Requirements and Scenarios for Industry Internet Addressing
draft-km-industrial-internet-requirements-00

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Authors Kiran Makhijani  , Lijun Dong 
Last updated 2021-06-10
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Independent Submission                                      K. Makhijani
Internet-Draft                                                   L. Dong
Intended status: Informational                                 Futurewei
Expires: December 12, 2021                                 June 10, 2021

      Requirements and Scenarios for Industry Internet Addressing
              draft-km-industrial-internet-requirements-00

Abstract

   Industry Control Networks host a diverse set of non-internet
   protocols for different purposes.  Even though they operate in a
   controlled environment, one end of industrial control applications
   run over internet technologies (IT) and another over operational
   technology (OT) protocols.  This memo discusses the challenges and
   requirements relating to converegence of OT and IT networks.  One
   particular problem in convergence is figuring out reachability
   between the these networks.

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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Acronymns . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Industrial Network Reference Architecture . . . . . . . . . .   4
     3.1.  Communication Patterns  . . . . . . . . . . . . . . . . .   5
     3.2.  Industry Control Network Nuances (current state)  . . . .   5
   4.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Heterogenity  . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Automation Impact . . . . . . . . . . . . . . . . . . . .   7
       4.2.1.  Scale . . . . . . . . . . . . . . . . . . . . . . . .   8
       4.2.2.  Stretch Control Fabric to Edge and Cloud  . . . . . .   8
       4.2.3.  Reliability . . . . . . . . . . . . . . . . . . . . .   8
       4.2.4.  Resilience  . . . . . . . . . . . . . . . . . . . . .   8
     4.3.  OT/IT Convergence . . . . . . . . . . . . . . . . . . . .   8
     4.4.  Data oriented networking  . . . . . . . . . . . . . . . .   9
     4.5.  Virtualization  . . . . . . . . . . . . . . . . . . . . .   9
   5.  Address Space Requirements  . . . . . . . . . . . . . . . . .   9
     5.1.  Short Device Addressing . . . . . . . . . . . . . . . . .   9
     5.2.  Meaningful Addresses  . . . . . . . . . . . . . . . . . .  10
     5.3.  Device name based  Addresses  . . . . . . . . . . . . . .  10
     5.4.  Adoption of Lean Network Layer  . . . . . . . . . . . . .  10
     5.5.  Multi-semantic behavior . . . . . . . . . . . . . . . . .  10
     5.6.  Interoperability with IP-world machines . . . . . . . . .  11
   6.  Relationship with  Activities in IETF . . . . . . . . . . . .  11
     6.1.  Deterministic Networks (DetNet WG)  . . . . . . . . . . .  11
     6.2.  IoT OPS . . . . . . . . . . . . . . . . . . . . . . . . .  11
     6.3.  LPWAN . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     6.4.  Recent Addressing related work  . . . . . . . . . . . . .  12
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   10. Informative References  . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   An industry control network interconnects devices used to operate,
   control and monitor physical equipment in industrial environments.
   These networks are increasingly becoming complex as the emphasis on
   convergence of OT/IT grows to improve the automation.  On one side of
   Industrial internet are the inventory management, supply chain and
   simulation software and the other side are the control devices

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   operating on machines.  Operational Technologies (OT) networks are
   more often tied to set of non-internet protocols such as Modbus,
   Profibus, CANbus, Profinet, etc.  There are more than 100 different
   protocols each with it's own packet format and are used in the
   industry.

   It is expected that integration between the IT and OT will provide
   numerous benefits in terms of improved productivity, efficiency of
   operations by providing end to end visibility and control.  Industry
   control applications also expect to operate at cloud scale by
   virtualization of several modules (especially PLCs) leading to new
   set of network requirements.

   One aspect of industry control is the delivery of data associated
   with the Real-time, deterministic and reliability characteristics
   over local-area and wide-area networks.  This type of inter-
   operability functionality and study is already covered in DETNET
   working group.  The other aspect is rachability and interconnection
   keeping heterogenity of communication interfaces and a variety of
   services in mind.  This doument focuses on the latter part only.

   OT networks have been traditionally separate from the IT networks.
   It allowed OT network experts to manage and control proceses without
   much dependency on changes in the external networks.  This is an
   important to consideration when dealing with the industry control
   networks to maintain them in a controlled environment leveraging the
   limited-domain networks [LDN] concept for an independent network
   control.

