Concept Guide
INTERFACE mode
ipv6 helper-address [vrf vrf-name] ipv6-address
Conguring DHCP relay source interface
The following section explains how to congure global and interface level DHCP relay source IPv4 or IPv6 conguration to forward all the
DHCP packets from the DHCP client to DHCP server through the congured source interface. This feature is applicable only for L3
interface with relay conguration and L3 DHCP snooping enabled VLANs.
Global DHCP relay source IPv4 or IPv6 conguration
You can congure global DHCP relay source IPv4 or IPv6 conguration 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
congured interface for relaying packets to the DHCP server. For example, if you congure DHCP relay source interface as a loopback
interface, the DHCP relay uses the congured loopback interface to forward the packets to the DHCP server using the congured 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 conguration of global DHCP relay source IPv4 or IPv6 interface
Following is the sample conguration to congure 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 congure 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 congure the above commands in the CONFIGURATION MODE, it will congure the loopback interface as the DHCP relay
source interface for forwarding the DHCP packets from DHCP client to server. When this command is congured in the CONFIGURATION
mode level, it is applied globally. So, all the DHCP packets will be relayed or forwarded through the congured L3 interface (loopback 1)
using the IPv4 (1.1.1.1/32) and IPv6 addresses (1::1/128) of the loopback conguration.
Interface level DHCP relay source IPv4 or IPv6 conguration
You can congure interface specic DHCP relay source IPv4 or IPv6 conguration.
If the DHCP relay source interface is congured 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 congured in the interface level (if congured), the DHCP
relay chooses the congured global DHCP relay source interface for forwarding the packets.
NOTE
:
The DHCP relay source IPv4 or IPv6 conguration at interface level takes precedence over the DHCP relay source IPv4 or IPv6
conguration at the global level.
Dynamic Host Conguration Protocol (DHCP) 325