draft-ietf-roll-home-routing-reqs-02.txt   draft-ietf-roll-home-routing-reqs-03.txt 
Networking Working Group A. Brandt Networking Working Group A. Brandt
Internet Draft Zensys, Inc. Internet Draft Zensys, Inc.
Intended status: Informational G. Porcu Intended status: Informational G. Porcu
Expires: January 2009 Telecom Italia Expires: January 2009 Telecom Italia
July 14, 2008 September 11, 2008
Home Automation Routing Requirement in Low Power and Lossy Networks Home Automation Routing Requirement in Low Power and Lossy
draft-ietf-roll-home-routing-reqs-02 Networks
draft-ietf-roll-home-routing-reqs-03
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Abstract Abstract
This document presents home control and automation application This document presents home control and automation application
specific requirements for ROuting in Low power and Lossy networks specific requirements for Routing Over Low power and Lossy
(ROLL). In a modern home, a high number of wireless devices are used networks (ROLL). In a modern home, a high number of wireless
for a wide set of purposes. Examples include lighting control, devices are used for a wide set of purposes. Examples include
heating control, sensors, leak detectors, healthcare systems and actuators (relay, light dimmer, heating valve), sensors (wall
advanced remote controls. Because such devices only cover a limited switch, water leak, blood pressure) and advanced controllers.
radio range, multi-hop routing is often required. The aim of this Because such devices only cover a limited radio range, routing is
document is to specify the routing requirements for networks often required. The aim of this document is to specify the routing
comprising such constrained devices in a home network environment. requirements for networks comprising such constrained devices in a
home control and automation environment.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
document are to be interpreted as described in RFC-2119 [RFC2119]. in this document are to be interpreted as described in RFC-2119
[RFC2119].
Table of Contents Table of Contents
1. Terminology....................................................3 Terminology......................................................3
2. Introduction...................................................3 1. Introduction..................................................5
3. Home automation applications...................................4 2. Home Automation Applications..................................6
3.1. Turning off the house when leaving........................4 2.1. Lighting Application In Action...........................6
3.2. Energy conservation and optimizing energy consumption.....5 2.2. Energy Conservation and Optimizing Energy Consumption....6
3.3. Moving a remote control around............................5 2.3. Moving a Remote Control Around...........................7
3.4. Adding a new lamp module to the system....................6 2.4. Adding A New Module To The System........................7
3.5. Controlling battery operated window shades................6 2.5. Controlling Battery Operated Window Shades...............8
3.6. Remote video surveillance.................................6 2.6. Remote Video Surveillance................................8
3.7. Healthcare................................................7 2.7. Healthcare...............................................8
3.7.1. At-home health reporting.............................7 2.7.1. At-home Health Reporting............................9
3.7.2. At-home health monitoring............................8 2.7.2. At-home Health Monitoring...........................9
3.7.3. Healthcare routing considerations....................8 2.8. Alarm Systems............................................9
3.8. Alarm systems.............................................8 3. Unique Routing Requirements of Home Automation Applications..10
3.9. Battery-powered devices...................................9 3.1. Support of Groupcast....................................11
4. Unique requirements of home automation applications............9 3.2. Constraint-based Routing................................12
4.1. Support of groupcast......................................9 3.3. Support of Mobility.....................................12
4.2. Constraint-based Routing.................................10 3.4. Sleeping Nodes..........................................13
4.3. Support of Mobility......................................10 3.5. Healthcare Routing......................................13
4.4. Support of Periodical Scanning...........................11 3.6. Scalability.............................................13
4.5. Scalability..............................................11 3.7. Convergence Time........................................14
4.6. Convergence Time.........................................11 3.8. Manageability...........................................14
4.7. Manageability............................................12 3.9. Stability...............................................14
5. Traffic Pattern...............................................12 4. Traffic Pattern..............................................14
6. Open issues...................................................13 5. Open Issues..................................................15
7. Security Considerations.......................................13 6. Security Considerations......................................15
8. IANA Considerations...........................................13 7. IANA Considerations..........................................15
9. Acknowledgments...............................................13 8. Acknowledgments..............................................15
10. References...................................................14 9. References...................................................16
10.1. Normative References....................................14 9.1. Normative References....................................16
10.2. Informative References..................................14 9.2. Informative References..................................17
Disclaimer of Validity...........................................15 Disclaimer of Validity..........................................18
1. Terminology
ROLL: ROuting in Low-power and Lossy networks Terminology
ROLL device: A ROLL network node with constrained CPU and memory ROLL: Routing Over Low-power and Lossy networks
resources; potentially constrained power resources. A ROLL node may be classified as sensor, actuator
or controller.
