Dhcp Relay Overview - Juniper NETWORK AND SECURITY MANAGER 2010.4 - CONFIGURING SCREENOS DEVICES GUIDE REV 01 Manual

Configuring ScreenOS Devices Guide
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DHCP Relay Overview

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410
Route Types Overview on page 295
3GPP R6 Information Elements Support Overview on page 407
DHCP Relay Overview on page 410
Configuring Access Point Name Restriction (NSM Procedure) on page 409
Dynamic Host Configuration Protocol (DHCP) was designed to reduce the demands on
network administrators by automatically assigning the TCP/IP settings for the hosts on
a network. Some security devices can also act as DHCP relay agents, receiving DHCP
information from a DHCP server and relaying that information to hosts on any physical
or VLAN interface in any zone.
When acting as a DHCP relay agent, the security device forwards DHCP requests and
assignments between DHCP clients directly attached to one interface and one or more
DHCP servers accessible through another interface. The clients and servers may be in
the same security zone or in separate security zones.
You can configure a DHCP relay agent on one or more physical or VLAN interfaces on a
security device, but you cannot configure a DHCP relay agent and DHCP server or client
functions on the same interface.
When the security device functions as a DHCP relay agent, its interfaces must be in either
Route mode or function as a Layer 3 device. For interfaces in Layer 3 mode (that is have
IP addresses assigned to the interfaces), you must configure a security policy (from zone
to zone or intrazone) to permit the predefined service DHCP Relay before forwarding
occurs.
You can configure up to three DHCP servers for each DHCP relay agent. The relay agent
unicasts an address request from a DHCP client to all configured DHCP servers. The relay
agent forwards to the client all DHCP packets received from all servers. For more
information on DHCP configuration, see the Concepts & Examples ScreenOS Reference
Guide.
NOTE: When a security device acts as a DHCP relay agent, the device does
not generate DHCP allocation status reports because the remote DHCP server
controls all the IP address allocations.
Route Types Overview on page 295
3GPP R6 Information Elements Support Overview on page 407
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