Dell SmartFabric OS10 User Guide Release 10.5.3

System operation and behavior

In network configurations where a firewall gateway exists between the DHCP relay agent and the DHCP server, only the trusted IP addresses passes through this firewall. In such a scenario, the DHCP unicast packets do not pass through the firewall and are discarded.

The DHCP relay agent source-interface IP configuration places the loopback address in the IP headers and DHCP messages. This action enables the DHCP unicast packets to pass through the firewall to the DHCP server.

Following is the format of the source-interface value with interface loopback and Ethernet:

 loopback  as interface :
        <loopback>  <loopback_interface_no>
        e.g: loopback_interface_no ranges from  <0-16383>  
        e.g.: ipv6 dhcp-relay source-interface loopback 1
       
        Ethernet as interface :
        <ethernet >  <node/slot/port[:subport]>
        e.g.: ipv6 dhcp-relay source-interface ethernet 1/1/1

OS10-Relay(conf-if-eth1/1/1)# show configuration
!
interface ethernet1/1/1
no shutdown
no switchport
ipv6 address 66::67/64
flowcontrol receive off
ipv6 helper-address 88::89
ipv6 dhcp-relay source-interface loopback1
OS10-Relay(conf-if-eth1/1/1)#

OS10-Relay(conf-if-eth1/1/2)# show configuration
!
interface ethernet1/1/2
no shutdown
no switchport
ipv6 address 88::88/64
flowcontrol receive off
OS10-Relay(conf-if-eth1/1/2)#

OS10-Server(conf-if-eth1/1/2)# show configuration
!
interface ethernet1/1/2
no shutdown
no switchport
ipv6 address 88::89/64
flowcontrol receive off
OS10-Server(conf-if-eth1/1/2)#

OS10-Server(config-dhcp-pool1)# show configuration
!
pool pool1
network 66::60/64
OS10-Server(config-dhcp-pool1)#

OS10-Client(conf-if-eth1/1/1)# show configuration
!
interface ethernet1/1/1
no shutdown
no switchport
ipv6 address dhcp
flowcontrol receive off