Administrator Guide

Non-default VRF configuration for DHCPv6 helper
address
The ipv6 helper-address command is enhanced to provide support for configuring VRF for DHCPv6 relay helper address. To
forward DHCP packets between DHCP client and server if they are from different VRFs, you should configure route leak using route map
between the VRFs. For more information on configuring route leak across VRF, see
DHCP Relay when DHCP Server and Client are in
Different VRFs.
NOTE:
For DHCP relay source IPv4 or IPv6 configuration 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
Configuring DHCP relay source interface
The following section explains how to configure global and interface level DHCP relay source IPv4 or IPv6 configuration to forward all the
DHCP packets from the DHCP client to DHCP server through the configured source interface. This feature is applicable only for L3
interface with relay configuration and L3 DHCP snooping enabled VLANs.
Global DHCP relay source IPv4 or IPv6 configuration
You can configure global DHCP relay source IPv4 or IPv6 configuration 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
configured interface for relaying packets to the DHCP server. For example, if you configure DHCP relay source interface as a loopback
interface, the DHCP relay uses the configured loopback interface to forward the packets to the DHCP server using the configured 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
Following is the sample configuration to configure 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 configure 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 configure the above commands in the CONFIGURATION MODE, it will configure the loopback interface as the DHCP relay
source interface for forwarding the DHCP packets from DHCP client to server. When this command is configured in the
CONFIGURATION mode level, it is applied globally. So, all the DHCP packets will be relayed or forwarded through the configured L3
interface (loopback 1) using the IPv4 (1.1.1.1/32) and IPv6 addresses (1::1/128) of the loopback configuration.
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Dynamic Host Configuration Protocol (DHCP)