   The purpose of this document is to discuss the reachability and
   interconnection characteristics, challenges and new requirements
   emerging from large-scale integration of IT and OT.

2.  Terminology

   o  Industrial Control Networks: The indutrial control networks are
      interconnection of equipments used for the operation, control or
      monitoring of machines in the industry environment.  It involves
      different level of communications - between fieldbus devices,
      digital controllers and software applications

   o  Industry Automation: Mechansims that enable machine to machine
      communication by use of technologies that enable automatic control
      and operation of industrial devices and processes leading to
      minimizing human intervention.

   o  Human Machine Interface: An interface between the operator and the
      machine.  The communication interface relays I/O data back and

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      forth between an oeprator's terminal anf HMI software to control
      and monitor equipment.

2.1.  Acronymns

   o  HMI: Human Machine Interface

3.  Industrial Network Reference Architecture

   In the scope of this document the following reference industrial
   network will be used to provide structure to the discussion.  In the
   Fig. Figure 1 below, a hierarchy of communications is shown.  At the
   lowest level, PLCs operate and control field devices; above that
   Human Machine Interface (HMI) interconnects with different PLCs to
   program and control underlying field devices.  HMI itself, sends data
   up to applications for consumption in that industry vertical.

        +-+-+-+-+-+-+
     ^  | Data Apps |....             External business logic network
     :  +-+-+-+-+-+-+   :
     :        |         :
     v  +-+-+-+-+-+-+  +-+-+-+-+--+
        | vendor A  |  |vendor B  |     Interconnection of
        | controller|  |controller|     controllers (system integrators)
     ^  +-+-+-+-+-+-+  +-+-+-+-+-+
     :       |         |
     :   +-+-+-+-+  +-+-++-+
     :   | Net X |  | Net Y|
     v   | PLCs  |  | PLCs |--+        device-controllers
     ^   +-+-+-+-+  +-+-+--+  |
     :      |        |        |
     :   +-+-+    +-+-+    +-+-+
     v   |   |    |   |    |   |   Field level devices
         +-+-+    +-+-+    +-+-+

       Figure 1: Hierarchy of Functions Industrial Control Networks

   Unlike commercial networks that uniformly run IP protocols, the
   communication links run different protocols at along the different
   level of the hierarchy.  One of the key requirement from new
   industrial applications is the integration of different types of
   communication protocols including Modbus, Profinet, Profibus,
   ControlNet, CANOpen etc.

   A vertically integration system involves a network between the
   external business applications and higher controllers (for e.g.
   SCADA, HMI, or system integrators) is IP based.  The second level of
   networks between the controllers can be either IP or non-IP

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   (Profibus, BACNet, etc.).  The lowest field-level networks between
   industrial controllers and field-level may be any of the fieldbus or
   device control protocols (More details of the industry networks can
   be found in [SURV]).

3.1.  Communication Patterns

   The following communication patterns are commonly observed:

   o  controller to controller: A communication between multi-vendor
      controller maybe required by system integrators to work in complex
      systems.

   o  controller to field level devices: This is a fieldbus
      communication between device such as I/O modules, motors,
      controllers.  This communication represent.

   o  Device to device: allows direct communication between wired
      industrial devices and wireless devices to enhance automation use
      cases.  For an exmaple, use of camera to visually monitor and
      detect anamolies in other devices.

   o  controller to compute: vertical communication between a controller
      and compute integrates IP-based technologies with non-IP since OT
      product systems and solutions are not connected with IP based
      networks.

   A certain level of inter-operability is required to exchange data
   between the above endpoints from different vendors.  One of the
   challange is that Ethernet (which unifies IT standards) that's not
   always possible in Industry networks.

3.2.  Industry Control Network Nuances (current state)

   The Industry control networks are engineered for the idustry
   verticals they belong to and depict unique properties as below:

   o  location bound: The Control Device's location or the network they
      are attached to is predetermined and changes rarely.  However, the
      network resources may not get efficiently utilized to avoid
      contention between them.

   o  security by separation: Typically, security is enhanced by keeping
      IT/OTnetworks separate.  The operators control how data goes in
      and out of a site through firewalls and policies.

   o  data growth: Even though the size of network remains the same,
      data generated is much higher.  For example, cameras installed for

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      visual inspection to determine the quality of manufactured product
      generates a high bandwidth demand.

   o  Wired device constraints: A bulk of machines are over wired
      network, their constraints vary from LPWAN and IoT devices which
      is an active area of standardization work. device lifetime, or
      power-requirements are not typical constraints.  Instead direct
      process control mechanisms are more important.

   o  Real-time behavior: The control devices require realtime as well
      as deterministic behavior between a controller (such as an HMI
      station) to the equipment.  The DetNet working group covers
      several aspects.

