an embodiment of the invention will now be described with reference to the flow chart of fig3 in this embodiment each physical port of the first switch is coupled to only one device and the first switch 22 is configured to only enable a single mac media access control address per physical port thus for example the three robot arms 20 a c and a controller could not be attached to a hub with the hub connected to one of the physical ports of the first switch 22 thus the first switch 22 can be configured to control the traffic between each device to prevent broadcast storms and other security related problems in this embodiment it is assumed the manufacturing floor is isolated properly from the corporate network and or the internet also as described above devices networked on the manufacturing floor tend to utilize a limited number of specialized protocols such as the common industrial protocol cip as is known in the art upper layer applications that use tcp transmission control protocol or udp user datagram protocol are identified by a tcp udp port number packets transmitted utilizing tcp or udp include a source and destination tcp udp port numbers for each physical port of the switch connected to a device in the workgroup only packets with tcp udp port numbers identifying the protocol used by the device connected are allowed ingress to the first switch 22 for example the tcp port number for cip for transmission by either tcp or udp is 0xaf12 and this tcp port number is included in each packet transmitted by a connected device the first switch is configured to.