Nortel Networks NN47200-503 manual Global Dhcp relay commands Command Description

42An Introduction to IP Routing Protocols

Any of the Nortel Ethernet Routing Switch 5500 Series switch management systems can be used to set DHCP.

DHCP relay

DHCP (Dynamic Host Configuration Protocol) is a mechanism to assign network IP addresses to clients who request an address. It is built on top of the existing BOOTP protocol and can be specified for DHCP, BOOTP, or both.

The DHCP relay feature relays client requests to DHCP servers on different L3 VLANs. It also relays server replies back to the clients.

DHCP relay can be configured through Command Line Interface or Java Device Manager. DHCP can only be configured on the base unit from CLI, like all L3 commands. There are three parts in the DHCP relay configurations. They are:

•global DHCP enable/disable

•interface configurations

•forward path configurations

To relay DHCP messages, two VLANs must be created and IP addresses assigned to them. The client and server must reside on different L3 VLANS to use DHCP relay. IP routing and global DHCP relay must be enabled on both the client as well as server.

Note: The DHCP Relay feature shares resources with QoS. If the DHCP Relay feature is enabled, a QoS policy with a precedence of 11 cannot be installed.

For further information on QoS policies refer to Nortel Ethernet Routing Switch 5500 Series Configuration - Quality of Service (Part Number NN47200-504).

Global DHCP relay configuration This configuration enables or disables DHCP relay for the entire unit or stack. Once DHCP relay is disabled, the switch/stack will not relay DHCP/BOOTP " Global DHCP relay commands" (page 42)across L3 VLANs. However, the settings will still be configurable.

describes the global DHCP relay commands.

Global DHCP relay commands

Command	Description
show ip dhcp-relay	shows global DHCP relay state
no ip dhcp-relay	disables DHCP relay globally
ip dhcp-relay	enables DHCP relay globally

Nortel Ethernet Routing Switch 5500 Series

Configuration-IP Routing Protocols

NN47200-503 03.01 Standard

5.127 August 2007

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