   The goal of the document is not to reinvent the Industry control
   infrastructure.  See section Section 6 on related standards work.  It
   is meant to exclude the already covered by other WGs.

   Since a device connects to network through its address, the document
   explores different address specific nuances in control devies - such
   as management, device discovery and integration requirements.  This
   document concerns with the identification of and role networks,
   specifically from the organization of industry control devices.

   The goal of this document is to outline some of the challenges and
   improvement of connectivity aspects of Industry control networks.

4.  Problem Statement

   In industrial networks, a good number of devices still communicate
   over a serial or field bus (although Ethernet is being gradually
   adopted).  The operations on these devices are performed by writing
   provide direct access to operation-control. i.e what operation to
   perform is embedded in the type of interface itself.  For instance,
   Profibus, Modbus networks are implicitly latency sensitive and short
   control-command based.

     ModBus
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | address | Function  code  | data|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     CANBus

      +-+-+-+-+-+-+-+-+-+-+--+-+-+
      |   message id  |    data  |
      +-+-+-+-+-+-+-+-+-+-+-++-+-+
      Profibus - todo.

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   Since they are localized in an area such as factory floor or a site,
   such networks have evolved independently and are seperated from the
   IT applications.  The emerging trend requires a seamless integration
   with intelligent software, sophisticated compute platforms and other
   operational aspects as highlighted below:

4.1.  Heterogenity

   A typical industry control network has devices of different
   communication interfaces such as Fieldbus (PROFIBUS, Modbus, and
   HART), Ethernet (generic Ethernet/IP, PROFINET, and Modbus-TCP), and
   also wireless (Bluetooth, Wireless HART, and IoT).  These interfaces
   vary at the physical and link layers and because they integrate with
   their own application technologies providing interoperability between
   these devices remains a challenge.  This also makes difficult to
   adopt to modern integration technologies.

   Fieldbus client-server architecture is widely deployed.  It delivers
   commands deterministically from a controller to the device and vice-
   a-versa.  Interfaces of this kind have typically shorter addresses
   (upto 256 devices on a single bus in Modbus).

   Some of the servers also behave as protocol gateways and interconnect
   different type of protocols.  For example when a modbus device is
   being controlled by a profinet server, an gateway function will
   translate modbus data or encapsulate it over IP (if the controller
   supports it).

   In a Gateway-centric approach, gateways are in charge of protocol
   translations between the devices with different interfaces.  This
   requires packing and unpacking of data in the source and destination
   formats at the attached gateways.  Note: As an example, a Modbus
   device does not know whether to send command to Profibus PLC or
   Modbus PLC.  The gateway device attaches to performs the translation.
   This is even worse with encapsulations, where the entire frame is
   carried over IP.

   This is not ideal for latency sensitive applications.  Although
   hardware wise, gateways need to be equipped with all the interface,
   it is more efficient to only perform data link conversion.

4.2.  Automation Impact

   Automation of processes in industry relies on control sophisticated
   technologies such as machine learning, big data, etc. with minimal
   human intervention.  Automation needs to support scale, reliability
   and resiliance at large-scale.

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4.2.1.  Scale

   Automation control at small scale applications with well defined task
   has been possible.  In order to improve production, and eliminate
   stoppages and minimizing human intervention.

   When the number or density of devices, and processes increase there
   is a need to schedule, route, and coordinate over multiple control
   environments.

4.2.2.  Stretch Control Fabric to Edge and Cloud

   The industry control networks can be extended to cloud or edge
   compute platforms.  Since these networks are not equipped with
   compute intensive servers.  Now extending the communication to the
   edge and cloud nodes increases the distance requiring traditional L2
   networks to be adopted to L3 network designs.

   Design decisions will require to choose different transit strategies
   (this maybe layer 1, 2, 3 technologies or even network slices).  It
   also influence the security policies.

