Dell Command Line Reference Guide for the S4048–ON System 9.14.2.8

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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
Command History

This guide is platform-specific. For command information about other platforms, see the relevant Dell EMC Networking OS Command Line Reference Guide.

Version
Description
9.10(0.1)
Introduced on the S6010-ON and S4048T-ON.
9.10(0.0)
Introduced on the S3148.
9.10(0.0)
Introduced on the S6100–ON.
9.8(2.0)
Introduced on the S3100 series.
9.8(1.0)
Introduced on the Z9100–ON.
9.8(0.0P5)
Introduced on the S4048-ON.
9.8(0.0P2)
Introduced on the S3048-ON.
9.7(0.0)
Introduced on the S6000-ON.
9.2(1.0)
Introduced on the Z9500.
9.0.2.0
Introduced on the S6000.
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.
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.
pre-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.

Dell EMC 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 Dell EMC Networking OS forwards to the client with source port=67, destination port=68.


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