Enhancements to EtherNet/IP for Constrained Devices andNetworks

David D. Brandt: Rockwell Automation, Inc.
Dayin Xu: Rockwell Automation, Inc.
Dr. Jörg Hähniche: Endress+Hauser Process Solutions AGMatthias Dietrich: Endress+Hauser Process Solutions AGOctober 10, 2018

Purpose of Paper

This paper presents a set of proposed enhancements,
many adopted from or inspired by IETF and IEEE,
making it possible to use EtherNet/IP on constrained
devices and networks, thus enabling the single-network
vision - where all devices in an industrial plant cancommunicate with the same set of protocols.

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ODVA Community Interest•••ODVA Conference Papers have expressed interest in support for better
addressing constrained devices
2014 – 2017
Various applications:– Process Automation– In-Cabinet components•••

Wired and wirelessConsidering usage of emerging technology
See [1-6]

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Industrial Network Convergence
Industrial Ethernet has
exhibited rapid growth,with EtherNet/IPemerging as a leader.
Fieldbuses (and sensornetworks) still retain alarge position and manypotential network nodes
remain hardwired.
Source: HMS networks, Feb 2018
(Parentheses indicate 2017 numbers)

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4The Single Network Vision
End users understand andseek the advantages of aharmonized network - basedon Ethernet, IP, and therelated open ecosystem.

Single network advantages include:
Higher performance for a similar costElimination of costly applicationspecific gateways

Leverage of a large existing
ecosystem (protocols, security,network switches, etc.)

Reduced installation, maintenance,and management complexity

Simplified integration with cloudapplications



Reduced interoperability issues

Organizations promoting Ethernet and IP to the edge
(See backup slide)

OPEN
Alliance

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IEEEDigitalCeiling

IETF
APL

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Barriers to the “Single Network Vision”
•••••
•••
•

Cost adderComponent footprint
Power consumption
System wiring complexity
Cable distance
Network power solution
Intrinsic Safety compatibility
Low power wireless solution
Protocol complexity

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The mix of Industrial Ethernet,
fieldbuses, and hardwired
nodes persists due toapplication constraints near
the network edge.

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IETF: Constrained-Node Networks
 Constrained Node characteristics:
 Low cost
 Small size Limited memory [Flash,RAM], and processing
resources
 Limited power and energy[battery size or scavenging] Limited upper layer services
 Low weightConstrained Network characteristics:
 Low bitrate or throughput
 High packet loss Variability delivery rate Asymmetric traffic Small packet size Limited availability [devicesleeps]
 Limited upper layer services“Terminology for Constrained-Node Networks” in https://tools.ietf.org/html/rfc7228

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IETF: 6TiSCH Standards••

Enhancements for Constrained Nodes and Networks
Applicable to both low power wireless and wired networks•

Features:–––––

Eliminates TCP overhead (UDP-only)
Compresses messages
Expands the address space (IPv6)
Optimizes security (OSCORE)
Shrinks the Web server (CoAP)

IETF suite of IP standards solving IoT needs (similar to Fieldbus needs)
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88IEEE Single Pair Ethernet(s)Industrial Automation
Building Automation

IEEE 802.3cg

Lighting• Communication andoptional power over a
single pair
• Reduction in wiring, nodecost, size, and power
consumption

Automotive
ElevatorsData Center
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Numerous industries sought
Ethernet enhancements todisplace edge networks.

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9IEEE: Emerging SPE
 IEEE P802.3cg 10 Mbit/s SPE (Estimated 2019) 10BASE-T1L

Targeted at process automation instruments
1000 m, intrinsic safety compatible, legacy wiring

Addresses longdistance

10BASE-T1STargeted at replacing:CAN, CAN FD, MOST and FlexRay in automotive
Hardwiring for in-cabinet components for industrial automation
I2C and SPI in data centers

25 m multidrop option
Determinism by PHY-level Collision Avoidance (PLCA)

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Addresses low cost
control

10Constrained EtherNet/IP application areas
Enterprise
Systems

IT, Cloud

Manufacturing
Systems

Automation
Servers

Supervisory
Control

PAC/PLC/DCS

BasicControl
Field
Devices
Constraints

PAC/PLC/DCS

PAC/PLC/DCS
Cost,
size,
power

#wires,size,
power

100BASE-TX and 1000BASE-T
10BASE-T1S multi-drop
TBD SPE
10BASE-T1L, 1000m, Ex e
10BASE-T1L, 200m, Ex i
6TiSCH + 802.15.4e