4.2.3.  Reliability

   Production efficiency is inversely related to number of defects in a
   process.  System reliability is determined through measurements of
   its instantaneous state.

   Automation processes need to ensure that system is performing in an
   expected state and is capable of reporting anamolies fast and
   accurately (i.e. packet drops or jitter leading to poor quality
   product).

4.2.4.  Resilience

   TBD.

4.3.  OT/IT Convergence

   Most of the factory floors are not equipped with IT servers to
   perform compute intensive tasks.  Yet an IP-based device need to
   connect with non-IP interface to control those devices.

   Often real-time response is necessary for example, in closed-loop
   control systems direct communication is desired to avoid any
   additional packet processing delay or overheades at the source and
   destination gateways, equipping IP to all OT devices and abandoning

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   the existing investment and depolyment could result in the following
   obvious problems.

   o  Many of the standard IP based protocols maybe too much overhead
      for OT devices.

   o  Cannot preserve communication characteristics of devices
      (different device addressing scheme, realtime, IRT, message
      identifiers, Bus-like properties).

   o  It relies heavily on hierarchy network stack (network layer,
      transport layer, application), where as OT devices do not have
      any, they generally operate at data link layer or below.

4.4.  Data oriented networking

   Industry verticals keep data and control on the manufacturing floor,
   on a closed system.  There is no easy way to forward this data to
   enterprise level software.  On premise micro data centers or edge
   computing are new infrastructure pieces that wil impact the design of
   current industrial networks.

4.5.  Virtualization

   Traditional Industry control infrastructure is not virtualized.
   Virtualization will enable deployment of new functionality in a
   flexible manner.

   o  Virtual PLCs are considered an important component functionality
      customization of digital-twin realization.

   o  virtualization enables edge and cloud native computing by moving
      and instantiating workflows at different locations.

   Implications that PLCs are no longer one-hop away.

5.  Address Space Requirements

5.1.  Short Device Addressing

   Shorter addresses are inherent to industry control systems to provide
   implicit determinism.

   Note: The motivation for short address is to preseve the legacy
   attributes of fieldbus control devices.  It is not related low-power
   or resource constraints.

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   A large volume of the messages are of sizes shorter than the size of
   IP headers (v4, v6) themselves.  The header tax will be very high
   over industry control networks.

5.2.  Meaningful Addresses

   The industry control floors are built bottom-up.  The devices are
   carefully wired and connected to controllers.  In a hierarchical
   network design, a particular type of machine can be reached in a
   structured manner by adding subnet or location to the address
   structures.

5.3.  Device name based Addresses

   HMI might require human readable address that is undertandable to
   human operators or application end users.  For example, a device
   address could be associated with its location, type of applications,
   attached objects etc.  The network needs to support the resolution
   and routing based on such device addresses, which is more user
   friendly.  On the other hand, grouping devices based on their
   addresses shall be easily implemented to enable group operation and
   communication.

5.4.  Adoption of Lean Network Layer

   Challenge of Industrial network device address is that it
   communicates to a physical device address.  Traditionally, in a
   limited environment there was no need for network layer or expressing
   network specific service, access control.

   o  If a sensor is broken, it will require reprogramming of controller
      and re-aligning with the new address.  The benefit of network
      layer, removes this restriction.

   o  Note that, using IP stack is not suitable because these devices
      perform specific functions and any overhead in transport or large
      addressing can add to processing delays.

   o  Several other IP suite protocols such as device discovery should
      be revisited.

5.5.  Multi-semantic behavior

   OT networks, at least at site level are organized at much smaller
   scale than typical IP-capable networks.  There is in turn a fixed
   hierarchy of networks w.r.t. location in a plant.

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5.6.  Interoperability with IP-world machines

   To develop further on different type of address format support.  From
   smaller address of legacy devices to IT based applications with IP
   address.

   (OT-Address )--->(Industry Control)--->(IP-Address)
   (control dev)    (   network      )    (application)

   Preferably allow OT devices to understand IP-addresses for the
   servers they connect to.

6.  Relationship with Activities in IETF

6.1.  Deterministic Networks (DetNet WG)

   The Deterministic Networking (DetNet) [DETNET-ARCH] is working on
   using IP for long-range connectivity with bounded latency in industry
   control networks . Its data plane [DETNET-DP] takes care of
   forwarding aspects and most close to Industry control networks but
   the focus is on the controlled latency, low packet loss & delay
   variation, and high reliability functions.  Not dealing with
   interconnection of devices.

