Internet Engineering Task Force M. Ersue, Ed.
Internet-Draft Nokia Networks
Intended status: Informational D. Romascanu
Expires: January 5, 2015 Avaya
J. Schoenwaelder
A. Sehgal
Jacobs University Bremen
July 4, 2014
Management of Networks with Constrained Devices: Use Cases
draft-ietf-opsawg-coman-use-cases-02
Abstract
This document discusses use cases concerning the management of
networks, where constrained devices are involved. A problem
statement, deployment options and the requirements on the networks
with constrained devices can be found in the companion document on
"Management of Networks with Constrained Devices: Problem Statement
and Requirements".
Status of This Memo
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This Internet-Draft will expire on January 5, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Access Technologies . . . . . . . . . . . . . . . . . . . . . 4
2.1. Constrained Access Technologies . . . . . . . . . . . . . 4
2.2. Cellular Access Technologies . . . . . . . . . . . . . . 4
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Environmental Monitoring . . . . . . . . . . . . . . . . 6
3.2. Infrastructure Monitoring . . . . . . . . . . . . . . . . 6
3.3. Industrial Applications . . . . . . . . . . . . . . . . . 7
3.4. Energy Management . . . . . . . . . . . . . . . . . . . . 9
3.5. Medical Applications . . . . . . . . . . . . . . . . . . 11
3.6. Building Automation . . . . . . . . . . . . . . . . . . . 12
3.7. Home Automation . . . . . . . . . . . . . . . . . . . . . 13
3.8. Transport Applications . . . . . . . . . . . . . . . . . 14
3.9. Community Network Applications . . . . . . . . . . . . . 16
3.10. Field Operations . . . . . . . . . . . . . . . . . . . . 18
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
5. Security Considerations . . . . . . . . . . . . . . . . . . . 19
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
8. Informative References . . . . . . . . . . . . . . . . . . . 20
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 21
A.1. draft-ietf-opsawg-coman-use-cases-01 - draft-ietf-opsawg-
coman-use-cases-02 . . . . . . . . . . . . . . . . . . . 21
A.2. draft-ietf-opsawg-coman-use-cases-00 - draft-ietf-opsawg-
coman-use-cases-01 . . . . . . . . . . . . . . . . . . . 22
A.3. draft-ersue-constrained-mgmt-03 - draft-ersue-opsawg-
coman-use-cases-00 . . . . . . . . . . . . . . . . . . . 23
A.4. draft-ersue-constrained-mgmt-02-03 . . . . . . . . . . . 23
A.5. draft-ersue-constrained-mgmt-01-02 . . . . . . . . . . . 24
A.6. draft-ersue-constrained-mgmt-00-01 . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction
Small devices with limited CPU, memory, and power resources, so
called constrained devices (aka. sensor, smart object, or smart
device) can be connected to a network. Such a network of constrained
devices itself may be constrained or challenged, e.g., with
unreliable or lossy channels, wireless technologies with limited
bandwidth and a dynamic topology, needing the service of a gateway or
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proxy to connect to the Internet. In other scenarios, the
constrained devices can be connected to a non-constrained network
using off-the-shelf protocol stacks. Constrained devices might be in
charge of gathering information in diverse settings including natural
ecosystems, buildings, and factories and send the information to one
or more server stations.
Network management is characterized by monitoring network status,
detecting faults, and inferring their causes, setting network
parameters, and carrying out actions to remove faults, maintain
normal operation, and improve network efficiency and application
performance. The traditional network management application
periodically collects information from a set of elements that are
needed to manage, processes the data, and presents them to the
network management users. Constrained devices, however, often have
limited power, low transmission range, and might be unreliable. They
might also need to work in hostile environments with advanced
security requirements or need to be used in harsh environments for a
long time without supervision. Due to such constraints, the
management of a network with constrained devices offers different
type of challenges compared to the management of a traditional IP
network.
This document aims to understand use cases for the management of a
network, where constrained devices are involved. The document lists
and discusses diverse use cases for the management from the network
as well as from the application point of view. The list of discussed
use cases is not an exhaustive one since other scenarios, currently
unknown to the authors, are possible. are The application scenarios
discussed aim to show where networks of constrained devices are
expected to be deployed. For each application scenario, we first
briefly describe the characteristics followed by a discussion on how
network management can be provided, who is likely going to be
responsible for it, and on which time-scale management operations are
likely to be carried out.
A problem statement, deployment and management topology options as
well as the requirements on the networks with constrained devices can
be found in the companion document [COM-REQ].
This documents builds on the terminology defined in [RFC7228] and
[COM-REQ]. [RFC7228] is a base document for the terminology
concerning constrained devices and constrained networks. Some use
cases specific to IPv6 over Low-Power Wireless Personal Area Networks
(6LoWPANs) can be found in [RFC6568].
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2. Access Technologies
Besides the management requirements imposed by the different use
cases, the access technologies used by constrained devices can impose
restrictions and requirements upon the Network Management System
(NMS) and protocol of choice.
It is possible that some networks of constrained devices might
utilize traditional non-constrained access technologies for network
access, e.g., local area networks with plenty of capacity. In such
scenarios, the constrainedness of the device presents special
management restrictions and requirements rather than the access
technology utilized.
