Time Sensitive Networks - Update from the IIC
Testbed for Flexible Manufacturing
Paul Didier
Manufacturing Solution Architect
Cisco Systems
Rick BlairPrincipal Network System Architect
Schneider ElectricPresented at the ODVA2018 Industry Conference & 18th Annual Meeting
October 10, 2018
Stone Mountain, Georgia, USA
Abstract
The IIC’s TSN for Flexible Manufacturing testbed looks to enable Industrial IoT and Industrie 4.0 throughdeployment of open, standard, deterministic networks within production facilities. The goal is to display
the value and readiness of Time-Sensitive Networks (new IEEE standards) supporting real-time control &synchronization of high performance machines.
The testbed is over 2 years old. There are over 25 companies participating, with 12 plugfests conducted,
2 testbed instances established, 2 demonstrators developed, an OPC UA Pub/Sub data exchange
outlined and a whitepaper on industrial traffic type characterization and mapping produced. This paper
will give an update on the testbed’s activities, an outlook on the readiness of TSN as a technology andindication where further work is required from the testbed perspective. In addition, we will review theIndustrial Automation traffic type characterization and TSN function mapping coming from the Testbed.
As a point, the IIC invites all ODVA members to participate in the activities – without the need to be an IICmember.
Introduction: Industrial Internet Consortium TSN for Flexible Manufacturing Testbed
The Testbed’s vision is to enable Flexible Manufacturing for Industrial IoT and Industrie 4.0 throughdeployment of open, standard deterministic networks within production facilities. Its goal is to display thevalue and readiness of Time-Sensitive Networks (new IEEE standards) supporting real-time control &synchronization of high performance machines. Testbed activity is driving accelerated market adoption ofthis critical IIOT/Industrie 4.0 technology
The TSN Testbed is enabling the early phase usage of enhancements to Ethernet standards IEEE 802.1
and IEEE 802.3. All TSN Testbed work is communicated to IEEE and Avnu, a standards organization
developing the interoperability and certification based on the IEEE’s TSN. It is used to display OPC UA
enabled vendor independent interoperability of real-time data and other industrial automation protocols(e.g. ODVA’s EtherNet/IP) on the same network with typical IT voice/video data.

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Participation in IIC’s testbeds does not require IIC membership, but does require some basic approvals(e.g. NDAs). Therefore any ODVA member can participate without being an IIC member or giving
financial contributions.
Key activities of the Testbed include:-----Conducting Plugfests where participants can learn about TSN and conduct tests of indevelopment or available product with a variety of other companies, including chip, end-device,network and testing vendors. The plugfests focus on a range of TSN features including but notlimited to:o Time synchronizationo Communicating scheduled traffic (IEEE 802.1Qbv)
o TSN Configuration and Managemento Frame Preemption (IEEE 802.1Qbu and IEEE 802.3br)Plugfests are conducted in either the US-instance (NI Headquarters, Austin TX) or ISW(University of Stuttgart, Stuttgart Germany).
Developing TSN Demonstrators that are used to display the capabilities of TSN and the results ofthe Testbed activities at major shows (e.g. SPS IPC Drives, Hannover Messe, IMTS, IoT
Solutions World Congress, etc.)
Developing an Interoperability Rack in each testbed location for the permanent installation of aTSN system for ongoing and long-term testing. The interoperability racks are internet accessible
via established Firewalls/VPN.
Conducting updates and discussions on a variety of TSN and relevant standards development
activities. In this way, companies participating do not need to join all the relevant standards
groups to stay abreast of developments and to provide feedback to those efforts.
Collaborating with relevant standards and consortia including: IEEE, IEC, AVNU, OPC
Foundation, LNI4.0, and ODVADevelop marketing and technical material to assist with the above, including press releases, aMarketing Brochure, arranging Press/Analyst interviews, articles (e.g. Journal of Innovation) andwhitepapers.

The testbed currently has over 25 regular participants.

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Testbed Status
Below is a summary of the Testbed status.

Overview of IIC TSN for Flexible Manufacturing
Key Facts:• > 25 Vendors participating (chip makers, switches, automation devices
and testing products)• > 10 Plugfests conducted over the last year in US, Austria and Germany• 2 Testbed locations at NI in Austin TX and at ISW in Stuttgart Germany• 2 Best Testbed Awards: 1st IIC Testbed Showcase (Q1 2017) and IoTSolutions World Congress (2017)• Demonstrations at 6 major shows: IOT SWC, SPS Drives, Hannover
Messe, NI Week, IOT World, DE Forum• Collaboration with multiple standardization bodies: IEC, IEEE, IETF,
AVNU, LNI4.0, OPC and ODVA
Investigated in testbed subgroup:1.
Selection of communication characteristics for Industrial Automation and Control Systems
2.
3.

