Administrator Guide

Interface level DHCP relay source IPv4 or IPv6
configuration
You can configure interface specific DHCP relay source IPv4 or IPv6 configuration.
If the DHCP relay source interface is configured 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 configured in the interface level (if configured), the
DHCP relay chooses the configured global DHCP relay source interface for forwarding the packets.
NOTE:
The DHCP relay source IPv4 or IPv6 configuration at interface level takes precedence over the DHCP relay source IPv4
or IPv6 configuration at the global level.
• Specify the type of an interface and interface-number that should be used as a DHCP relay source interface at the interface level.
INTERFACE mode
{ip | ipv6} dhcp relay source-interface interface
Following are the steps to configure interface specific source IPv4 or IPv6 configuration for DHCP relay. The below example shows when
the DHCP relay uses the interface specific configuration and global source interface configuration depending on the configuration.
1. Configuring L3 interface with IPv4 or IPv6 address.
Following are the steps to configure a L3 interface (loopback) with IPv4 and IPv6 address in INTERFACE MODE.
Dell(conf)# interface loopback 2
Dell(conf-if-lo-1)# ip vrf forwarding vrf1
Dell(conf-if-lo-1)# ip address 2.2.2.2/32
Dell(conf-if-lo-1)# ipv6 address 2::2/128
Dell(conf-if-lo-1)# no shutdown
Dell(conf)# interface loopback 3
Dell(conf-if-lo-1)# ip vrf forwarding vrf2
Dell(conf-if-lo-1)# ip address 3.3.3.3/32
Dell(conf-if-lo-1)# ipv6 address 3::3/128
Dell(conf-if-lo-1)# no shutdown
2. Creating L3 interfaces with the DHCP helper configuration.
Following are the steps to configure IPv4 or IPv6 interfaces with the DHCP helper configuration. The below example shows two VLAN
interfaces (Vlan 2 and 4), DHCP helper (100.0.0.1 and 100::1) for the respective VLANs and the DHCP relay source IPv4 and IPv6
configuration, and two different loopback interfaces (loopback 2 and 3). DHCP relay forwards packets using the loopback 2 interface
with IPv4 and IPv6 addresses ((2.2.2.2/32 and 2::2/128) from Vlan 2. The same way, the relay uses IPv4 and IPv6 addresses
(3.3.3.3/32 and 3::3/128) of loopback 3 interface from Vlan 3.
Dell(conf)# interface Vlan 2
Dell(conf-if-vl-2)# ip vrf forwarding vrf1
Dell(conf-if-vl-2)# ip address 2.0.0.1/24
Dell(conf-if-vl-2)# ipv6 address 2::1/64
Dell(conf-if-vl-2)# tagged fortyGigE 0/0
Dell(conf-if-vl-2)# ip helper-address vrf vrf1 100.0.0.1
Dell(conf-if-vl-2)# ipv6 helper-address vrf vrf1 100::1
Dell(conf-if-vl-2)# ip dhcp relay source-interface loopback 2
Dell(conf-if-vl-2)# ipv6 dhcp relay source-interface loopback 2
Dell(conf)# interface Vlan 4
Dell(conf-if-vl-4)# ip vrf forwarding vrf1
Dell(conf-if-vl-4)# ip address 4.0.0.1/24
Dell(conf-if-vl-4)# ipv6 address 4::1/64
Dell(conf-if-vl-4)# tagged fortyGigE 0/4
Dell(conf-if-vl-4)# ip helper-address vrf vrf1 100.0.0.1
Dell(conf-if-vl-4)# ipv6 helper-address vrf vrf1 100::1
Dell(conf-if-vl-4)# ip dhcp relay source-interface loopback 3
Dell(conf-if-vl-4)# ipv6 dhcp relay source-interface loopback 3
3. In the below configuration, the DHCP relay source interface is not configured in the VLAN interface. So, the DHCP relay uses the
configured global DHCP relay source interface to forward the packets from the DHCP client to server.
Dell(conf)# interface Vlan 5
Dell(conf-if-vl-4)# ip vrf forwarding vrf1
Dell(conf-if-vl-4)# ip address 4.0.0.1/24
Dell(conf-if-vl-4)# ipv6 address 4::1/64
Dynamic Host Configuration Protocol (DHCP)
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