Figure 5-26. TCP/IP Direct Connect Configuration Screens
Notice also that the subnet these two addresses are in is different than the subnet of the server’s LAN adapter (207.168.12.68). Microsoft’s TCP/IP stack can be configured to automatically forward IP packets between network adapters as long as those adapters are in different subnets. However, Microsoft’s TCP/IP cannot forward packets between to adapters when the IP addresses are in the same subnet.
Please refer to Microsoft documentation for information on configuring TCP/IP to perform IP Packet Forwarding.
To complete the network configuration add a static route to the router between the Ethernet and Token-Ring LANs that re-directs all traffic destined for 207.168.12.129 (the mainframe) to 207.168.12.68 (the server). Since all workstations on both LANs define the router as their default gateway they will go to the router when they want to attach to the mainframe (because it is not in their subnet). For workstations on the Ethernet LAN, the static route will be used to forward the messages to the server. For workstations on the token-ring, the router will see that the server and workstation are in the same subnet and send an Internet Control Message Protocol (ICMP) Route message to the workstation to update its route information. Future packets for the mainframe will be sent directly from the workstation to the server (207.168.12.68).