Alcatel-Lucent 6850-48 Network Guide

DHCP Relay Overview

Configuring DHCP Relay

page 31-8

OmniSwitch AOS Release 6 Network Configuration Guide

The internal DHCP Relay is configured using the UDP forwarding feature in the switch, available through 
the 

 command. For more information, see 

.

This application example shows a network with two VLANs, each with multiple segments. All network 
clients are DHCP-ready and the DHCP server resides on just one of the VLANs. This example is much 
like the first application example, except that the DHCP Relay function is configured inside the switch.

During initialization, each network client forwards a DHCP request frame to the DHCP server using the 
local broadcast address. For those locally attached stations, the frame will simply be switched.

In this case, the DHCP server and clients must be members of the same VLAN (they could also all be 
members of the default VLAN). One way to accomplish this is to use DHCP rules in combination with IP 
protocol rules to place all IP frames in the same VLAN. See 

 for more 

information.

Because the clients in the application example are not members of the same VLAN as the DHCP server, 
they must request an IP address via the DHCP Relay routing entity in the switch. When a DHCP request 
frame is received by the DHCP Relay entity, it will be forwarded from VLAN 3 to VLAN 2. All the 
DHCP-ready clients in VLAN 3 must be members of the same VLAN, and the switch must have the 
DHCP Relay function configured.

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