Figure 45: Cpe330 Overlapping Local Ip Subnet Example - GE PACSystems RX7i Reference Manual

The following examples would be problematic:
Problem example #1:
The issue demonstrated in Figure 45 is that requests entering one CPE330 interface can be routed out
the other interface since both CPE330 Ethernet ports have been configured to be on the same network
(255.255.0.0) but are physically connected to separate networks. Avoid this by assigning non-overlapping
Subnets.
Problem example #2:
A user wishes to communicate through a routed network to an RX3i CPU with multiple network
interfaces (CPE330, in this example). This remote IP device is configured with the following IP parameters:
IP 192.168.0.5
Subnet Mask 255.255.255.0
Gateway 192.168.0.250
LAN1 and LAN2 on the CPE330 are initially configured with following problematic IP parameters:
LAN1
IP 10.10.0.1
Subnet Mask 255.255.255.0 255.255.255.0
Gateway 10.10.0.249
The user intends to communicate between the remote device and CPE330 LAN1 (Figure 46). IP Address
routing allows the CPE330 to receive the remote IP requests through the respective gateways
(192.168.0.250 for the remote node and 10.10.0.249 for CPE330 LAN1). However, since CPE330 LAN2
shares the same IP subnet as the remote network (192.168.0.x), responses may be routed to the local
192.168.0.x network rather than to the remote network (Figure 47).
The duplicate IP subnet in the example must be eliminated. One way to do this is simply change the IP
Address assigned to CPE330 LAN2 from 192.168.0.1 to 192.168.1.1 thereby creating a non-overlapping
192.168.1.x network. In short, consider the totality of the network when assigning IP subnets and IP
Addresses.
GFK-2222AD

Figure 45: CPE330 Overlapping Local IP Subnet Example

LAN2
192.168.0.1
0.0.0.0
April 2018
Chapter 5. Communications
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