Requirements and Scenarios for Industry Internet AddressingFutureweikiran.ietf@gmail.comFutureweiCentral ExpySanta Clara, CA 95050United States of Americalijun.dong@futurewei.com
INTAREA
Independent SubmissionInternet-DraftIndustry 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.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 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 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.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 applicationsIndustry 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.Human Machine Interface: An interface between the operator and the machine. The communication interface relays I/O data back and forth between an oeprator’s terminal anf HMI software to control and monitor equipment.HMI: Human Machine InterfaceIn the scope of this document the following reference industrial network will be used to provide structure to the discussion. In the Fig. 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.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 (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 ).The following communication patterns are commonly observed:controller to controller: A communication between multi-vendor controller maybe required by system integrators to work in complex systems.controller to field level devices: This is a fieldbus communication between device such as I/O modules, motors, controllers. This communication represent.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.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.The Industry control networks are engineered for the idustry verticals they belong to and depict unique properties as below: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.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.data growth: Even though the size of network remains the same, data generated is much higher. For example, cameras installed for visual inspection to determine the quality of manufactured product generates a high bandwidth demand.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.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 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.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.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: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.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.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.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.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).TBD.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 the existing investment and depolyment could result in the following obvious problems.Many of the standard IP based protocols maybe too much overhead for OT devices.Cannot preserve communication characteristics of devices (different device addressing scheme, realtime, IRT, message identifiers, Bus-like properties).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.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.Traditional Industry control infrastructure is not virtualized. Virtualization will enable deployment of new functionality in a flexible manner.Virtual PLCs are considered an important component functionality customization of digital-twin realization.virtualization enables edge and cloud native computing by moving and instantiating workflows at different locations.Implications that PLCs are no longer one-hop away.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.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.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.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.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.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.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.Several other IP suite protocols such as device discovery should be revisited.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.To develop further on different type of address format support. From smaller address of legacy devices to IT based applications with IP address.Preferably allow OT devices to understand IP-addresses for the servers they connect to.The Deterministic Networking (DetNet) is working on using IP for long-range connectivity with bounded latency in industry control networks . Its data plane 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 .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.The LPWAN has focussed on low-power and constrained devices. There are compression related approaches that may apply are or .
To be evaluated for process control devices.Some of the work initiated on the addressing include solutions
such as , , , and .Recently, a broader area of problem statement and challenges in .This document requires no actions from IANA.This document introduces no new security issues.Limited Domains and Internet ProtocolsThere is a noticeable trend towards network behaviors and semantics that are specific to a particular set of requirements applied within a limited region of the Internet. Policies, default parameters, the options supported, the style of network management, and security requirements may vary between such limited regions. This document reviews examples of such limited domains (also known as controlled environments), notes emerging solutions, and includes a related taxonomy. It then briefly discusses the standardization of protocols for limited domains. Finally, it shows the need for a precise definition of "limited domain membership" and for mechanisms to allow nodes to join a domain securely and to find other members, including boundary nodes. This document is the product of the research of the authors. It has been produced through discussions and consultation within the IETF but is not the product of IETF consensus.Deterministic Networking (DetNet) Data Plane: IPThis document specifies the Deterministic Networking (DetNet) data plane operation for IP hosts and routers that provide DetNet service to IP-encapsulated data. No DetNet-specific encapsulation is defined to support IP flows; instead, the existing IP-layer and higher-layer protocol header information is used to support flow identification and DetNet service delivery. This