Scenario: PPP and DHCP on a single IBM i

Remote clients, such as dial-in clients, often require access to a company's network. Dial-in clients can gain access to a IBM i model with Point-to-Point Protocol (PPP) . To access the network, the dial-in client needs IP information just like any directly attached network client. A IBM i DHCP server can distribute IP address information to a PPP dial-in client just like any other directly attached client. The following figure shows a remote client that must dial into the company's network to do some work.

For the remote employee to successfully become part of the company's network, the IBM i model must use a combination of Remote Access Services and DHCP. The Remote Access Services function creates the dial-in capability for the IBM i model. If set up properly, after the client establishes the dial-in connection, the PPP server tells the DHCP server to distribute TCP/IP information to the remote client.

In this scenario, a single DHCP subnet policy covers both the on-site network clients and the dial-in clients.

If you want your PPP profile to defer to the DHCP for IP distribution, you must do so in the PPP profile. In the TCP/IP settings of the receiver connection profile, set the remote IP address assignment method from Fixed to DHCP. To allow the dial-in clients to communicate with other network clients, like the LAN printer, you must also allow IP forwarding in the TCP/IP settings of the profile and the TCP/IP configuration (stack) properties. If you only set IP forwarding on in the PPP profile, the IBM i model will not pass the IP packets. You must set IP forwarding on in both the profile and the stack.

Also, the local interface IP address in the PPP profile must be an IP address that falls within the subnet definition in the DHCP server. In this scenario, the PPP profile local interface IP address must be 10.1.1.1. This address must also be excluded from the DHCP server's address pool so that it is not assigned to a DHCP client.