However, in other situations constrained or cellular access
technologies might be used for network access, thereby causing
management restrictions and requirements to arise as a result of the
underlying access technologies.
2.1. Constrained Access Technologies
Due to resource restrictions, embedded devices deployed as sensors
and actuators in the various use cases utilize low-power low data-
rate wireless access technologies such as IEEE 802.15.4, DECT ULE or
BT-LE for network connectivity.
In such scenarios, it is important for the NMS to be aware of the
restrictions imposed by these access technologies to efficiently
manage these constrained devices. Specifically, such low-power low
data-rate access technologies typically have small frame sizes. So
it would be important for the NMS and management protocol of choice
to craft packets in a way that avoids fragmentation and reassembly of
packets since this can use valuable memory on constrained devices.
Devices using such access technologies might operate via a gateway
that translates between these access technologies and more
traditional Internet protocols. A hierarchical approach to device
management in such a situation might be useful, wherein the gateway
device is in-charge of devices connected to it, while the NMS
conducts management operations only to the gateway.
2.2. Cellular Access Technologies
Machine to machine (M2M) services are increasingly provided by mobile
service providers as numerous devices, home appliances, utility
meters, cars, video surveillance cameras, and health monitors, are
connected with mobile broadband technologies. Different
applications, e.g., in a home appliance or in-car network, use
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Bluetooth, Wi-Fi or Zigbee locally and connect to a cellular module
acting as a gateway between the constrained environment and the
mobile cellular network.
Such a gateway might provide different options for the connectivity
of mobile networks and constrained devices:
o a smart phone with 3G/4G and WLAN radio might use BT-LE to connect
to the devices in a home area network,
o a femtocell might be combined with home gateway functionality
acting as a low-power cellular base station connecting smart
devices to the application server of a mobile service provider,
o an embedded cellular module with LTE radio connecting the devices
in the car network with the server running the telematics service,
o an M2M gateway connected to the mobile operator network supporting
diverse IoT connectivity technologies including ZigBee and CoAP
over 6LoWPAN over IEEE 802.15.4.
Common to all scenarios above is that they are embedded in a service
and connected to a network provided by a mobile service provider.
Usually there is a hierarchical deployment and management topology in
place where different parts of the network are managed by different
management entities and the count of devices to manage is high (e.g.
many thousands). In general, the network is comprised by manifold
type and size of devices matching to different device classes. As
such, the managing entity needs to be prepared to manage devices with
diverse capabilities using different communication or management
protocols. In case the devices are directly connected to a gateway
they most likely are managed by a management entity integrated with
the gateway, which itself is part of the Network Management System
(NMS) run by the mobile operator. Smart phones or embedded modules
connected to a gateway might be themselves in charge to manage the
devices on their level. The initial and subsequent configuration of
such a device is mainly based on self-configuration and is triggered
by the device itself.
The gateway might be in charge of filtering and aggregating the data
received from the device as the information sent by the device might
be mostly redundant.
3. Use Cases
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3.1. Environmental Monitoring
Environmental monitoring applications are characterized by the
deployment of a number of sensors to monitor emissions, water
quality, or even the movements and habits of wildlife. Other
applications in this category include earthquake or tsunami early-
warning systems. The sensors often span a large geographic area,
they can be mobile, and they are often difficult to replace.
Furthermore, the sensors are usually not protected against tampering.
Management of environmental monitoring applications is largely
concerned with the monitoring whether the system is still functional
and the roll-out of new constrained devices in case the system looses
too much of its structure. The constrained devices themselves need
to be able to establish connectivity (auto-configuration) and they
need to be able to deal with events such as loosing neighbors or
being moved to other locations.
Management responsibility typically rests with the organization
running the environmental monitoring application. Since these
monitoring applications must be designed to tolerate a number of
failures, the time scale for detecting and recording failures is for
some of these applications likely measured in hours and repairs might
easily take days. In fact, in some scenarios it might be more cost-
and time-effective to not repair such devices at all. However, for
certain environmental monitoring applications, much tighter time
scales may exist and might be enforced by regulations (e.g.,
monitoring of nuclear radiation).
3.2. Infrastructure Monitoring
Infrastructure monitoring is concerned with the monitoring of
infrastructures such as bridges, railway tracks, or (offshore)
windmills. The primary goal is usually to detect any events or
changes of the structural conditions that can impact the risk and
safety of the infrastructure being monitored. Another secondary goal
is to schedule repair and maintenance activities in a cost effective
manner.
The infrastructure to monitor might be in a factory or spread over a
wider area but difficult to access. As such, the network in use
might be based on a combination of fixed and wireless technologies,
which use robust networking equipment and support reliable
communication via application layer transactions. It is likely that
constrained devices in such a network are mainly C2 devices and have
to be controlled centrally by an application running on a server. In
case such a distributed network is widely spread, the wireless
devices might use diverse long-distance wireless technologies such as
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WiMAX, or 3G/LTE, e.g. based on embedded hardware modules. In cases,
where an in-building network is involved, the network can be based on
Ethernet or wireless technologies suitable for in-building usage.
The management of infrastructure monitoring applications is primarily
concerned with the monitoring of the functioning of the system.
Infrastructure monitoring devices are typically rolled out and
installed by dedicated experts and changes are rare since the
infrastructure itself changes rarely. However, monitoring devices
are often deployed in unsupervised environments and hence special
attention must be given to protecting the devices from being
modified.
