TCP/IP routing method for i5/OS

Standard TCP/IP routing is used to route traffic to the virtual Ethernet network in the same way you define routing to any other LAN. This requires that you update routing information throughout your network.

You can also route traffic to your partitions through i5/OS^® with various routing techniques. This solution is not difficult to configure on the system but, depending on the topology of your network, it might not be practical to implement. Consider the following figure.

The existing TCP/IP interface (10.1.1.2) connects to the LAN. The LAN is connected to remote networks with a router. The virtual TCP/IP interface on partition B is addressed as 10.1.10.2 and the virtual TCP/IP interface on partition A as 10.1.10.1. In i5/OS, if you turn on IP datagram forwarding, i5/OS will route the IP packets to and from partition B. When you define your TCP/IP connection for partition B, the router address must be 10.1.10.1.

The difficulty of this type of routing is getting the IP packets to the system. In this scenario, you can define a route on the router so that it passes packets destined to the 10.1.10.0 network to the 10.1.1.2 interface. That works for remote network clients. It also works for the local LAN clients (clients connected to the same LAN as the System i™ platform) if they recognize that same router as their next hop. If they do not, then each client must have a route that directs 10.1.10.0 traffic to the i5/OS 10.1.1.2 interface; therein starts the impracticability of this method. If you have many LAN clients, then define many routes.

To configure virtual Ethernet to use the TCP/IP routing method, use the following instructions:

Step 1: Enabling logical partitions to participate in a virtual Ethernet
The first step for associating the virtual interface with an external interface is to enable virtual Ethernet.
Step 2: Creating Ethernet line descriptions
You need to perform this step in one of two ways depending on the system model you are using. Select the appropriate procedure for your particular model.
Step 3: Turning on IP datagram forwarding
Turn on IP datagram forwarding so that the packets can be forwarded among different subnets.
Step 4: Creating the interfaces
To allow traffic between your virtual Ethernet network and the external network, you need to create several TCP/IP interfaces for your system.

Parent topic:

TCP/IP techniques connecting virtual Ethernet to external LANs