Identification of traffic types with common requirements
Mapping of Ethernet Qos/TSN mechanisms to traffic types
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4

Traffic Types in Converged Industrial Network Whitepaper
A key output of the TSN Testbed activity relevant to the ODVA is the testbed’s whitepaper on Descriptionof Converged Traffic Types. The document describes application traffic types that are found in industrial
and process control systems and therefore are supported in the Industrial Internet Consortium’s Time
Sensitive Networks for Flexible Manufacturing testbed, including different types of critical control trafficand other traffic that may be in a manufacturing network. The IEEE 802.1Q specification, Annex I lists
traffic types as a means to structure network transmission priority and packet drop preference. This paperenhances those traffic types by adding types found in typical manufacturing Industrial Automation andControl Systems (IACS), with a list of characteristics to describe them precisely. In a draft enhancement,
it then identifies IEEE 802.1 TSN mechanisms to support these traffic types in a converged network.

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Traffic Type Characteristics are depicted below:

Traffic Type Characteristics
Application-derived communication requirements
Traffic Type

Description

Data Transmission Periodicity• Cyclic/periodic• Acyclic/sporadic - also periodic frames with large periods (1-2 seconds)

PeriodPlanned data transmission interval (“cycle”), range in orders of magnitude of time

Synchronized to network

Indication whether application is synchronized to network time (yes or no)

Data delivery guarantee• Deadline: data delivery of each packet in a stream is guaranteed to occur at all registered receivers ator before a specified time (within a communication cycle)• Latency: data delivery of each packet in a stream is guaranteed to occur at all registered receivers
within a predictable timespan starting when the packet is transmitted by the sender and ending when
the packet is received• Bandwidth: data delivery of each packet in a stream is guaranteed to occur at all registered receivers
if the bandwidth utilization is within the resources reserved by the sender

Tolerance to interference

Application’s tolerance of a certain amount of latency variation of the packet’s transmission (i.e. jitter)

Tolerance to lossApplication’s tolerance to a certain amount of consecutive packet loss in network transmission

Data size

Application payload size to be transmitted (fixed or variable)

Criticality

Criticality of the application data for the operation of the critical parts of the system (high, medium, low)

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5A summary of the Traffic Types and their characteristics is depicted below:< 2ms

Tolerance toloss

Periodic

Datadelivery
guarantee

Tolerance tointerference

Isochronous

TypicalPeriod

Synchronizedto network

TypesPeriodicity

Traffic Types for Industrial Automation and Control Systems

Yes

Deadline

0None

Fixed: 30 - 100 Bytes

HighFixed: 50 - 1000 Bytes

HighHigh

Typical application datasize

Criticality

CyclicPeriodic

2 - 20ms

No

Latency<= latency

1-4Frames

EventsSporadicn.a.

No

Latency<= latency

Yes

Variable: 100 - 1500 Bytes

Network Control

Periodic

50ms - 1s

No

BandwidthYes

Yes

Variable: 50 - 500 Bytes

High

Config & Diagnostics

Sporadicn.a.

No

Bandwidthn.a.

Yes

Variable: 500 - 1500 bytes

MediumBest Effort

Sporadicn.a.

NoNonen.a.

YesVariable: 30 - 1500 Bytes

Low

VideoPeriodic

Frame RateNo

Latencyn.a.

Yes

Variable: 1000 - 1500 Bytes

Low

Audio/Voice

Periodicn.a.

No

Latencyn.a.

Yes

Variable: 1000 - 1500 Bytes

Low

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Table of applied TSN Mechanisms
Mechanism

Description and Comment

IEEE 802.1Q

Strict Priority Forwarding
Strict Priority Forwarding suggests that packets are assigned to outbound queues
identified by a Traffic Class. The traffic classes are all prioritized in this way.

IEEE 802.1Qav

Forwarding and Queuing Enhancements for Time-Sensitive Streams – Credit
Based Shaping
This mechanism ensures traffic types receive requested bandwidth over other lower
priority traffic types, but does not meet other Data Delivery Guarantees outlined. It
was particularly designed for Audio/Video traffic types. Credit-based Shaping queues
can also be used to limit a traffic type’s use of bandwidth as the credit is only
replenished over a certain amount of time. When Scheduled Traffic is introduced,
these bandwidth guarantees are not achievable to the same degree as independently.

IEEE 802.1ASRev

Timing and Synchronization for Time-Sensitive Applications
Clock synchronization is required to support scheduled traffic (IEEE 802.1Qbv) andCredit-based shaping ensuring that the network infrastructure and end devices cantransmit on a schedule based on a common sense of time. Therefore in the mapping
considerations, it receives the same recommendation type as Scheduled Traffic. It
should be noted that the IACS applications often require time synchronization, but thatconsideration is not reflected in the mappings.

IEEE 802.1Qbv

Enhancements for Scheduled Traffic
This enhancement enables traffic streams to be communicated in the network without
interference and with little or no jitter. This feature can be used to meet all the datadelivery guarantees: deadline, latency and bandwidth.

IEEE 802.1Qbu& IEEE 802.3br

Frame preemption
Frame preemption has two key capabilities. First, in the absence of traffic scheduling(802.1Qbv), frame preemption can be used to reduce latency and jitter of packet
transmission to help meet deadline and latency data delivery guarantees for express
frames in the presence of potentially interfering preemptible frames. Second, in thepresence of traffic scheduling, frame preemption is beneficial to lower priority
preemptible traffic by freeing utilizable bandwidth for transmission.

