Dell PowerEdge FN I/O Module Command Line Reference Guide 9.10(0.0)

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ip helper-address

Specify the address of a DHCP server so that DHCP broadcast messages can be forwarded when the DHCP server is not on the same subnet as the client.

Syntax

ip helper-address ip-address

To remove a DHCP server address, use the no ip helper-address command.

Parameters

ip-address

Enter an IP address in dotted decimal format (A.B.C.D).

Defaults

Not configured.

Command Modes

INTERFACE

Supported Modes

Full–Switch

Command History

Version	Description
9.9(0.0)	Introduced on the FN IOM.
8.3.16.1	Introduced on the MXL 10/40GbE Switch IO Module.

Usage Information

You can add multiple DHCP servers by entering the ip helper-address command multiple times. If multiple servers are defined, an incoming request is sent simultaneously to all configured servers and the reply is forwarded to the DHCP client.

The Dell Networking OS uses standard DHCP ports, that is UDP ports 67 (server) and 68 (client) for DHCP relay services. It listens on port 67 and if it receives a broadcast, the software converts it to unicast, and forwards to it to the DHCP-server with source port=68 and destination port=67.

The server replies with source port=67, destination port=67 and the system forwards to the client with source port=67, destination port=68.