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| 2.8 |  | Helper Addresses |
| 2.8.2 |  | Configuring IP helper addresses |

To configure the helper address, identify the router interface that will be receiving the broadcasts for UDP services. In the interface configuration mode, use the ip helper-address command to define the address to which UDP broadcasts for services should be forwarded.

By default, the

ip helper-address command forwards the eight UDPs services shown in Figure .

What if Company XYZ needs to forward requests for a service not on this list? The Cisco IOS provides the global configuration command

ip forward-protocol to allow an administrator to forward any UDP port in addition to the default eight. In order to forward UDP on port 517, use the global configuration command, ip forward-protocol udp 517. This command is used not only to add a UDP port to the default eight, but also to subtract an unwanted service from the default group. When forwarding DHCP, TFTP, and DNS without forwarding Time, TACACS, and NetBIOS, the Cisco IOS requires that the router be configured according to the syntax in Figure .

| Lab Activity e-Lab Activity: Configuring IP Helper Addresses This lab is to configure an IP helper address.