Management responsibility typically rests with the organization
owning the infrastructure or responsible for its operation. The time
scale for detecting and recording failures is likely measured in
hours and repairs might easily take days. However, certain events
(e.g., natural disasters) may require that status information be
obtained much more quickly and that replacements of failed sensors
can be rolled out quickly (or redundant sensors are activated
quickly). In case the devices are difficult to access, a self-
healing feature on the device might become necessary.
3.3. Industrial Applications
Industrial Applications and smart manufacturing refer to tasks such
as networked control and monitoring of manufacturing equipment, asset
and situation management, or manufacturing process control. For the
management of a factory it is becoming essential to implement smart
capabilities. From an engineering standpoint, industrial
applications are intelligent systems enabling rapid manufacturing of
new products, dynamic response to product demands, and real-time
optimization of manufacturing production and supply chain networks.
Potential industrial applications (e.g., for smart factories and
smart manufacturing) are:
o Digital control systems with embedded, automated process controls,
operator tools, as well as service information systems optimizing
plant operations and safety.
o Asset management using predictive maintenance tools, statistical
evaluation, and measurements maximizing plant reliability.
o Smart sensors detecting anomalies to avoid abnormal or
catastrophic events.
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o Smart systems integrated within the industrial energy management
system and externally with the smart grid enabling real-time
energy optimization.
Management of Industrial Applications and smart manufacturing may in
some situations involve Building Automation tasks such as control of
energy, HVAC (heating, ventilation, and air conditioning), lighting,
or access control. Interacting with management systems from other
application areas might be important in some cases (e.g.,
environmental monitoring for electric energy production, energy
management for dynamically scaling manufacturing, vehicular networks
for mobile asset tracking).
Sensor networks are an essential technology used for smart
manufacturing. Measurements, automated controls, plant optimization,
health and safety management, and other functions are provided by a
large number of networked sectors. Data interoperability and
seamless exchange of product, process, and project data are enabled
through interoperable data systems used by collaborating divisions or
business systems. Intelligent automation and learning systems are
vital to smart manufacturing but must be effectively integrated with
the decision environment. Wireless sensor networks (WSN) have been
developed for machinery Condition-based Maintenance (CBM) as they
offer significant cost savings and enable new functionalities.
Inaccessible locations, rotating machinery, hazardous areas, and
mobile assets can be reached with wireless sensors. WSNs can provide
today wireless link reliability, real-time capabilities, and quality-
of-service and enable industrial and related wireless sense and
control applications.
Management of industrial and factory applications is largely focused
on the monitoring whether the system is still functional, real-time
continuous performance monitoring, and optimization as necessary.
The factory network might be part of a campus network or connected to
the Internet. The constrained devices in such a network need to be
able to establish configuration themselves (auto-configuration) and
might need to deal with error conditions as much as possible locally.
Access control has to be provided with multi-level administrative
access and security. Support and diagnostics can be provided through
remote monitoring access centralized outside of the factory.
Management responsibility is typically owned by the organization
running the industrial application. Since the monitoring
applications must handle a potentially large number of failures, the
time scale for detecting and recording failures is for some of these
applications likely measured in minutes. However, for certain
industrial applications, much tighter time scales may exist, e.g. in
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real-time, which might be enforced by the manufacturing process or
the use of critical material.
3.4. Energy Management
The EMAN working group developed an energy management framework
[I-D.ietf-eman-framework] for devices and device components within or
connected to communication networks. This document observes that one
of the challenges of energy management is that a power distribution
network is responsible for the supply of energy to various devices
and components, while a separate communication network is typically
used to monitor and control the power distribution network. Devices
in the context of energy management can be monitored for parameters
like Power, Energy, Demand and Power Quality. If a device contains
batteries, they can be also monitored and managed.
Energy devices differ in complexity and may include basic sensors or
switches, specialized electrical meters, or power distribution units
(PDU), and subsystems inside the network devices (routers, network
switches) or home or industrial appliances. The operators of an
Energy Management System are either the utility providers or
customers that aim to control and reduce the energy consumption and
the associated costs. The topology in use differs and the deployment
can cover areas from small surfaces (individual homes) to large
geographical areas. The EMAN requirements document [RFC6988]
discusses the requirements for energy management concerning
monitoring and control functions.
It is assumed that Energy Management will apply to a large range of
devices of all classes and networks topologies. Specific resource
monitoring like battery utilization and availability may be specific
to devices with lower physical resources (device classes C0 or C1).
Energy Management is especially relevant to the Smart Grid. A Smart
Grid is an electrical grid that uses data networks to gather and to
act on energy and power-related information in an automated fashion
with the goal to improve the efficiency, reliability, economics, and
sustainability of the production and distribution of electricity.
Smart Metering is a good example of Smart Grid based Energy
Management applications. Different types of possibly wireless small
meters produce all together a large amount of data, which is
collected by a central entity and processed by an application server,
which may be located within the customer's residence or off-site in a
data-center. The communication infrastructure can be provided by a
mobile network operator as the meters in urban areas will have most
likely a cellular or WiMAX radio. In case the application server is
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located within the residence, such meters are more likely to use WiFi
protocols to interconnect with an existing network.
