Administrator Guide

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
Dell(conf-if-vl-4)# tagged TenGigE 1/4
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
Configure the System for User Port Stacking
(Option 230)
Set the stacking-option variable to provide stack-port detail on the DHCP server when you set the DHCP offer. A stack can be formed
when the units are connected.
Option 230 is the option for user port stacking. Use it to create up to eight stack groups. Define the configuration parameters on the
DHCP server for each chassis based on the chassis MAC address. Configure the following parameters:
• unit number
• priority
• stack group ID
The received stacking configuration is always applied on the master stack unit.
option #230 "unit-number:3#priority:2#stack-group:14"
Configure Secure DHCP
DHCP as defined by RFC 2131 provides no authentication or security mechanisms. Secure DHCP is a suite of features that protects
networks that use dynamic address allocation from spoofing and attacks.
• Option 82
• DHCP Snooping
• Dynamic ARP Inspection
• Source Address Validation
Option 82 (DHCPv4 relay options)
RFC 3046 (the relay agent information option, or Option 82) is used for class-based IP address assignment.
The code for the relay agent information option is 82, and includes two suboptions, circuit ID and remote ID.
Circuit ID
This is the interface on which the client-originated message is received.
Remote ID This identifies the host from which the message is received. The value of this suboption is the MAC address of
the relay agent that adds Option 82.
In DHCPv4 relay , the Option 82 is not added by default. When the
ip dhcp relay information-option is configured, the Option
82 with suboptions 1 (Agent Circuit ID) and 2 ( Agent Remote ID) are added to the relayed DHCP packet. The default values of the
suboptions are as follows:
• Default Agent Circuit ID is constructed in the format VLANID:LagID:SlotID:PortStr. When the port is fanned-out, the
PortStr is represented as mainPort:subPort (all in ASCII format).
• Default Agent Remote ID is the system MAC address (in binary format).
The following example shows the format of the Circuit ID - 723:0:1:1.
244
Dynamic Host Configuration Protocol (DHCP)