document builds on the DetNet architecture (RFC 8655) and data plane framework (RFC 8938).Deterministic Networking ArchitectureThis document provides the overall architecture for Deterministic Networking (DetNet), which provides a capability to carry specified unicast or multicast data flows for real-time applications with extremely low data loss rates and bounded latency within a network domain. Techniques used include 1) reserving data-plane resources for individual (or aggregated) DetNet flows in some or all of the intermediate nodes along the path of the flow, 2) providing explicit routes for DetNet flows that do not immediately change with the network topology, and 3) distributing data from DetNet flow packets over time and/or space to ensure delivery of each packet's data in spite of the loss of a path. DetNet operates at the IP layer and delivers service over lower-layer technologies such as MPLS and Time- Sensitive Networking (TSN) as defined by IEEE 802.1.SCHC: Generic Framework for Static Context Header Compression and FragmentationThis document defines the Static Context Header Compression and fragmentation (SCHC) framework, which provides both a header compression mechanism and an optional fragmentation mechanism. SCHC has been designed with Low-Power Wide Area Networks (LPWANs) in mind.SCHC compression is based on a common static context stored both in the LPWAN device and in the network infrastructure side. This document defines a generic header compression mechanism and its application to compress IPv6/UDP headers.This document also specifies an optional fragmentation and reassembly mechanism. It can be used to support the IPv6 MTU requirement over the LPWAN technologies. Fragmentation is needed for IPv6 datagrams that, after SCHC compression or when such compression was not possible, still exceed the Layer 2 maximum payload size.The SCHC header compression and fragmentation mechanisms are independent of the specific LPWAN technology over which they are used. This document defines generic functionalities and offers flexibility with regard to parameter settings and mechanism choices. This document standardizes the exchange over the LPWAN between two SCHC entities. Settings and choices specific to a technology or a product are expected to be grouped into profiles, which are specified in other documents. Data models for the context and profiles are out of scope.The RObust Header Compression (ROHC) FrameworkThe Robust Header Compression (ROHC) protocol provides an efficient, flexible, and future-proof header compression concept. It is designed to operate efficiently and robustly over various link technologies with different characteristics.The ROHC framework, along with a set of compression profiles, was initially defined in RFC 3095. To improve and simplify the ROHC specifications, this document explicitly defines the ROHC framework and the profile for uncompressed separately. More specifically, the definition of the framework does not modify or update the definition of the framework specified by RFC 3095. [STANDARDS-TRACK]FlexIP AddressingHTT ConsultingHuaweiHuawei This memo proposes an unbounded Flexible Address Space (FAS),
consisting of a publicly routable Global Address Part (GP) and a
locally routable Local Address Part (LP). It expands GP and LP to
provide address privacy and special LP formats. Use cases are also
provided.
Flexible IP: An Adaptable IP Address StructureHuawei Technologies Co., LtdHuawei Technologies Co., LtdHuawei Technologies Co., Ltd Along as the popularization and adoption of IP in emerging scenarios,
challenges emerge as well due to the ossified address structure. To
enable TCP/IP in networks that previously using exclusive protocol, a
flexible address structure would be far more preferred for their
particular properties
[draft-jia-scenarios-flexible-address-structure].
This document describes a flexible address structure -- Flexible IP
(FlexIP) acting on limited domains [RFC8799]. FlexIP is expected to
proactively adapt scenarios under flexible address structure.
Meanwhile, FlexIP still benefit from global reachability based on the
IPv6 interoperability.
Challenging Scenarios and Problems in Internet AddressingHuawei Technologies Co., LtdHuawei Technologies Duesseldorf GmbHHuawei Technologies France S.A.S.U.Futurewei TechnologiesChina Mobile The Internet Protocol (IP) has been the major technological success
in information technology of the last half century. As Internet
become pervasive, IP start replacing communication technology for
domain-specific solutions. However, domains with specific
requirements as well as communication behaviors and semantics still
exists and represent what [RFC8799] recognizes as "limited domains".
When communicating within limited domains, the address semantic and
format may differ with respect to the IP address one. As such, there
is a need to adapt the domain-specific addressing to the Internet
addressing paradigm. In certain scenarios, such adaptation may raise
challenges.
This document describes well-recognized scenarios that showcase
possibly different addressing requirements which are challenging to
be accommodated in the IP addressing model. These scenarios
highlight issues related to the Internet addressing model and call
for starting a discussion on a way to re-think/evolve the addressing
model so to better accommodate different domain-specific
requirements.
Service Oriented Internet ProtocolThe University of AucklandHuawei Technologies Co., LtdHuawei Technologies This document proposes a new, backwards-compatible, approach to
packet forwarding, where the service required rather than the IP
address required acts as the vector for routing packets at the edge
of the network. Deeper in the network, the mechanism can interface
to conventional and future methods of service or application aware
networking.
Asymmetric IPv6 for Resource-constrained IoT NetworksHuawei Technologies Co., LtdHuawei TechnologiesThe University of Auckland This document describes a new approach to IPv6 header compression for
use in scenarios where minimizing packet size is crucial but routing
performance must be maximised.
IEEE, "Time-Sensitive Networking (TSN) Task Group"Introduction to Industrial Control Networks