IEEE 802.1Qcc

Stream Reservation Protocol (SRP) Enhancements and Performance
Improvements
SRP contains multiple signaling protocols. This enhancement adds the Multiple
Stream Registration Protocol (MSRP) as a signaling protocol that enables the ability
to reserve network resources for devices that will guarantee the transmission andreception of data streams across a network with the requested QoS capability. Theseend stations are referred to as Talkers (devices that produce data streams) andListeners (devices that consume data streams). This mechanism is used to provide
consistent QoS behavior across the network.

IEEE 802.1CB

Frame Replication & Elimination for Reliability
This mechanism supplies a critical function for industrial networking systems –seamless redundancy from connection or network infrastructure outage. It isconsidered an optional mechanism for critical applications where the network topology
supports redundant, non-congruent paths.
Additionally, this protocol contains specifications for Stream Identification. For ingresspolicing (Rate or Time-based) on Stream ID is mandatory, this part of the specificationis also required.

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Mechanism

Description and Comment

IEEE 802.1Qci

Per-Stream Filtering and Policing (a.k.a. Ingress Policing)This mechanism referred to as per stream filtering and policing (PSFP), is used tofilter/police ingress frames that do not meet the specified policies as configured on therelevant managed objects. PSFP is supported by the following policing actions:• Time-based policing. This is supported by the Stream Gate Instance. Thisidentifies the details of the of the time gate parameters. This allows detection ofincoming frames during time periods when the stream gate is in the closed state
to result in the stream gate being permanently set to a closed state, until such atime as management action is taken to reset the condition. The intent is to support
applications where the transmission and reception of frames across the network iscoordinated such that frames are received only when the stream gate is open,
and hence, a frame received by the stream gate when it is in the closed state
represents an invalid receive condition [IEEE 802.1Q §8.6.5.1.2]. The Stream
Gate Instance applies to one or more Streams• Rate-based policing. This is supported by the Flow meter instances. This allows tospecify the Committed Information Rate, and Excess Information Rate. These
meters apply to specific one or more streams, and allow policing of streams thatexceed the configured rate.
This mechanism is used to protect queues from unwarranted traffic and maintain theestablished quality of service for specified traffic and streams. The recommendations
below include a type of policing to be applied.

Below is a summary table of the Traffic Types mapped to TSN Mechanisms

M

OO

Cyclic - Option: Strict priority

M

5

Cyclic – Option: Scheduled TrafficM

5

Events - Control

M

4

Events - Alarms & Operator Commands

M

3M

M

MTM

O

MR

M

MRM

O

MR

M

O

MR

O

MR

RO
O

M

Config & Diag.

M

2Network Control

M

7Video, Audio, VoiceM

1

OBest Effort

M

0O

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6

Reservation/Scheduling802.1CB – FrameReplication

M

802.1Qav – CreditBased Shaping

Cut-Through6802.1Qci – Time-based
Ingress Policing

802.1AS-Rev ClockSynch

M

802.1Qbu – FramePreemption

802.1Qbv (exclusivegating)

Isochronous

Traffic Class

Types

802.1Q
Strict Priority

Summary of Mappings

O*M
M

CMRRM

Legend:•M - Mandatory••••

O - Optional
C – Conditional
R –Recommended
T– Time-based••

R– Rate-based* - End devices

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References (optional)
IIC’s TSN Testbed for Flexible Manufacturing whitepaper Description of Converged Traffic Types:
https://www.iiconsortium.org/pdf/IIC_TSN_Testbed_Traffic_Whitepaper_20180418.pdf
IIC’s Journal of Innovation, January 2017: https://www.iiconsortium.org/news/joi-articles/2017-JanResults-Insights-Best-Practices-from-TSN-Testbed-I.pdf
IIC’s Testbed: TSN for Flexible Manufacturing: https://www.iiconsortium.org/time-sensitive-networks.htm
IIC’s TSN Testbed Brochure: https://www.iiconsortium.org/pdf/TSN-brochure-8-22-18.pdf*****************************************************************************************************************************************************The ideas, opinions, and recommendations expressed herein are intended to describe concepts of the author(s) for the possible useof ODVA technologies and do not reflect the ideas, opinions, and recommendation of ODVA per se. Because ODVA technologies
may be applied in many diverse situations and in conjunction with products and systems from multiple vendors, the reader andthose responsible for specifying ODVA networks must determine for themselves the suitability and the suitability of ideas, opinions,and recommendations expressed herein for intended use. Copyright ©2018 ODVA, Inc. All rights reserved. For permission toreproduce excerpts of this material, with appropriate attribution to the author(s), please contact ODVA on: TEL +1 734-975-8840
FAX +1 734-922-0027 EMAIL odva@odva.org WEB www.odva.org. CIP, Common Industrial Protocol, CIP Energy, CIP Motion, CIP
Safety, CIP Sync, CIP Security, CompoNet, ControlNet, DeviceNet, and EtherNet/IP are trademarks of ODVA, Inc. All othertrademarks are property of their respective owners.

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