10 tips for deploying EtherNet/IP, the ODVA Ethernet protocol
Plantwide deployment of EtherNet/IP Ethernet protocol requires an industrial network design methodology, which helps maintain real-time network performance, according to Cisco and Rockwell Automation.
It also helps enable convergence of multiple control and information disciplines, including: data collection, configuration, diagnostics, discrete, process, batch, safety, time synchronization, drive, motion, energy management, voice, and video (see Figure 1).
10 tips for EtherNet/IP implementation
- Understand a networked device’s application and functional requirements
- Enable a future-ready network design
- Create structure within the plantwide EtherNet/IP network
- Segment the logical topology into modular building blocks
- Use managed industrial switches
- Design and implement a robust physical layer reflecting availability and resiliency requirements
- Determine application and network security requirements
- Reduce network latency and jitter by using standard network protocols
- Increase control and information data availability
- Deploy a hierarchical network model using Layer 3 switches.
See more detail on each, below.
To design and plan this network, first consider each level of the logical model shown in Figure 2, and generate a network requirements document using industry best practices and standards, incorporating future expansion plans. Then inventory devices and applications with network dependencies within the logical model to help define a physical and logical topology for the requirements document. Implement the installation, procurement, and configuration of the network following the generated requirements document. Then audit the network against standards to help ensure that network requirements were met. To maximize network availability, manage change control and monitor the network to identify issues early. Assess network moves, additions, and changes as part of the change control process to protect the integrity of the requirements and performance of your network.
Here are details on the 10 industrial network design recommendations mentioned above.
1. Understand a networked device’s application and functional requirements. These include data requirements such as communication patterns and traffic types (industrial and non-industrial).
2. Enable a future-ready network design. To do this, utilize industry and technology standards, reference models, and reference architectures, such as the Rockwell Automation and Cisco Converged Plantwide Ethernet Architectures.
3. Create structure within the plantwide EtherNet/IP network. Develop a logical topology using a multi-tier switch hierarchy and the logical model shown in Figure 2. Define zones and segmentation, then place industrial automation and control system devices, servers, or other communicating end devices within the logical topology based on their location, function, availability, and performance requirements.
4. Segment the logical topology into modular building blocks. Create smaller Layer 2 networks to minimize broadcast domains. Use virtual local area networks (VLANs) within a zone to segment different traffic types, such as industrial and non-industrial. Minimize the number of devices to less than 200 within a zone and VLAN. Use firewalls to strongly segment the Industrial and Enterprise zones, creating a demilitarized zone that enables secure sharing of applications and data between the zones.
5. Use managed industrial switches. These provide key network services such as loop prevention, resiliency, segmentation, prioritization, time synchronization, multicast management, security, and diagnostics.
6. Design and implement a robust physical layer reflecting availability and resiliency requirements. Overlay the logical topology on the plant physical layout to create the physical topology. Use 1 gigabit-per-second fiber uplinks and redundant paths between switches for optimal network resiliency. Ensure the end devices and network infrastructure devices communicate at the best possible speed and duplex. Deploy physical cabling corresponding to plant conditions and requirements. In addition, deploy a defense-in-depth approach to help prevent noise coupling through techniques such as bonding, EMI segregation, shield barriers, and filtering.
7. Determine application and network security requirements. Establish early dialogue with IT, considering applicable IT requirements. Implement a defense-in-depth security approach at multiple application layers, such as physical, device, network, and application, using an industrial security policy (unique from and in addition to the enterprise security policy).
8. Reduce network latency and jitter by using standard network protocols. Protocols include time synchronization utilizing IEEE 1588 precision time protocol, quality of service for control data prioritization, and Internet Group Management Protocol for multicast management.
9. Increase control and information data availability. Implement a redundant path network topology such as a ring or redundant star. In addition, use a resiliency protocol to avoid Layer 2 loops while helping to ensure fast network convergence time. These considerations impact how quickly the network will recover from a disruption, which may result in application timeouts and system shutdowns.
10. Deploy a hierarchical network model using Layer 3 switches. Layer 3 switches support inter-VLAN routing between Cell/Area (Layer 2 network) zones and plantwide applications and servers. Layer 3 switch capabilities enable design recommendation 4. If the application requires industrialized Layer 3 switches, consider products such as the Allen-Bradley Stratix 8300 Layer 3 managed switch.
– Information provided by Rockwell Automation; edited by Mark T. Hoske, CFE Media, Control Engineering, www.controleng.com.
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