Concept Guide

Non-default VRF conguration for DHCPv6 helper
address
The ipv6 helper-address command is enhanced to provide support for conguring VRF for DHCPv6 relay helper address. To
forward DHCP packets between DHCP client and server if they are from dierent VRFs, you should congure route leak using route map
between the VRFs. For more information on conguring route leak across VRF, see
DHCP Relay when DHCP Server and Client are in
Dierent VRFs.
NOTE:
For DHCP relay source IPv4 or IPv6 conguration to work in non-default VRF, you must enable VPN in DHCP information option.
• Specify the helper-address and VRF name (optional) to forward the DHCPv6 relay packets from client and server.
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
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Dynamic Host Conguration Protocol (DHCP)