PAC/PLC/DCS
Power vs.
cable size
& length

PAC/PLC/DCS

Battery,rate,
packet size

Intrinsicsafety,power

In-cabinet
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Process Automationwww.odva.org

Low-power Wireless
11UDP-only option

UDP-only option•Problem:– EtherNet/IP requires both TCP andUDP– TCP presents substantial overhead
for constrained MCU limited Flashand RAM– “Chatty” TCP messaging reduces
battery life in low power wirelessdevices•

Related Problem:– CIP Security requires both TLS andDTLS•

Solution:– Add optional supportfor UDP-only andDTLS-only.

•TLSDTLSTCPUDPBenefits:– Use smallest MCUs
• UDP-only prototype shows 30%
savings in Flash and RAM– Draw enhancements from othersources• Emerging IoT stacks like IETF
CoAP rely on UDP exclusively
13

Simplified UDP-based Messaging• ListServices identifies
capability

Existing EtherNet/IP
Simplified EtherNet/IP– UDP-only or TCP+UDPor Both• No TCP connections• No encapsulation
sessions• No bindings between
TCP connections andEtherNet/IP sessions
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TCP-based
Forward_Open

Messageand stackcomplexity
is reduced

TCP-based
Forward_Close

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Proposal•••

Support both secure and standard UDP-only
Extend for full set of services
Develop a unified capability discovery method

Existing
Volume 8Secure
UDP-only

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Encapsulation and CPF
Header Compression option

Encapsulation and CPF header compression option•

Problem:•– Compress EtherNet/IP
encapsulation and CPF headers bywell known (IETF 6TiSCH)
techniques– EtherNet/IP Encapsulation andCPF headers message overhead issignificant for low power wirelessnetworks• Lossless “eliding” of header fields
and options that rarely change• Added bits indicate the optionalpresence of byte or word fields(> 8:1 compression)• E.g., IETF 6TiSCH = 127B max.
• Wireless constrains packet size toincrease battery life

– Large messages either cannot besent or must be fragmented into
multiple packets• Reduces battery life and increases
latency

Solution:•Benefits:– Increase battery life and reduce
latency for low power wireless17

Proposal
Evaluate Optional Compressions
Prototype Examples
HeaderCompress15
ion and14
Comman13d (HCC)
12,11
10
98
Bit7-0CPF
Compress 15
ion&Item
14Count
13,12(CCIC)
11,10
9,8
7,6
5,4,3
2,1,0

Word ValueHeader Comp. Flag
ReservedOptions
Sender Context
StatusSession Handle
LengthCommand
Word ValueGeneral
ListIdentity ListService UCMM Class0/1
0xB7630xBF040xB76F
10121110x6F0x80520x8092

CPF Comp. Flag

11Message TypeReserved0000T->O Socketaddr
O->T Socketaddr
Data Item
Address Item
Item Count00122002224081810Before compression (byte)
After compression (byte)

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10121110x63

244

10131110x04

242••
•
•

Encapsulation header
CPF for Class 0/1
CPF for UCMM
CPFs used within CIP services•MultipleItems

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•

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Replaces and shrinks
Encapsulation header
Could be reduced further18

Constrained EtherNet/IP
Physical Layers

Constrained EtherNet/IP Physical Layers•

Problem:•– EtherNet/IP does not support
appropriate physical layers forseveral constrained application
areas:
1.
2.
3.

Process Automation wired
instruments for APL
Process Automation companion
wireless instruments
In-cabinet components

Solution:– Reference and extend 3 new PHYs:
1.
2.
3.

•

IEEE P802.3cg 10BASE-T1L PHY
IEEE Std 802.15.4-2015 PHY
IEEE P802.3cg 10BASE-T1S PHYBenefits:– Support important constrained
EtherNet/IP application areas

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Constrained EtherNet/IP
Communication Profile

Constrained EtherNet/IP Communication Profile•

Problem:– EtherNet/IP does not support
constrained device and network
requirements•

Solution:– Develop a constrained EtherNet/IP
communication profile

Communication Profile

Required:• UDP-only• Minimum objects• UCMM and Class 1 only
• Simplified Connection
Manager object
Optional:• DTLS-only security• Encapsulation header
compression• IPv6 mapping

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Minimum device object model•

Same base objects for constrained
EtherNet/IP, but minimizeimplementation of base objects•Optional compression of Encapsulation
and CPF headers•

Minimized CIP transports over UDP– UCMM + Class 1 onlyTechnical Track© 2018 ODVA, Inc.

