Multi-Tech Systems 40-01459-D0-001 manual Subnet 207.168.12.1 207.168.12.65

Subnet 0	207.168.12.1 – 207.168.12.62
Subnet 1	207.168.12.65 – 207.168.12.126
Subnet 2	207.168.12.129 – 207.168.12.190
Subnet 3	207.168.12.193 – 207.168.12.254

As shown, the Ethernet segment makes up subnet 0 and the Token-Ring makes up subnet 1. Subnets 2 and 3 are currently not used. The router’s Ethernet port is assigned an IP address in Subnet 0 and the Token-Ring port is assigned an address in subnet 1.

Workstations on the Ethernet LAN are configured with their Default Gateway set to 207.168.12.1. Workstations and the server on the Token-Ring have their Default Gateway set to 207.168.12.65.

Adding a TCP/IP link to a mainframe from the server in this environment is easy and straightforward. Figure 5-25 shows how the network might look after a PCI ESCON Adapter and TCP/IP Direct Connect have been added to the server.

	207.168.12.67
	207.168.12.1
207.168.12.68
		207.168.12.2

207.168.12.130		207.168.12.3
	207.168.12.65
207.168.12.129	207.168.12.66	207.168.12.4
Figure 5-25. Installing TCP/IP Direct Connect into Network

Notice that a new IP address has been assigned to TCP/IP Direct Connect (207.168.12.130) and to the Mainframe (207.168.12.129). These addresses are both part of subnet 2 which was unused before the ESCON adapter was installed. The addresses must both be in the same subnet in order for Microsoft TCP/IP to send TCP/IP traffic across to the Mainframe. If the mainframe were in a different subnet than TCP/IP Direct Connect, TCP/IP would incorrectly attempt to identify an IP address for a gateway in order to get to the mainframe.

Figure 5-26 shows the TCP/IP Direct Connect Configuration for this example.

42 PCI ESCON Adapter Installation Guide