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Uwe Nolte

Manager Network Technology, Phoenix Contact Electronics

Uwe Nolte is manager for product marketing network technology at Phoenix Contact Electronics, Bad Pyrmont, Germany. He has more than 20 year experience with fieldbus applications, control technology and industrial Ethernet communication. His main focus is on high-available network concepts including feasible redundancy and security methods.

High-available Ethernet network concepts

Digital Oilfield, Wireless and Industrial Communications

Abstract: A key objective of every plant operator is high availability along with control and guidance functions, so the network structure of process plants plays an essential role. This paper shows typical and proven concepts to setup highly available, redundant field and control networks. High system availability is usually achieved by providing redundant data paths that ensure the communication needed for further operation if the network elements, such as data lines, fail. The redundancy management system for the activation of redundant network is therefore already integrated in the network infrastructure. Within this context, the established network topology and automation structure, as well as the framework conditions resulting from the application protocols in use, must be taken into account. Depending on the network structure communication redundancy can be implemented on switch level (layer 2) or on a routing/ firewall connection (layer 3). For layer 3 redundancy two router or firewall-devices work as a redundancy pair which acts as one virtual router for the connected sub-networks. On layer 3-level the switch-over- time is less critical whereas this can be significant on layer 2 especially in field networks. With automation protocols like Profinet and Ethernet/IP redundant concepts can be created by combining switches and two-port field devices in one ring topology. “Media Redundancy Protocol” (MRP) in Profinet and “Device Level Ring” (DLR) in EtherNet/IP networks are examples for test-frame based redundancy mechanisms which offer shorter recovery times. The “Parallel Redundancy Protocol” (PRP) according to IEC 62439-3 was designed for layer 2 networks to meet highest availability requirements due to its seamless redundancy. It realizes active network redundancy by packet duplication over two independent networks that operate in parallel.

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