ip helper-address

Configures a helper address on the interface connected to the client to enable forwarding of client broadcast request for a UDP application when the client and server are on different networks.
Syntax
ip helper-address address-number [ ip-address [ unicast ] ]
no ip helper-address address-number [ ip-address [ unicast ] ]
Command Default

IP helper address is not configured.

Parameters
address-number
Specifies the IP helper address number. Valid values are 1 to 16.
ip-address
Specifies the server IP address or the subnet directed broadcast address of the IPsubnet the server is in.
unicast
Specifies that the client request must be forwarded to the server that is on thesame network.
Modes

Interface configuration mode

Usage Guidelines

To forward a client broadcast request for a UDP application when the client and server are on different networks, you must configure a helper address on the interface connected to the client. Specify the server IP address or the subnet directed broadcast address of the IP subnet the server is in as the helper address.

You can configure up to 16 helper addresses on each interface. You can configure a helper address on an Ethernet port or a virtual interface.

By default, IP helper does not forward client broadcast request to a server within the network. To forward a client broadcast request when the client and server are on the same network, configure an IP helper with unicast option on the interface connected to the client.

The no form of the command removes the configured helper address.

Examples

The following example configures an IP helper address on Ethernet interface 1/1/1.

device(config)# interface ethernet 1/1/1
device(config-if-e1000-1/1/1)# ip helper-address 1 10.20.3.4 

The following example configures an IP helper address on Ethernet interface 1/2/2 to enable forwarding of broadcast request to a server within the network.

device(config)# interface ethernet 1/2/2
device(config-if-e1000-1/1/1)# ip helper-address 2 10.10.3.4 unicast