Parallel Redundant Protocol (PRP)

Transcription

1 Frequently Asked Questions This document answers questions the PRP functionality in the EIOC

2 Terminology This whitepaper answers questions about the Parallel undant Protocol (PRP) available in the Ethernet I/O card (EIOC) starting in v14.3. In this document, the following terminology is used. PRP: Parallel undant Protocol EIOC: DeltaV Ethernet I/O Card LAN A: Local Network A LAN B: Local Network B. Ethernet Device: Any Device that can talk an ethernet based protocol like Modbus TCP, OPC UA, EtherNet/IP, or IEC : A undant or device is used to connect single attached devices to a PRP network. What is PRP? PRP is a network protocol standard for Ethernet that provides seamless failover against failure of any network component. This redundancy is invisible to the application. Therefore, PRP can be enabled in the EIOC with any of the supported protocols. The way it operates is that the EIOC sends simultaneously two copies of a frame, one over each port (LAN A and LAN B). The two frames travel through their respective LANs until they reach a destination node. The destination node accepts the first frame of a pair and discards the second (if it arrives). Therefore, if one LAN is operational, the destination application always receives one frame. PRP provides zero-time recovery and allows to check the redundancy continuously to detect lurking failures. Where is PRP available in DeltaV? Starting in v14.3 PRP is only available in the EIOC with all the supported protocols. PRP is not available in the PK controller or the VIM 2 card in v

3 What is the supported architecture? DeltaV ACN Primary Secondary Firewall-IPD Industrial Networks Firewall LAN A LAN B Non-PRP Ethernet Device PRP Ethernet Device Figure 1 EIOC architecture with PRP When PRP is enabled, the Primary device network (LAN A) and Secondary Network (LAN B) become the same IP address and same MAC address since now both carry the same information. As we can see in Figure 1, when attaching Ethernet Devices to the device network, the devices need to support PRP to connect directly to LAN A and LAN B. If the device does not support PRP, then a needs to be used in the middle to convert PRP to a simplex network. Regular network switches can be used for building a PRP network. The Firewall-IP and Industrial Networks firewall in figure 1, are optional and highly recommended for cybersecurity purposes. The is only required with single attached devices or devices who do not support PRP. 3

4 What is a and when do I need it? When you want to connect devices that do not support PRP or is are single attached to the network (only has one ethernet port). The works by mirroring the LAN A frame published by a single attached device, and creates the LAN B frame from mirrored PRP messages to send to a single attached device. Who supplies a? There are many vendors of, Emerson has tested the Hirshmann 25 switches. Please consult the alliance program for detail and prices. What are the benefits of PRP? Ring topologies provide fault tolerant architecture, but not necessary give you availability. PRP gives you both, fault tolerance with redundant networks and the highest possible availability by providing interruption-free switchovers since it will take no time at all to switch over in failure situations. Naturally this applies only provided both networks do not fail simultaneously. Can I provide fault tolerant architecture with PRP for Motor Control Centers (MCCs)? DeltaV ACN LAN A LAN B MCC A MCC B Figure 2 MCCs with several single attached motor starters 4

5 Traditionally the motor control centers (MCCs) consist or several motor starters or variable speed drives that only have one port. Therefore, they need to be single attached to the network. As we explained earlier, when you enable PRP in the EIOC you can provide redundancy all the way from the EIOC to the MCC. Then by putting an, the EIOC will appear as one IP address and one MAC address for motor starters, they think they synchronize with only one master (see Figure 2). We need to mention that in this example the single point of failure still is the motor starter because it doesn t allow redundant communications. If you want to eliminate single point of failure, motor starters would have to support PRP natively. What is the licensing and how do I order PRP? There is no Licensing associated with PRP and it is included with the EIOC. This product and/or service is expected to provide an additional layer of protection to your DeltaV system to help avoid certain types of undesired actions. This product and/or service represents only one portion of an overall DeltaV system security solution. Emerson does not warrant that the product and/or service or the use of the product and/or service protects the DeltaV system from cyber-attacks, intrusion attempts, unauthorized access, or other malicious activity ( Cyber Attacks ). Emerson shall not be liable for damages, non-performance, or delay caused by Cyber Attacks. Users are solely and completely responsible for their control system security, practices and processes, and for the proper configuration and use of the security products. Emerson North America, Latin America: or Asia Pacific: Europe, Middle East: , Emerson. All rights reserved. The Emerson logo is a trademark and service mark of Emerson Electric Co. The DeltaV logo is a mark of one of the Emerson family of companies. All other marks are the property of their respective owners. The contents of this publication are presented for informational purposes only, and while diligent efforts were made to ensure their accuracy, they are not to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are governed by our terms and conditions, which are available on request. We reserve the right to modify or improve the designs or specifications of our products at any time without notice.