Concept Guide

INTERFACE mode
ipv6 helper-address [vrf vrf-name] ipv6-address
Conguring DHCP relay source interface
The following section explains how to congure global and interface level DHCP relay source IPv4 or IPv6 conguration to forward all the
DHCP packets from the DHCP client to DHCP server through the congured source interface. This feature is applicable only for L3
interface with relay conguration and L3 DHCP snooping enabled VLANs.
Global DHCP relay source IPv4 or IPv6 conguration
You can congure global DHCP relay source IPv4 or IPv6 conguration using the command {ip | ipv6} dhcp-relay source-
interface interface command in the CONFIGURATION mode. DHCP relay uses the IPv4 or IPv6 global source address of the
congured interface for relaying packets to the DHCP server. For example, if you congure DHCP relay source interface as a loopback
interface, the DHCP relay uses the congured loopback interface to forward the packets to the DHCP server using the congured IPv4 or
IPv6 address. The source interface can be a VLAN, LAG, physical and loopback interfaces.
• Specify the type of an interface and interface-number that should be used as a DHCP relay source interface.
CONFIGURATION mode
{ip | ipv6} dhcp relay source-interface interface
Example conguration of global DHCP relay source IPv4 or IPv6 interface
Following is the sample conguration to congure loopback interface with IPv4 and IPv6 address in CONFIGURATION MODE.
Dell(conf)# interface loopback 1
Dell(conf-if-lo-1)# ip vrf forwarding vrf1
Dell(conf-if-lo-1)# ip address 1.1.1.1/32
Dell(conf-if-lo-1)# ipv6 address 1::1/128
Dell(conf-if-lo-1)# no shutdown
To congure the loopback interface as IPv4 or IPv6 DHCP relay source interface, enter the following commands in the CONFIGURATION
MODE.
Dell(conf)# ip dhcp relay source-interface loopback 1
Dell(conf)# ipv6 dhcp relay source-interface loopback 1
When you congure the above commands in the CONFIGURATION MODE, it will congure the loopback interface as the DHCP relay
source interface for forwarding the DHCP packets from DHCP client to server. When this command is congured in the CONFIGURATION
mode level, it is applied globally. So, all the DHCP packets will be relayed or forwarded through the congured L3 interface (loopback 1)
using the IPv4 (1.1.1.1/32) and IPv6 addresses (1::1/128) of the loopback conguration.
Interface level DHCP relay source IPv4 or IPv6 conguration
You can congure interface specic DHCP relay source IPv4 or IPv6 conguration.
If the DHCP relay source interface is congured on the interface level, the DHCP relay forwards the packets from these interfaces to the
DHCP server using the interface. In case, the DHCP relay source interface is not congured in the interface level (if congured), the DHCP
relay chooses the congured global DHCP relay source interface for forwarding the packets.
NOTE
:
The DHCP relay source IPv4 or IPv6 conguration at interface level takes precedence over the DHCP relay source IPv4 or IPv6
conguration at the global level.
332 Dynamic Host Conguration Protocol (DHCP)