An Advanced Metering Infrastructure (AMI) network is another example
of the Smart Grid that enables an electric utility to retrieve
frequent electric usage data from each electric meter installed at a
customer's home or business. Unlike Smart Metering, in which case
the customer or their agents install appliance level meters, an AMI
infrastructure is typically managed by the utility providers and
could also include other distribution automation devices like
transformers and reclosers. Meters in AMI networks typically contain
constrained devices that connect to mesh networks with a low-
bandwidth radio. Usage data and outage notifications can be sent by
these meters to the utility's headend systems, via aggregation points
of higher-end router devices that bridge the constrained network to a
less constrained network via cellular, WiMAX, or Ethernet. Unlike
meters, these higher-end devices might be installed on utility poles
owned and operated by a separate entity.
It thereby becomes important for a management application to not only
be able to work with diverse types of devices, but also over multiple
links that might be operated and managed by separate entities, each
having divergent policies for their own devices and network segments.
During management operations, like firmware updates, it is important
that the management system performs robustly in order to avoid
accidental outages of critical power systems that could be part of
AMI networks. In fact, since AMI networks must also report on
outages, the management system might have to manage the energy
properties of battery operated AMI devices themselves as well.
A management system for home based Smart Metering solutions is likely
to have few devices laid out in a simple topology. However, AMI
networks installations could have thousands of nodes per router,
i.e., higher-end device, which organize themselves in an ad-hoc
manner. As such, a management system for AMI networks will need to
discover and operate over complex topologies as well. In some
situations, it is possible that the management system might also have
to setup and manage the topology of nodes, especially critical
routers. Encryption key management and sharing in both types of
network is also likely to be important for providing confidentiality
for all data traffic. In AMI networks the key may be obtained by a
meter only after an end-to-end authentication process based on
certificates. Smart Metering solution could adopt a similar approach
or the security may be implied due to the encrypted WiFi networks
they become part of.
The management of such a network requires end-to-end management of
and information exchange through different types of networks.
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However, as of today there is no integrated energy management
approach and no common information model available. Specific energy
management applications or network islands use their own management
mechanisms.
3.5. Medical Applications
Constrained devices can be seen as an enabling technology for
advanced and possibly remote health monitoring and emergency
notification systems, ranging from blood pressure and heart rate
monitors to advanced devices capable to monitor implanted
technologies, such as pacemakers or advanced hearing aids. Medical
sensors may not only be attached to human bodies, they might also
exist in the infrastructure used by humans such as bathrooms or
kitchens. Medical applications will also be used to ensure
treatments are being applied properly and they might guide people
losing orientation. Fitness and wellness applications, such as
connected scales or wearable heart monitors, encourage consumers to
exercise and empower self-monitoring of key fitness indicators.
Different applications use Bluetooth, Wi-Fi or Zigbee connections to
access the patient's smartphone or home cellular connection to access
the Internet.
Constrained devices that are part of medical applications are managed
either by the users of those devices or by an organization providing
medical (monitoring) services for physicians. In the first case,
management must be automatic and or easy to install and setup by
average people. In the second case, it can be expected that devices
be controlled by specially trained people. In both cases, however,
it is crucial to protect the privacy of the people to which medical
devices are attached. Even though the data collected by a heart beat
monitor might be protected, the pure fact that someone carries such a
device may need protection. As such, certain medical appliances may
not want to participate in discovery and self-configuration protocols
in order to remain invisible.
Many medical devices are likely to be used (and relied upon) to
provide data to physicians in critical situations since the biggest
market is likely elderly and handicapped people. Timely delivery of
data can be quite important in certain applications like patient
mobility monitoring in oldage homes. Data must reach the physician
and/or emergency services within specified limits of time in order to
be useful. As such, fault detection of the communication network or
the constrained devices becomes a crucial function of the management
system that must be carried out with high reliability and, depending
on the medical appliance and its application, within seconds.
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3.6. Building Automation
Building automation comprises the distributed systems designed and
deployed to monitor and control the mechanical, electrical and
electronic systems inside buildings with various destinations (e.g.,
public and private, industrial, institutions, or residential).
Advanced Building Automation Systems (BAS) may be deployed
concentrating the various functions of safety, environmental control,
occupancy, security. More and more the deployment of the various
functional systems is connected to the same communication
infrastructure (possibly Internet Protocol based), which may involve
wired or wireless communications networks inside the building.
Building automation requires the deployment of a large number
(10-100.000) of sensors that monitor the status of devices, and
parameters inside the building and controllers with different
specialized functionality for areas within the building or the
totality of the building. Inter-node distances between neighboring
nodes vary between 1 to 20 meters. Contrary to home automation, in
building management the devices are expected to be managed assets and
known to a set of commissioning tools and a data storage, such that
every connected device has a known origin. The management includes
verifying the presence of the expected devices and detecting the
presence of unwanted devices.
Examples of functions performed by such controllers are regulating
the quality, humidity, and temperature of the air inside the building
and lighting. Other systems may report the status of the machinery
inside the building like elevators, or inside the rooms like
projectors in meeting rooms. Security cameras and sensors may be
deployed and operated on separate dedicated infrastructures connected
to the common backbone. The deployment area of a BAS is typically
inside one building (or part of it) or several buildings
geographically grouped in a campus. A building network can be
composed of network segments, where a network segment covers a floor,
an area on the floor, or a given functionality (e.g., security
cameras).
