OptiConnect can give you the ability to define TCP/IP connections over an OptiConnect bus. This topic describes this feature and how it might be used.
TCP/IP over OptiConnect provides another method for the routing building blocks such as proxy ARP, unnumbered point-to-point networks, and virtual IP interfaces. You can configure this with an OptiConnect-emulated LAN configuration and an OptiConnect point-to-point configuration.
With an OptiConnect-emulated LAN configuration, the OptiConnect bus appears as a LAN to TCP/IP. This is simple to configure, but the LAN OptiConnect connectivity is not automatic because it requires Routing Information Protocol (RIP) or static routes.
The OptiConnect point-to-point configuration uses point-to-point unnumbered interfaces that are configured for each pair of OptiConnect hosts. No new networks are created and so the LAN OptiConnect connectivity is automatic. One advantage to this configuration is that no additional route definitions are required. Connectivity between a host on one network to hosts on another network is automatic. Another advantage is that if both networks are active, data sent between the systems flows over the OptiConnect bus because these routes have the most specific subnet mask. If the OptiConnect bus goes down, traffic is automatically switched to the token-ring LAN.
OptiConnect point-to-point configuration using virtual IP is a variation on the unnumbered point-to-point configuration. Remember that whenever you use unnumbered, point-to-point interfaces, each interface must have an associated local interface specified. This is the IP address by which the system on the remote end of the point-to-point link will know the local system. This associated local interface might be the system's primary LAN interface, as shown in the following figure. Or you can use a virtual IP interface as the associated local interface. In this configuration, you use the OptiConnect bus as a collection of point-to-point connections. You define an unnumbered connection for each pair of hosts. Like the previous configuration, no additional route definitions are required, and connectivity between a host on one network to hosts on the other network are automatic. An advantage of this configuration is that if either network is active, a path will exist to reach any system running on the i5/OS® operating system.