HP 7000 dl Router manual Copyright 2005 Hewlett-Packard Development Company, L.P 859

SROS Command Line Interface Reference Guide Loopback Interface Configuration Command Set

ip helper-address <address>

Use the ip helper-addresscommand to configure the Secure Router OS to forward User Datagram Protocol (UDP) broadcast packets received on the interface. Use the no form of this command to disable forwarding packets.

Note	The ip helper command must be used in conjunction with the ip forward-protocolcommand
	to configure the Secure Router OS to forward UDP broadcast packets.
Syntax Description
<address>	Specifies the destination IP address (in dotted decimal notation) for the forwarded
	UDP packets.

Default Values

By default, broadcast UDP packets are not forwarded.

Command Modes

(config-interface)#	Interface Configuration Mode required (applies to all physical interfaces as well as
	virtual interfaces)

Functional Notes

When used in conjunction with the ip forward-protocolcommand, the ip helper-addressfeature allows you to customize which broadcast packets are forwarded.

To implement the helper address feature, assign a helper-address(es) (specifying the device that needs to receive the broadcast traffic) to the interface closest to the host that transmits the broadcast packets. When broadcast packets (of the specified type forwarded using the ip forward-protocolcommand) are received on the interface, they will be forwarded to the device that needs the information.

Only packets meeting the following criteria are considered eligible by the ip helper-addressfeature:

1.The packet IP protocol is User Datagram Protocol (UDP).

2.Any UDP port specified using the ip forward-protocolcommand.

3.The media access control (MAC) address of the frame is an all-ones broadcast address (ffff.ffff.ffff).

4.The destination IP address is broadcast defined by all ones (255.255.255.255) or a subnet broadcast (for example, 192.33.4.251 for the 192.33.4.248/30 subnet).

5991-2114 © Copyright 2005 Hewlett-Packard Development Company, L.P. 859