Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual page 3223

Example: Setting Up DHCP Option 82 with an EX Series Switch as Relay Agent Between
Clients and a DHCP Server
Requirements
Copyright © 2010, Juniper Networks, Inc.
Example: Configuring Port Security, with DHCP Snooping, DAI, MAC Limiting, and MAC
Move Limiting, on an EX Series Switch on page 3073
Example: Setting Up VoIP with 802.1X and LLDP-MED on an EX Series Switch on
page 2800
Configuring IP Source Guard (CLI Procedure) on page 3147
You can use DHCP option 82, also known as the DHCP relay agent information option,
to help protect the EX Series switch against attacks such as spoofing (forging) of IP
addresses and MAC addresses, and DHCP IP address starvation. Option 82 provides
information about the network location of a DHCP client, and the DHCP server uses this
information to implement IP addresses or other parameters for the client.
This example describes how to configure DHCP option 82 on a switch that is on the same
VLAN with the DHCP clients but on a different VLAN from the DHCP server; the switch
acts as a relay agent:
Requirements on page 3119
Overview and Topology on page 3120
Configuration on page 3120
This example uses the following hardware and software components:
One EX4200-24P switch
Junos OS Release 9.3 or later for EX Series switches
A DHCP server to provide IP addresses to network devices on the switch
Before you configure DHCP option 82 on the switch, be sure you have:
Connected and configured the DHCP server.
NOTE: Your DHCP server must be configured to accept DHCP option 82.
If it is not configured for DHCP option 82, it does not use the DHCP option 82
information in the requests sent to it when it formulates its reply messages.
Configured the employee
the clients connect to the switch with that VLAN. See "Configuring VLANs for EX Series
Switches (CLI Procedure)" on page 1600.
Configured the
corporate
Chapter 100: Examples: Port Security Configuration
VLAN on the switch and associated the interfaces on which
VLAN for the DHCP server.
3119