Some of the sensors in Building Automation Systems (for example fire
alarms or security systems) register, record and transfer critical
alarm information and therefore must be resilient to events like loss
of power or security attacks. This leads to the need to certify
components and subsystems operating in such constrained conditions
based on specific requirements. Also in some environments, the
malfunctioning of a control system (like temperature control) needs
to be reported in the shortest possible time. Complex control
systems can misbehave, and their critical status reporting and safety
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algorithms need to be basic and robust and perform even in critical
conditions.
Building Automation solutions are deployed in some cases in newly
designed buildings, in other cases it might be over existing
infrastructures. In the first case, there is a broader range of
possible solutions, which can be planned for the infrastructure of
the building. In the second case the solution needs to be deployed
over an existing infrastructure taking into account factors like
existing wiring, distance limitations, the propagation of radio
signals over walls and floors, thereby making deployment difficult.
As a result, some of the existing WLAN solutions (e.g., IEEE 802.11
or IEEE 802.15) may be deployed. In mission-critical or security
sensitive environments and in cases where link failures happen often,
topologies that allow for reconfiguration of the network and
connection continuity may be required. Some of the sensors deployed
in building automation may be very simple constrained devices for
which class 0 or class 1 may be assumed.
For lighting applications, groups of lights must be defined and
managed. Commands to a group of light must arrive within 200 ms at
all destinations. The installation and operation of a building
network has different requirements. During the installation, many
stand-alone networks of a few to 100 nodes co-exist without a
connection to the backbone. During this phase, the nodes are
identified with a network identifier related to their physical
location. Devices are accessed from an installation tool to connect
them to the network in a secure fashion. During installation, the
setting of parameters of common values to enable interoperability may
be required. During operation, the networks are connected to the
backbone while maintaining the network identifier to physical
location relation. Network parameters like address and name are
stored in DNS. The names can assist in determining the physical
location of the device.
3.7. Home Automation
Home automation includes the control of lighting, heating,
ventilation, air conditioning, appliances, entertainment and home
security devices to improve convenience, comfort, energy efficiency,
and security. It can be seen as a residential extension of building
automation. However, unlike a building automation system, the
infrastructure in a home is operated in a considerably more ad-hoc
manner. While in some installations it is likely that there is no
centralized management system, akin to a Building Automation System
(BAS), available, in other situations outsourced and cloud based
systems responsible for managing devices in the home might be used.
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Home automation networks need a certain amount of configuration
(associating switches or sensors to actors) that is either provided
by electricians deploying home automation solutions, by third party
home automation service providers (e.g., small specialized companies
or home automation device manufacturers) or by residents by using the
application user interface provided by home automation devices to
configure (parts of) the home automation solution. Similarly,
failures may be reported via suitable interfaces to residents or they
might be recorded and made available to services providers in charge
of the maintenance of the home automation infrastructure.
The management responsibility lies either with the residents or it
may be outsourced to electricians and/or third parties providing
management of home automation solutions as a service. A varying
combination of electricians, service providers or the residents may
be responsible for different aspects of managing the infrastructure.
The time scale for failure detection and resolution is in many cases
likely counted in hours to days.
3.8. Transport Applications
Transport Application is a generic term for the integrated
application of communications, control, and information processing in
a transportation system. Transport telematics or vehicle telematics
are used as a term for the group of technologies that support
transportation systems. Transport applications running on such a
transportation system cover all modes of the transport and consider
all elements of the transportation system, i.e. the vehicle, the
infrastructure, and the driver or user, interacting together
dynamically. Examples for transport applications are inter and intra
vehicular communication, smart traffic control, smart parking,
electronic toll collection systems, logistic and fleet management,
vehicle control, and safety and road assistance.
As a distributed system, transport applications require an end-to-end
management of different types of networks. It is likely that
constrained devices in a network (e.g. a moving in-car network) have
to be controlled by an application running on an application server
in the network of a service provider. Such a highly distributed
network including cellular devices on vehicles is assumed to include
a wireless access network using diverse long distance wireless
technologies such as WiMAX, 3G/LTE or satellite communication, e.g.
based on an embedded hardware module. As a result, the management of
constrained devices in the transport system might be necessary to
plan top-down and might need to use data models obliged from and
defined on the application layer. The assumed device classes in use
are mainly C2 devices. In cases, where an in-vehicle network is
involved, C1 devices with limited capabilities and a short-distance
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constrained radio network, e.g. IEEE 802.15.4 might be used
additionally.
All Transport Applications will require an IT infrastructure to run
on top of, e.g., in public transport scenarios like trains, bus or
metro network infrastructure might be provided, maintained and
operated by third parties like mobile network or satellite network
operators. However, the management responsibility of the transport
application typically rests within the organization running the
transport application (in the public transport scenario, this would
typically be the public transport operator). Different aspects of
the infrastructure might also be managed by different entities. For
example, the in-car devices are likely to be installed and managed by
the manufacturer, while the public works might be responsible for the
on-road vehicular communication infrastructure used by these devices.
The back-end infrastructure is also likely to be maintained by third
party operators. As such, the NMS must be able to deal with
different network segments, each being operated and controlled by
separate entities, and enable appropriate access control and security
as well.
