There are some cases in which a DeltaV PC that is configured to obtain its IP address automatically fails to communicate with the firewall at 192.168.1.1. For example, suppose that several DeltaV PCs are connected to a common network switch that is connected to the plant LAN and each PC is configured to obtain its IP address automatically. Then, a decision is made to connect the Emerson Smart Firewall between the network switch and the plant LAN. To accomplish this, the network switch is connected to the internal side of the firewall and the plant LAN to the external side of the firewall. Because the PCs are configured to obtain IP address automatically, it is assumed that in this case, the PCs are getting their IP addresses from the firewall. However, because the PCs maintained a connection to the switch while the firewall was installed, the PCs attempt to use their plant LAN addresses rather than request an IP address from the firewall and are unable to communicate with the firewall at 192.168.1.1. The PCs can be forced to request a new address by any of these methods: