Alcatel-Lucent 6850-48 ネットワークガイド

Configuring DHCP Relay

DHCP Relay Overview

OmniSwitch AOS Release 6 Network Configuration Guide

page 31-7

The DHCP Relay may be configured on a router that is external to the switch. In this application example 
the switched network has a single VLAN configured with multiple segments. All of the network hosts are 
DHCP-ready, meaning they obtain their network address from the DHCP server. The DHCP server resides 
behind an external network router, which supports the DHCP Relay functionality.

One requirement for routing DHCP frames is that the router must support DHCP Relay functionality to be 
able to forward DHCP frames. In this example, DHCP Relay is supported within an external router, which 
forwards request frames from the incoming router port to the outgoing router port attached to the 
OmniSwitch.

The external router inserts the subnet address of the first hop segment into the DHCP request frames from 
the DHCP clients. This subnet address allows the DHCP server to locate the segment on which the 
requesting client resides. In this example, all clients attached to the OmniSwitch are DHCP-ready and will 
have the same subnet address (130.0.0.0) inserted into each of the requests by the router’s DHCP Relay 
function. The DHCP server will assign a different IP address to each of the clients. The switch does not 
need an IP address assigned and all DHCP clients will be members of either a default VLAN or an IP 
protocol VLAN.

130.0.0.11

130.0.0.12

130.0.0.14

130.0.0.13

130.0.0.15

125.0.0.1

125.0.0.2