Dell SmartFabric OS10 User Guide Release 10.5.3

Parameter assignment based on Interface-ID option

The DHCPv6 server uses link addresses in the DHCPv6 RELAY-FORWARD packet to select the subnet from which the IPv6 address is assigned to the clients. If interface-ID option is enabled, then the interface-ID option in the RELAY-FORWARD packet is used to select the subnet and other configuration parameters. The DHCPv6 server is configured with the policy to assign IPv6 address or configuration parameters based on the interface-ID.

In the following diagram, the Host1, Host2, and Host3 could get different set of DHCPv6 subnet and configuration parameters based on the interface-ID option.

The interface description is a combination of VLAN and port information. By default, the interface name is used for the interface description. The VLAN name and the port name are separated by a hyphen (-). You can optionally configure the customized string for each interface using textual description configuration.

The prefix is an optional parameter to be configured globally. You can configure hostname, VRF Name, hostname, and VRF name or customized string as prefix. Optionally, you can also configure DHCPv6 hostname. For example, Prefix:<VLAN name>-<Port name>.

Following are the different formats of the interface-ID value with different configurations of the prefix.

 Host name as prefix :
        <Host name> : <VLANname>-<Portname>
        e.g.: DELL OS10:vlan200-ethernet1/1/2

        VRF Name as prefix :
        <VRF Name of the interface> : <VLANname>-<Portname>
        e.g.: RED:vlan200-ethernet1/1/2

        Both Host name and VRF Name as prefix :
        <Host name>-<VRF Name of the interface> : <VLANID>-<Portname>
        e.g.: DELL OS10-RED:vlan200-ethernet1/1/2

CLI Configuration:

DHCP Relay Agent:

Global config:
ipv6 dhcp-relay interface-id
ipv6 dhcp-relay prefix interface-id hostname
ipv6 dhcp-relay hostname DELL

OS10#show running-configuration
interface Ethernet 1/1/1
no shutdown
switchport mode trunk
switch port trunk allowed vlan 10
ipv6 dhcp-relay interface-id description PORT
!
interface vlan 10 
no shutdown
ip address 1.1.1.1/24
ip helper-address 20.1.1.2
ipv6 dhcp-relay interface-id description VLAN
!
interface Ethernet 1/1/2
no shutdown
ip address 20.1.1.1
!

DHCP Server

OS10(config)# ip dhcp server
OS10(config-dhcp)# pool dell_1
OS10(config-dhcp-dell_1)# network 10.1.1.0/24
OS10(config-dhcp-dell_1)# range 10.1.1.2 10.1.1.10
OS10(config-dhcp-dell_1)# default-router 10.1.1.1
OS10(config-dhcp-dell_1)# end

OS10(config-dhcp)# pool dell_2
OS10(config-dhcp-dell_2)# network 20.1.1.0/24
OS10(config-dhcp-dell_2)# range 20.1.1.2 20.1.1.10
OS10(config-dhcp-dell_2)# default-router 20.1.1.1
OS10(config-dhcp-dell_2)# end
OS10#show running-config ip dhcp
!
ip dhcp server
!
ip dhcp pool dell_1
network 10.1.1.0/24
default-router 10.1.1.1
address range 10.1.1.2 10.1.1.10

ip dhcp pool dell_2
network 20.1.1.0/24
default-router 20.1.1.1
address range 20.1.1.2 20.1.1.10

In this scenario, the interface-id value: DELL:VLAN-PORT is added in the packet and sent out of DHCPv6 relay agent. You can configure the DHCP server to allocate an IP address from a range of IP addresses based on the interface-id value that is received from the DHCPv6 packet. The prefix value is configured to take hostname: DELL(DHCPv6 hostname) and interface description is configured in both the VLAN and physical interface (VLAN and PORT).