   In layer 2 domain, similar functionalty is convered by TSN Ethernet
   [IEEE802.1TSNTG].

6.2.  IoT OPS

   IoT operations group discusses device security, privacy, and
   bootstrapping and device onboarding concepts.  Among the device
   provisioning one of the object is network identifier.  We understand
   that the IoT OPs does not exclude evaluation of industry IoT or
   control devices requirements.  Given the specific functions described
   above it maybe necessary to configure more than an identifier, i.e.
   server or controller information or specific address scope and
   structure.

6.3.  LPWAN

   The LPWAN has focussed on low-power and constrained devices.  There
   are compression related approaches that may apply are [SCHC] or
   [ROHC].  To be evaluated for process control devices.

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6.4.  Recent Addressing related work

   Some of the work initiated on the addressing include solutions such
   as [FlexIP], [Flexible_IP], [FHE], and [SOIP].

   Recently, a broader area of problem statement and challenges in
   [CHALLEN].

7.  IANA Considerations

   This document requires no actions from IANA.

8.  Security Considerations

   This document introduces no new security issues.

9.  Acknowledgements

10.  Informative References

   [CHALLEN]  Jia, Y., Trossen, D., Iannone, L., 3rd, D. E. E., and P.
              Liu, "Challenging Scenarios and Problems in Internet
              Addressing", draft-jia-intarea-scenarios-problems-
              addressing-00 (work in progress), February 2021.

   [DETNET-ARCH]
              Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", RFC 8655,
              DOI 10.17487/RFC8655, October 2019,
              <https://www.rfc-editor.org/info/rfc8655>.

   [DETNET-DP]
              Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S.
              Bryant, "Deterministic Networking (DetNet) Data Plane:
              IP", RFC 8939, DOI 10.17487/RFC8939, November 2020,
              <https://www.rfc-editor.org/info/rfc8939>.

   [FHE]      Jiang, S., Li, G., and B. Carpenter, "Asymmetric IPv6 for
              Resource-constrained IoT Networks", draft-jiang-
              asymmetric-ipv6-04 (work in progress), November 2020.

   [Flexible_IP]
              Jia, Y., Chen, Z., and S. Jiang, "Flexible IP: An
              Adaptable IP Address Structure", draft-jia-flex-ip-
              address-structure-00 (work in progress), October 2020.

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   [FlexIP]   Moskowitz, R., Li, G., and S. Ren, "FlexIP Addressing",
              draft-moskowitz-flexip-addressing-00 (work in progress),
              January 2019.

   [IEEE802.1TSNTG]
              "IEEE, "Time-Sensitive Networking (TSN) Task Group"",
              2018, <https://1.ieee802.org/tsn>.

   [LDN]      Carpenter, B. and B. Liu, "Limited Domains and Internet
              Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020,
              <https://www.rfc-editor.org/info/rfc8799>.

   [ROHC]     Jonsson, L-E., Pelletier, G., and K. Sandlund, "The RObust
              Header Compression (ROHC) Framework", RFC 4995,
              DOI 10.17487/RFC4995, July 2007,
              <https://www.rfc-editor.org/info/rfc4995>.

   [SCHC]     Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC.
              Zuniga, "SCHC: Generic Framework for Static Context Header
              Compression and Fragmentation", RFC 8724,
              DOI 10.17487/RFC8724, April 2020,
              <https://www.rfc-editor.org/info/rfc8724>.

   [SOIP]     Carpenter, B., Jiang, S., and G. Li, "Service Oriented
              Internet Protocol", draft-jiang-service-oriented-ip-03
              (work in progress), May 2020.

   [SURV]     Galloway, B. and G. Hancke, "Introduction to Industrial
              Control Networks", IEEE Communications Surveys &
              Tutorials Vol. 15, pp. 860-880,
              DOI 10.1109/surv.2012.071812.00124, 2013.

Authors' Addresses

   Kiran Makhijani
   Futurewei

   Email: kiran.ietf@gmail.com

   Lijun Dong
   Futurewei
   Central Expy
   Santa Clara, CA 95050
   United States of America

   Email: lijun.dong@futurewei.com

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