Earlier versions of DHCP can be used only when the DHCP client and server reside on the same network segment. To dynamically assign IP addresses to hosts on network segments, the network administrator must configure a DHCP server on each network segment, which increases costs. The DHCP relay function solves this problem.
DHCPv4 and DHCPv6 relay applications are the same. The DHCP relay application described in this section covers both DHCPv4 and DHCPv6 relay. However, DHCPv4 and DHCPv6 relay cannot be used in the current version at the same time.