The OkiLAN 6200e powers up but does not know its IP address. However, it does know its network hardware address.
It sends out a RARP request message with its network hardware address. For this example, the OkiLAN 6200e address is 00:02:16:17:50:A4.
The rarpd daemon running on a RARP server (in this example the RARP server is a UNIX workstation) sees the RARP request along with the network hardware address in the “/etc/ethers” file. The rarpd daemon finds the host name, OKIPRINTER, listed as the name associated with the network hardware address.
The rarpd then consults the “/etc/hosts” file and looks up the name OKIPRINTER. It finds an IP address (in this case 192.168.42.55) associated with the name OKIPRINTER.
The rarpd daemon transmits a response to the OkiLAN 6200e with the IP address 192.168.42.55. The OkiLAN 6200e will then use this IP address for all subsequent transmissions.
For all these steps to work properly, at least one RARP daemon (rarpd) must be running on the RARP server. On most UNIX systems, this can be tested by using the ps command with the show all processes option. Unfortunately, the ps options differ from one UNIX workstation to another. Perform a man ps at the UNIX prompt to consult a manual page on the ps command for a particular workstation. If rarpd is not running on a workstation, type man rarpd at the UNIX prompt to consult a manual page on the RARP daemon and how to start it.
Often TCP/IP networks are divided into subnets. RARP does not work across subnets. When installing an OkiLAN 6200e, make sure the following two criteria are met for RARP to work properly.
Both the RARP server and the OkiLAN 6200e are physically attached to the same subnet.
The IP address assigned to the OkiLAN 6200e and the IP address of the RARP server belong to the same subnet.