Depending on the type of application domain (vehicular or stationary)
and service being provided, it would be important for the NMS to be
able to function with different architectures, since different
manufacturers might have their own proprietary systems relying on a
specific Management Topology Option, as described in [COM-REQ].
Moreover, constituents of the network can be either private,
belonging to individuals or private companies, or owned by public
institutions leading to different legal and organization
requirements. Across the entire infrastructure, a variety of
constrained devices are likely to be used, and must be individually
managed. The NMS must be able to either work directly with different
types of devices, or have the ability to interoperate with multiple
different systems.
The challenges in the management of vehicles in a mobile transport
application are manifold. The up-to-date position of each node in
the network should be reported to the corresponding management
entities, since the nodes could be moving within or roaming between
different networks. Secondly, a variety of troubleshooting
information, including sensitive location information, needs to be
reported to the management system in order to provide accurate
service to the customer. Management systems dealing with mobile
nodes could possibly exploit specific patterns in the mobility of the
nodes. These patterns emerge due to repetitive vehicular usage in
scenarios like people commuting to work, logistics supply vehicles
transporting shipments between warehouses and etc. The NMS must also
be able to handle partitioned networks, which would arise due to the
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dynamic nature of traffic resulting in large inter-vehicle gaps in
sparsely populated scenarios. Since mobile nodes might roam in
remote networks, the NMS should be able to provide operating
configuration updates regardless of node location.
The constrained devices in a moving transport network might be
initially configured in a factory and a reconfiguration might be
needed only rarely. New devices might be integrated in an ad-hoc
manner based on self-management and -configuration capabilities.
Monitoring and data exchange might be necessary to do via a gateway
entity connected to the back-end transport infrastructure. The
devices and entities in the transport infrastructure need to be
monitored more frequently and can be able to communicate with a
higher data rate. The connectivity of such entities does not
necessarily need to be wireless. The time scale for detecting and
recording failures in a moving transport network is likely measured
in hours and repairs might easily take days. It is likely that a
self-healing feature would be used locally. On the other hand,
failures in fixed transport application infrastructure (e.g.,
traffic-lights, digital signage displays) is likely to be measured in
minutes so as to avoid untoward traffic incidents. As such, the NMS
must be able to deal with differing timeliness requirements based on
the type of devices.
3.9. Community Network Applications
Community networks are comprised of constrained routers in a multi-
hop mesh topology, communicating over a lossy, and often wireless
channel. While the routers are mostly non-mobile, the topology may
be very dynamic because of fluctuations in link quality of the
(wireless) channel caused by, e.g., obstacles, or other nearby radio
transmissions. Depending on the routers that are used in the
community network, the resources of the routers (memory, CPU) may be
more or less constrained - available resources may range from only a
few kilobytes of RAM to several megabytes or more, and CPUs may be
small and embedded, or more powerful general-purpose processors.
Examples of such community networks are the FunkFeuer network
(Vienna, Austria), FreiFunk (Berlin, Germany), Seattle Wireless
(Seattle, USA), and AWMN (Athens, Greece). These community networks
are public and non-regulated, allowing their users to connect to each
other and - through an uplink to an ISP - to the Internet. No fee,
other than the initial purchase of a wireless router, is charged for
these services. Applications of these community networks can be
diverse, e.g., location based services, free Internet access, file
sharing between users, distributed chat services, social networking
etc, video sharing etc.
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As an example of a community network, the FunkFeuer network comprises
several hundred routers, many of which have several radio interfaces
(with omnidirectional and some directed antennas). The routers of
the network are small-sized wireless routers, such as the Linksys
WRT54GL, available in 2011 for less than 50 Euros. These routers,
with 16 MB of RAM and 264 MHz of CPU power, are mounted on the
rooftops of the users. When new users want to connect to the
network, they acquire a wireless router, install the appropriate
firmware and routing protocol, and mount the router on the rooftop.
IP addresses for the router are assigned manually from a list of
addresses (because of the lack of autoconfiguration standards for
mesh networks in the IETF).
While the routers are non-mobile, fluctuations in link quality
require an ad hoc routing protocol that allows for quick convergence
to reflect the effective topology of the network (such as NHDP
[RFC6130] and OLSRv2 [RFC7181] developed in the MANET WG). Usually,
no human interaction is required for these protocols, as all variable
parameters required by the routing protocol are either negotiated in
the control traffic exchange, or are only of local importance to each
router (i.e. do not influence interoperability). However, external
management and monitoring of an ad hoc routing protocol may be
desirable to optimize parameters of the routing protocol. Such an
optimization may lead to a more stable perceived topology and to a
lower control traffic overhead, and therefore to a higher delivery
success ratio of data packets, a lower end-to-end delay, and less
unnecessary bandwidth and energy usage.
Different use cases for the management of community networks are
possible:
o One single Network Management Station, e.g. a border gateway
providing connectivity to the Internet, requires managing or
monitoring routers in the community network, in order to
investigate problems (monitoring) or to improve performance by
changing parameters (managing). As the topology of the network is
dynamic, constant connectivity of each router towards the
management station cannot be guaranteed. Current network
management protocols, such as SNMP and Netconf, may be used (e.g.,
using interfaces such as the NHDP-MIB [RFC6779]). However, when
routers in the community network are constrained, existing
protocols may require too many resources in terms of memory and
CPU; and more importantly, the bandwidth requirements may exceed
the available channel capacity in wireless mesh networks.
