You might need to use a DHCP relay agent in your network; sometimes a router is sufficient. You can use both a DHCP relay agent and a router to efficiently and securely transfer data throughout the network.
Initially, DHCP clients broadcast their DISCOVER packets because they do not know what network they are connected to. In some networks, the DHCP server might not be on the same LAN as the client. Therefore, it is necessary to forward the client's broadcast DHCP packets to the LAN where the DHCP server is. Some routers are configured to forward DHCP packages. If your router supports DHCP packet forwarding, that is all you need. However, many routers do not forward packets that have a destination IP address of the broadcast address (DHCP packets). In this case, if the router cannot forward DHCP packets, then the LAN must have a BOOTP/DHCP relay agent to forward the DHCP packets to the LAN with the DHCP server. Refer to Example: DHCP and PPP profile on different iSeries™ servers for a sample network using a relay agent and a router.
In either case, because the DHCP server is on a separate network, your clients will need to have the router option (option 3) defined that specifies the IP address of the router that connects their network to the network with the DHCP server.
In these scenarios, if you do not use a BOOTP/DHCP relay agent, you will need to add a DHCP server to the other LAN to serve those clients. To help you decide how many DHCP servers to have in your network, refer to Network topology considerations.