Rockwell Automation and
Cisco Four Key Initiatives:
•
Common Technology View:
A single system architecture, using open,
industry standard networking technologies,
such as Ethernet and IP, is paramount for
achieving the flexibility, visibility, and
efficiency required in a competitive
manufacturing environment.
•
Resilient Ethernet
Protocol in a Converged
Plantwide Ethernet
(CPwE) Architecture
White Paper
October 2014
Converged Plantwide Ethernet
Architectures:
These manufacturing focused reference
architectures, comprised of the Rockwell
Automation Integrated Architecture™
and Cisco’s Ethernet to the Factory,
provide users with the foundation for
success to deploy the latest technology
by addressing topics relevant to both
engineering and IT professionals.
•
Joint Product and Solution
Collaboration:
Stratix 5700™ and 8000™ Industrial Ethernet
switches incorporating the best of Cisco and
the best of Rockwell Automation.
•
People and Process Optimization:
Education and services to facilitate
Operational Technology (OT) and IT
convergence and allow successful
architecture deployment and efficient
operations allowing critical resources to
focus on increasing innovation and
productivity.
Document Reference Number: ENET-WP0033A-EN-P
Resilient Ethernet Protocol in a Converged
Plantwide Ethernet (CPwE) Architecture
White Paper
Introduction
The Converged Plantwide Ethernet (CPwE) architecture now includes a Resilient Ethernet Protocol
(REP) architecture, which supports switch ring topology resiliency for Industrial Automation and
Control System (IACS) devices and equipment. The REP release of CPwE is a collaborative effort of
Cisco Systems, Inc. and Rockwell Automation, Inc., reflecting the Information Technology (IT) and
IACS knowledge and expertise of both companies.
REP is suitable for many IACS applications that require a switch ring topology to meet application
availability requirements (Figure 1). IACS applications that can tolerate up to a 100 ms network
convergence recovery time are suitable for REP:
•
Controller to Human Machine Interface (HMI)
•
Controller to Controller
•
Controller to Input/Output (I/O)
•
Controller to Variable Frequent Drives (VFDs)
•
Controller to Motor Control Centers (MCCs)
For IACS applications that require a faster network convergence recovery time, Cisco and Rockwell
Automation recommend either a redundant star switch topology with the Flex Links resiliency
protocol or a device-level ring topology, such as the Open DeviceNet Vendors Association (ODVA)
Device Level Ring (DLR) (Figure1).
Resilient Ethernet Protocol in a Converged Plantwide Ethernet (CPwE) Architecture White Paper
ENET-WP0033A-EN-P
2
Resilient Ethernet Protocol in a Converged Plantwide Ethernet (CPwE) Architecture White Paper
Business Value of Resiliency in Converged Networks
Figure1
REP IACS Applications
Industrial
Zone
HMI
I/O
VFD
Drive
CIP Class 3
REP
IES
IES
CIP
Class 1
Class 3
IES
IES
Controller
I/O
Redundant
Controllers
IES
IES
DLR
DLR
HMI
CIP Class 1
Controller
CIP Sync
CIP Motion
VFD
Drive
VFD
Drive
Safety
Controller
I/O
Safety
I/O
I/O
Servo
Drive
296641
CIP Safety
Instrumentation
The REP architecture aligns with previous CPwE systems from an overall architecture framework
(Figure 2) perspective and with general design and implementation recommendations in order to
continue to align with industry standards. The REP architecture utilizes EtherNet/IP™ network
communications, which are driven by the ODVA Common Industrial Protocol (CIP).
Figure 2
REP Ring in CPwE
Distribution
Switches
Cell/Area Zone
Levels 0–2
REP
Deployment
Layer 2
Access Switch with
Resilient Ethernet
Protocol
HMI
Layer 2
Access Switch with
Resilient Ethernet
Protocol
HMI
REP
Deployment
Drive
Cisco IE Cell/Area #
(up to 24 switches)
Controller
Drive
RA STRATIX Cell/Area #
(up to 24 switches)
297582
Controller
Business Value of Resiliency in Converged Networks
Increasing numbers of devices are being connected on the plant floor. Such devices are being
connected using the same network technology as the Internet. Devices such as sensors
embedded in manufacturing devices that collect data are now used as tools to understand
complex processes better. With real-time data, manufacturers can respond to changes quickly.
REP-based architectures enhance the production network's resilience and ability to support
systems that connect people, processes, and data to real time applications, even during a network
disruption. In manufacturing, IP-based networks like EtherNet/IP drive a new generation of
connected, intelligent machines with improved network visibility into the plant—supported by the
Connected Enterprise vision from Rockwell Automation and Cisco's Internet of Everything (IoE).
Resilient Ethernet Protocol in a Converged Plantwide Ethernet (CPwE) Architecture White Paper
ENET-WP0033A-EN-P
3
Resilient Ethernet Protocol in a Converged Plantwide Ethernet (CPwE) Architecture White Paper
Unique Capabilities, Solving Manufacturing Challenges
•
Lower Costs—Placing network intelligence, such as REP, deeper into plants with ruggedized
but standard industrial internet protocol (IP) networks increases critical information access from
machines, resiliency for some applications, bandwidth, and troubleshooting abilities.