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Object minimization example - Connection Manager
Original Definition in
EtherNet/IP Specification

Simplified Implementation forConstrained Devices

Object level simplifications
20 optional attributes

Zero attributes

4 common services

Zero common services

8 object specific services

2 object specific services (Forward_Open andForward_Close)

Service level simplifications
Class 0 and 1 I/O connection

Class 1 I/O connection

Unicast and multicast

UnicastClass 2 and 3 explicit connection

No explicit connection, UCMM only

CIP Routing

No CIP Routing

Listen-only or redundant owner

No redundancy

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24Constrained EtherNet/IP Capability CPF Item•

New “Constrained EtherNet/IPCapability” CPF item
– Discover constrained device’s
EtherNet/IP capability using
ListIdentity•New EDS entry [ConstrainedEtherNet/IP Capability]– Describe constrained device’sEtherNet/IP Capability

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Field
Type ID

Constrained EtherNet/IP Capability

LengthLink Type

0 = Ethernet
1 = 802.15.4e

TCP/IP TypeTBD (future compression or featurereduction capabilities)

Encapsulation &CPF Compression

WORD1: ENCAP Header Compression Profile
WORD2: CPF Compression Profile

CIP Transport
Type

Bit 0 = UCMM
Bit 1 = Class 1

CIP Application
TypeBit 0 = Active Report Manager

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Constrained EtherNet/IP over
6TiSCH Network
9-2 Data Link Layers
Though this specification is called “EtherNet/IP”,
Ethernet is technically not required. The EtherNet/IP
protocol may be used on any media that supports thetransmission of the Internet Protocol.

Constrained EtherNet/IP over 6TiSCH Network•

Problem:– EtherNet/IP does not have a low
power wireless option••Benefits:– Complements wired Process
Automation (under APL)

Proposed Solution:– Specify necessary enhancements for
EtherNet/IP over 6TiSCH:• Leverage proposed constrained
EtherNet/IP enhancements• Add 802.15.4 MAC and PHY• Add 6TiSCH router and network
management objects• IPv4/6 mapping to integrate 6TiSCH
devices into IPv4

A full IPv6 solution would bebeneficial, but is not proposed27

Motivation for IETF 6TiSCH••

Simplified 6TiSCH Stack

Open (not industry specific) wirelessstandard

Application Protocols:
CoAP /OSCORE

IP-based communication
6LoWPAN
ND

Optional DTLS•

Self-organizing mesh network– Robust, reliable, less engineering•

RPL

ICMPv6UDP

IPv66LoWPAN HC / 6LoRH HC

The market leader:– “By 2023, there will be 4.5 billion
802.15.4 mesh devices sold worldwide.”•Technical Track© 2018 ODVA, Inc.

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6topIEEE Std 802.15.4e TSCH (MAC)

IEEE Std 802.15.4 (PHYs)
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Prototype: Important Enhancements for Integration ofConstrained EtherNet/IP over 6TiSCH
Complex Integration

No
EtherNet/IPchanges

Constrained
EtherNet/IP
Simplifies
integrationand enables
security
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EtherNet/IP
ClientEncap. Header Compression
TCP <-> UDP-only
IPv4 <-> IPv6
UDP, IP <-> 6LoWPAN
Ethernet <-> 802.15.4e
Proxy +
6LoWPAN BorderRouter (6LBR)

EtherNet/IP
IPv4

Wireless Mesh Network
Constrained
EtherNet/IPover 6TiSCH (IPv6)

IPv4 <-> IPv6
UDP, IP <-> 6LoWPAN
Ethernet <-> 802.15.4e
EtherNet/IP
ClientEtherNet/IP
IPv4 + UDP-only+ CPF Compression

6LoWPAN BorderRouter (6LBR)

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Wireless Sensor
Node (WSN)

Wireless Mesh Network
Constrained
EtherNet/IPover 6TiSCH (IPv6)

