External Dhcp Relay Application - Alcatel-Lucent OmniSwitch 9900 Series Network Configuration Manual

Configuring DHCP Relay

External DHCP Relay Application

The DHCP Relay can 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 that supports the DHCP Relay functionality.
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 that forwards request frames from the incoming router
port to the outgoing router port attached to the OmniSwitch.
125.0.0.1
DHCP Clients
IN
125.0.0.2
DHCP Server
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
have the same subnet address (130.0.0.0) inserted into each of the requests by the DHCP Relay function of
the router. The DHCP server assigns a different IP address to each of the clients. The switch does not need
an IP address assigned to it. All DHCP clients are members of either a default VLAN or an IP protocol
VLAN.
OmniSwitch AOS Release 8 Network Configuration Guide
External Router
with
DHCP Relay
OUT
130.0.0.11
DHCP Clients are Members of the Same VLAN
VLAN 1
130.0.0.12
DHCP Clients
130.0.0.13
DHCP Clients
December 2017
DHCP Relay Overview
OmniSwitch
130.0.0.14
130.0.0.15
DHCP Clients
page 21-6