•
Improved Machine Uptime—Improved uptime of end-to-end IP networks can speed up the
troubleshooting of issues with plant floor machines. By leveraging improved network uptime,
visibility down to the machine can be improved while troubleshooting time can be greatly
reduced.
Unique Capabilities, Solving Manufacturing Challenges
Using REP, network resiliency is established within the manufacturing environment at the network
protocol level, forming a switch-level ring redundant path topology. Because REP is distributed
across the switch ring, the protocol does not rely on a master node or master switch to control the
ring's status or state. Because of the nature of a ring topology, segment failures are detected locally
through loss of signal (LOS) or loss between connected neighbors. REP, when used in combination
with a ring topology, provides simple and effective redundancy. The CPwE architecture utilizes the
Industrial Ethernet Switch (IES) models, including the Allen-Bradley Stratix 5700™ and Stratix 8000™
series, and the Cisco Industrial Ethernet (IE) 2000 and 3000 switches, all of which support REP. The
Cisco Catalyst 3750-X supports REP as the distribution switch, as shown in Figure 3.
•
Efficient Network—REP utilizes a Layer 2 ring topology utilizing up to 24 Allen-Bradley Stratix
5700 / Stratix 8000 Series switch devices in a given ring. REP allows for efficient network
re-convergence times, when compared to more traditional methods such as the Spanning Tree
method. Moreover, this mechanism for resilient failovers remains flexible and supports fast
convergence when scaling the ring's size.
•
Redundancy in a Ring Topology—By definition, a REP segment is a chain of ports connected
together. Each end of a network segment terminates at a neighboring switch or at the
Distribution Catalyst 3750X Series switch. Figure 3 illustrates a simple REP segment.
Figure 3
REP Segment Example
Catalyst 3750-X
or IES
Edge
Port
Edge
Port
IES
IES
Alternate
Port
REP Segment
IES
IES
PAC
IO
IES
IES
Drive
IES
IO
IO
Drive
296655
HMI
REP intelligence prevents the creation of a traffic loop condition when a ring of the Stratix
5700/8000 series switches is utilized. If a cable breaks or switch service disrupts, REP allows CIP
traffic to continue to reach the edge of the ring topology for IACS, monitoring, and management
continuity.
Resilient Ethernet Protocol in a Converged Plantwide Ethernet (CPwE) Architecture White Paper
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ENET-WP0033A-EN-P
Resilient Ethernet Protocol in a Converged Plantwide Ethernet (CPwE) Architecture White Paper
Summary
Summary
REP establishes a resilient network architecture that goes beyond previously explored resiliency
protocols. REP is the only ring switch-level resiliency protocol applicable to both Industrial
Automation and IT applications. As plant network convergence drives significant change in
manufacturing organizations, systems, and networks, REP improves network convergence. In the
event of a network disruption, REP networks support continued IACS functionality and reduced
downtime costs, while preserving throughput productivity and sustained operations. Applications
deployed in a REP environment support a wide variety of manufacturing disciplines, including
batch, discrete, process, and hybrid manufacturing. Cisco Systems and Rockwell Automation's test
and validation of REP within the CPwE architecture builds upon established standards, while
expanding network resiliency functionality.
The Cisco Validated Design (CVD) for Deploying a Resilient Ethernet Protocol in a Converged
Plantwide Ethernet System is accessible from:
•
http://www.cisco.com/c/en/us/td/docs/solutions/Verticals/CPwE/REP/CPwE_REP_DG.html
•
http://literature.rockwellautomation.com/idc/groups/literature/documents/td/enet-td005_-en-p.
pdf
Cisco is the worldwide leader in networking that transforms how people connect, communicate and collaborate. Information about Cisco can be found at www.cisco.com. For
ongoing news, please go to http://newsroom.cisco.com. Cisco equipment in Europe is supplied by Cisco Systems International BV, a wholly owned subsidiary of Cisco
Systems, Inc.
www.cisco.com
Americas Headquarters
Cisco Systems, Inc.
San Jose, CA
Asia Pacific Headquarters
Cisco Systems (USA) Pte. Ltd.
Singapore
Europe Headquarters
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www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)
Rockwell Automation is a leading provider of power, control and information solutions that enable customers to get products to market faster, reduce their total cost of
ownership, better utilize plant assets, and minimize risks in their manufacturing environments.
www.rockwellautomation.com
Americas:
Rockwell Automation
1201 South Second Street
Milwaukee, WI 53204-2496 USA
Tel: (1) 414.382.2000, Fax: (1) 414.382.4444
Asia Pacific:
Rockwell Automation
Level 14, Core F, Cyberport 3
100 Cyberport Road, Hong Kong
Tel: (852) 2887 4788, Fax: (852) 2508 1846
Integrated Architecture, Stratix 8000, Stratix 5700, ControlLogix, FLEX I/O, POINT I/O, CompactLogix, Studio 5000
RSLogix 5000 are trademarks of Rockwell Automation, Inc. Trademarks not belonging to Rockwell Automation are
property of their respective companies.
© 2014 Cisco Systems, Inc. and Rockwell Automation, Inc. All rights reserved.
Europe/Middle East/Africa:
Rockwell Automation
NV, Pegasus Park, De Kleetlaan 12a
1831 Diegem, Belgium
Tel: (32) 2 663 0600, Fax: (32) 2 663 0640
Publication ENET-WP0033A-EN-P October 2014