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Wireless Sensor
Node (WSN)

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Security for Constrained EtherNet/IP over 6TiSCH••CIP end-to-end security is precluded by any 6LBR processing of the application layer(Encapsulation Layer compression)
6TiSCH requires IETF OSCORE security for network join, DTLS has some increase inoverhead
Link Layer Security is
REQUIRED by IETF

EtherNet/IP Security
Extended to 6LBR
2 separate
security
systems

EtherNet/IP
Client

6LoWPAN
Border Router(6LBR)

Wireless
Sensor Node(WSN)

6LoWPAN
Border Router(6LBR)

Wireless
Sensor Node(WSN)

EtherNet/IP Security
Extended to WSN
CIP Security
end-to-end

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New objects for 6TiSCH Network•

804.15.4 link object– In both 6LBR and WSNs
– Similar to Ethernet: Interface Speed, Flags, Counters,
State, Label, Capabilities, Physical Address…
– New: RF characteristics

•802.
15.4

6TiSCH wireless network management object–––––

In 6LBR
Network status information
Network topology information
Network routing information
Device join and leave

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Stack Summary

Constrained EtherNet/IP Stack
Eliminated
ModifiedNew

Unmodified

Optional attributes andservices, multicast, CIP
routing

CMClass3

UCMM

SessionTCP ENCAP
TLS

ListIdentity
ListServices

2221/TCP

44818/UDP

2222/UDP

802.
15.4

IPv4/6 Mapping

Class 1

UCMM+CL1 only
Encap. Header and
CPF Compression

DTLS

DTLS-only

2221/UDP

UDP-only

IPv4

6TiSCH

802.3

802.15.4e MAC

10BASE-T1S

10BASE-T1L
Wired

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6T

UDP ENCAP

Capability CPF

CM: Connection Manager Object
MR: Message Router Object
AR: Active Report - related Objects
TCP: TCP/IP Object
EN: Ethernet Link Object
6TiSCH: IPv6 over the Timeslotted Channel Hopping (TSCH)
mode of IEEE802.15.4e
6LBR: 6LoWPAN Border Router for 6TiSCH

ENMR

UCMM

6LBR
ProfileAPP nTCP

AR
Objs.

44818/TCP

APP 2

APP 1

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802.15.4 PHY

EDS- Capability- 802.15.4- 6LBR

Modifiedor newLinks

Wireless
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THANK YOU

References
1. IEEE 802.3cg (10SPE) – 10 Mb/s Single Pair Ethernet Meeting Industrial
Automation Objectives : 2017-ODVA-Conference_Brandt Xu Haehniche_IEEE802-3cg-10SPE_R0_FINAL
2. DeviceNet of Things - Use Cases, Value Proposition and Status of Specification:
2017-ODVA-Conference_Caspers_DOT_FINAL
3. Resource-constrained Industrial Things - Proposal for the Adaptation of CoAP to
EtherNet/IP: 2017-ODVA-Conference_Green Otterdahl_CoAP_FINAL
4. EtherNet/IP to the Edge – A Concept for "Low-complexity Ethernet” : 2017ODVA-Conference_Alsup_Weingartner_Low-complexity_Ethernet_FINAL
5. Extending EtherNet/IP™ to Resource-Constrained Industrial Things:
2015_ODVA_Conference_Xu-Brooks_Extending-EtherNetIP-to-ResourceConstrained-Industrial-Things-FINAL
6. CIP over 6LoWPAN: Expand CIP to IPv6-based Field Wireless Network:
2014_ODVA_Conference_Xu_Brooks_Yu_Brandt_CIP_over_6LoWPAN_FINAL
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Outside efforts related to expanding
Ethernet and IP to edge devices•••••

OPEN Alliance: One Pair EtherNet Alliance, Automotive industry
organization focused on the all-Ethernet car
Digital Ceiling: LED lighting connected and powered by Ethernet with PoE,
augmented by sensors and wireless communication
IEEE: Standard for Single Pair Ethernet for Automotive, Industrial, Lighting,Building, Elevator, Data Center, etc., reducing cost/size/weight
IETF: Standards for IP protocol enhancements for constrained devices
APL: Advanced Physical Layer, Process Automation effort to bring Ethernet
to instruments and other field devices

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