Moreover, management and monitoring may be unfeasible if the
connection between the network management station and the routers
is frequently interrupted.
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o A distributed network monitoring, in which more than one
management station monitors or manages other routers. Because
connectivity to a server cannot be guaranteed at all times, a
distributed approach may provide a higher reliability, at the cost
of increased complexity. Currently, no IETF standard exists for
distributed monitoring and management.
o Monitoring and management of a whole network or a group of
routers. Monitoring the performance of a community network may
require more information than what can be acquired from a single
router using a network management protocol. Statistics, such as
topology changes over time, data throughput along certain routing
paths, congestion etc., are of interest for a group of routers (or
the routing domain) as a whole. As of 2012, no IETF standard
allows for monitoring or managing whole networks, instead of
single routers.
3.10. Field Operations
The challenges of configuration and monitoring of networks operated
in the field by rescue and security agencies can be different from
the other use cases since the requirements and operating conditions
of such networks are quite different.
With technology advancements, field networks operated nowadays are
becomeing large and can consist of varieties of different types of
equipment that run different protocols and tools that obviously
increase complexity of these mission critical networks. In many
scenarios, configurations are, most likely, manually performed.
Furthermore, some legacy and even modern devices do not even support
IP networking. Majority of protocols and tools developed by vendors
that are being used are proprietary which makes integration more
difficult.
The main reason for this disjoint operation scenario is that most
equipment is developed with specific task requirements in mind,
rather than interoperability of the varied equipment types. For
example, the operating conditions experienced by high altitude
security equipment is significantly different from that used in
desert conditions. Similarly, search and rescue operations equipment
used in case of fire rescue has different requirements than flood
relief equipment. Furthermore, interoperation of equipment with
telecommunication equipment was not an expected outcome or in some
scenarios this may not even be desirable.
Currently, field networks operate with a fixed Network Operations
Center (NOC) that physically manages the configuration and evaluation
of all field devices. Once configured, the devices might be deployed
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in fixed or mobile scenarios. Any configuration changes required
would need to be appropriately encrypted and authenticated to prevent
unauthorized access.
Hierarchical management of devices is a common requirement in such
scenarios since local managers or operators may need to respond to
changing conditions within their purview. The level of configuration
management available at each hierarchy must also be closely governed.
Since many field operation devices are used in hostile environments,
a high failure and disconnection rate should be tolerated by the NMS,
which must also be able to deal with multiple gateways and disjoint
management protocols.
Multi-national field operations invloving search, rescue and security
are becoming increasingly common, requiring the interoperation of a
diverse set of equipment designed with different operating conditions
in mind. Furthermore, different intra- and inter-governmental
agencies are likely to have a different set of standards, best
practices, rules and regulation, and implementation approaches that
may contradict or conflict with each other. The NMS should be able
to detect these and handle them in an acceptable manner, which may
require human intervention.
4. IANA Considerations
This document does not introduce any new code-points or namespaces
for registration with IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
5. Security Considerations
This document discusses use cases for Management of Networks with
Constrained Devices. The security considerations described
throughout the companion document [COM-REQ] apply here as well.
6. Contributors
Following persons made significant contributions to and reviewed this
document:
o Ulrich Herberg (Fujitsu Laboratories of America) contributed the
Section 3.9 on Community Network Applications.
o Peter van der Stok contributed to Section 3.6 on Building
Automation.
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o Zhen Cao contributed to Section 2.2 Cellular Access Technologies.
o Gilman Tolle contributed the Section 3.4 on Automated Metering
Infrastructure.
o James Nguyen and Ulrich Herberg contributed to Section 3.10 on
Military operations.
7. Acknowledgments
Following persons reviewed and provided valuable comments to
different versions of this document:
Dominique Barthel, Carsten Bormann, Zhen Cao, Benoit Claise, Bert
Greevenbosch, Ulrich Herberg, James Nguyen, Zach Shelby, and Peter
van der Stok.
The editors would like to thank the reviewers and the participants on
the Coman maillist for their valuable contributions and comments.
8. Informative References
[RFC6130] Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc
Network (MANET) Neighborhood Discovery Protocol (NHDP)",
RFC 6130, April 2011.
[RFC6568] Kim, E., Kaspar, D., and JP. Vasseur, "Design and
Application Spaces for IPv6 over Low-Power Wireless
Personal Area Networks (6LoWPANs)", RFC 6568, April 2012.
[RFC6779] Herberg, U., Cole, R., and I. Chakeres, "Definition of
Managed Objects for the Neighborhood Discovery Protocol",
RFC 6779, October 2012.
[RFC6988] Quittek, J., Chandramouli, M., Winter, R., Dietz, T., and
B. Claise, "Requirements for Energy Management", RFC 6988,
September 2013.
[RFC7181] Clausen, T., Dearlove, C., Jacquet, P., and U. Herberg,
"The Optimized Link State Routing Protocol Version 2", RFC
7181, April 2014.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228, May 2014.
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[I-D.ietf-eman-framework]
Claise, B., Schoening, B., and J. Quittek, "Energy
Management Framework", draft-ietf-eman-framework-19 (work
in progress), April 2014.
