Example: Multiple TCP/IP subnets
This example explains how to set up a System i™ model as a Dynamic Host Configuration Protocol (DHCP) server with two LANs connected by a DHCP-enabled router.
This example is similar to the Simple DHCP subnet example except that there is now an additional TCP/IP subnet. Suppose that the office and data entry clients are on different floors of an office building and are separated with a router. If the network administrator wants all of the clients to receive their IP information through DHCP, this situation presents some unique differences from a simple DHCP subnet. The following figure shows an example network layout for a System i DHCP server connected to two LANs using a router between the networks. The figure intentionally has a limited number of clients so as not to become cluttered. An actual enterprise generally has considerably more clients on each subnet.
Figure 1. Multiple LANs connected through a routerThe router that connects the two networks must be enabled to pass DHCP DISCOVER packets. If it is not, the data entry clients will not be able to receive their IP information and access the network. Also, the DHCP policy needs two subnet definitions--one for the data entry subnet and the other for the office subnet. At a minimum, the differences between the subnets are their IP subnets and router addresses. The data entry subnet needs to receive a router address of 10.1.2.2 to communicate with the office subnet.
Planning the DHCP setup for multiple LANs
Table 1. Global configuration options (applies to all clients served by the DHCP server) Object Value Configuration options option 1: Subnet mask 255.255.255.0 option 6: Domain name server 10.1.1.1 option 15: Domain name mycompany.com Subnet addresses not assigned by the system 10.1.1.1 (Domain name server) Is the system performing DNS updates? No Is the system supporting BOOTP clients? No
Table 2. Subnet for Office clients Object Value Subnet name Office Addresses to manage 10.1.1.3 - 10.1.1.150 Lease time 24 hours (default) Configuration options option 3: Router 10.1.1.2 inherited options Options from Global configuration Subnet addresses not assigned by server 10.1.1.2 (Router)
Table 3. Subnet for Data Entry clients Object Value Subnet name DataEntry Addresses to manage 10.1.2.3 - 10.1.2.150 Lease time 24 hours (default) Configuration options option 3: Router 10.1.2.2 Inherited options Options from Global configuration Subnet addresses not assigned by server 10.1.2.2 (Router)
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Examples: DHCPRelated reference
Example: Simple DHCP subnet