Administrator Guide

ip helper-address
Specify the address of a DHCP server so that DHCP broadcast messages are forwarded when the DHCP server is not on the
same subnet as the client.
C9000 Series
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
Command
History
This guide is platform-specific. For command information about other platforms, refer to the relevant Dell
Networking OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version Description
9.9(0.0) Introduced on the C9010.
9.2(1.0) Introduced on the Z9500.
9.0.0.0 Added support for IPv6.
8.3.19.0 Introduced on the S4820T.
8.3.11.1 Introduced on the Z9000.
8.3.7.0 Introduced on the S4810.
8.1.1.0 Introduced on the E-Series ExaScale.
7.9.1.0 Introduced VRF on the E-Series.
7.6.1.0 Introduced on the S-Series.
7.5.1.0 Introduced on the C-Series.
6.2.1.1 Introduced on the E-Series.
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 system 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.
ipv6 helper-address
Configures the IPv6 DHCP helper addresses.
C9000 Series
Syntax
[no] ipv6 helper-address [vrf vrf-name] ipv6-address
Dynamic Host Configuration Protocol (DHCP) 629