[COM-REQ] Ersue, M., Romascanu, D., and J. Schoenwaelder,
"Management of Networks with Constrained Devices: Problem
Statement and Requirements", draft-ietf-opsawg-coman-
probstate-reqs (work in progress), February 2014.
use-cases-02
o Renamed Mobile Access Technologies section to Cellular Access
Technologies
o Changed references to mobile access technologies to now read
cellular access technologies.
o Added text to the introduction to point out that the list of use
cases is not exhaustive since others unknown to the authors might
exist.
o Updated references to take into account RFCs that have been now
published.
o Updated Environmental Monitoring section to make it clear that in
some scenarios it may not be prudent to repair devices.
o Added clarification in Infrastructure Monitoring section that
reliable communication is achieved via application layer
transactions
o Removed reference to Energy Devices from Energy Management
section, instead labeling them as devices within the context of
energy management.
o Reduced descriptive content in Energy Management section.
o Rewrote text in Energy Management section to highlight management
characteristics of Smart Meter and AMI networks.
o Added text regarding timely delivery of information, and related
management system characteristic, to the Medical Applications
section
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o Changed subnets to network segment in Building Automation section.
o Changed structure to infrastructure in Building Automation
section, and added text to highlight associated deployment
difficulties.
o Removed Trickle timer as example of common values to be set in
Building Automation section.
o Added text regarding the possible availability of outsourced and
cloud based management systems for Home Automation.
o Added text to Transport Applications section to highlight the
requirement of IT infrastructure for such applications to function
on top of.
o Merged the Transport Applications and Vehicular Networks section
together. Following changes to the Vehicular Networks section
were merged back into Transport Applications
* Replaced wireless last hops with wireless access to vehicles in
Vehicular Networks.
* Expanded proprietary systems to "systems relying on a specific
Management Topology Option, as described in [COM-REQ]." within
Vehicular Networks section.
* Added text regarding mobility patterns to Vehicular Networks.
o Changed the Military Operations use case to Field Operations and
edited the text to be suitable to such scenarios.
use-cases-01
o Reordered some use cases to improve the flow.
o Added "Vehicular Networks".
o Shortened the Military Operations use case.
o Started adding substance to the security considerations section.
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cases-00
o Reduced the terminology section for terminology addressed in the
LWIG and Coman Requirements drafts. Referenced the other drafts.
o Checked and aligned all terminology against the LWIG terminology
draft.
o Spent some effort to resolve the intersection between the
Industrial Application, Home Automation and Building Automation
use cases.
o Moved section section 3. Use Cases from the companion document
[COM-REQ] to this draft.
o Reformulation of some text parts for more clarity.
o Extended the terminology section and removed some of the
terminology addressed in the new LWIG terminology draft.
Referenced the LWIG terminology draft.
o Moved Section 1.3. on Constrained Device Classes to the new LWIG
terminology draft.
o Class of networks considering the different type of radio and
communication technologies in use and dimensions extended.
o Extended the Problem Statement in Section 2. following the
requirements listed in Section 4.
o Following requirements, which belong together and can be realized
with similar or same kind of solutions, have been merged.
* Distributed Management and Peer Configuration,
* Device status monitoring and Neighbor-monitoring,
* Passive Monitoring and Reactive Monitoring,
* Event-driven self-management - Self-healing and Periodic self-
management,
* Authentication of management systems and Authentication of
managed devices,
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* Access control on devices and Access control on management
systems,
* Management of Energy Resources and Data models for energy
management,
* Software distribution (group-based firmware update) and Group-
based provisioning.
o Deleted the empty section on the gaps in network management
standards, as it will be written in a separate draft.
o Added links to mentioned external pages.
o Added text on OMA M2M Device Classification in appendix.
o Extended the terminology section.
o Added additional text for the use cases concerning deployment
type, network topology in use, network size, network capabilities,
radio technology, etc.
o Added examples for device classes in a use case.
o Added additional text provided by Cao Zhen (China Mobile) for
Mobile Applications and by Peter van der Stok for Building
Automation.
o Added the new use cases 'Advanced Metering Infrastructure' and
'MANET Concept of Operations in Military'.
o Added the section 'Managing the Constrainedness of a Device or
Network' discussing the needs of very constrained devices.
o Added a note that the requirements in [COM-REQ] need to be seen as
standalone requirements and the current document does not
recommend any profile of requirements.
o Added a section in [COM-REQ] for the detailed requirements on
constrained management matched to management tasks like fault,
monitoring, configuration management, Security and Access Control,
Energy Management, etc.
o Solved nits and added references.
o Added Appendix A on the related development in other bodies.
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o Added Appendix B on the work in related research projects.
o Splitted the section on 'Networks of Constrained Devices' into the
sections 'Network Topology Options' and 'Management Topology
Options'.
o Added the use case 'Community Network Applications' and 'Mobile
Applications'.
o Provided a Contributors section.
o Extended the section on 'Medical Applications'.
o Solved nits and added references.
Authors' Addresses
Mehmet Ersue (editor)
Nokia Networks
Email: mehmet.ersue@nsn.com
Dan Romascanu
Avaya
Email: dromasca@avaya.com
Juergen Schoenwaelder
Jacobs University Bremen
Email: j.schoenwaelder@jacobs-university.de
Anuj Sehgal
Jacobs University Bremen
Email: s.anuj@jacobs-university.de
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