Access Point: The access point is an infrastructure device that Access Point: The access point is an infrastructure device that
connects the low power and lossy network system to the connects a ROLL network to the Internet or some
Internet, possibly via a customer premises local area backbone network.
network (LAN).
Actuator: Network node which performs some physical action.
Dimmers and relays are examples of actuators.
If sufficiently powered, actuator nodes may
participate in routing network messages.
Channel: Radio frequency band used to carry network packets.
Controller: Network node that controls actuators. Control
decisions may be based on sensor readings, sensor
events, scheduled actions or incoming commands from
the Internet or other backbone networks.
If sufficiently powered, controller nodes may
participate in routing network messages.
Downstream: Data direction traveling from a Local Area Network
(LAN) to a Personal Area Network (PAN) device.
DR: Demand-Response
The mechanism of users adjusting their power
consumption in response to actual pricing of power.
DSM: Demand Side Management
Process allowing power utilities to enable and
disable loads in consumer premises. Where DR relies
on voluntary action from users, DSM may be based on
enrollment in a formal program.
LAN: Local Area Network. LAN: Local Area Network.
PAN: Personal Area Network. PAN: Personal Area Network.
A geographically limited wireless network based on A geographically limited wireless network based on
e.g. 802.15.4 or Z-Wave radio. e.g. 802.15.4 or Z-Wave radio.
Channel: Radio frequency band used to transmit a modulated PDA Personal Digital Assistant. A small, handheld
signal carrying packets. computer.
Downstream: Data direction traveling from a Local Area Network PLC Power Line Communication
(LAN) to a Personal Area Network (PAN) device.
Upstream: Data direction traveling from a PAN to a LAN device. RAM Random Access Memory
Sensor: A PAN device that measures data and/or detects an Sensor: Network node that measures data and/or detects an
event. event.
The sensor may generate a trap message to notify a
controller or directly activate an actuator.
If sufficiently powered, sensor nodes may
participate in routing network messages.
2. Introduction Upstream: Data direction traveling from a PAN to a LAN
device.
This document presents the home control and automation application 1. Introduction
specific requirements for Routing in Low power and Lossy Networks
(ROLL). In a modern home, a high number of wireless devices are used
for a wide set of purposes. Examples include lighting control
modules, heating control panels, light sensors, temperature sensors,
gas/water leak detectors, motion detectors, video surveillance,
healthcare systems and advanced remote controls. Basic home control
modules such as wall switches and plug-in modules may be turned into
an advanced home automation solution via the use of an IP-enabled
application responding to events generated by wall switches, motion
sensors, light sensors, rain sensors, and so on.
Because such devices only cover a limited radio range, multi-hop This document presents home control and automation application
routing is often required. These devices are usually highly specific requirements for Routing Over Low power and Lossy
constrained in term of resources such as battery and memory and networks (ROLL). In a modern home, a high number of wireless
operate in unstable environments. Persons moving around in a house, devices are used for a wide set of purposes. Examples include
opening or closing a door or starting a microwave oven affect the actuators (relay, light dimmer, heating valve), sensors (wall
reception of weak radio signals. Reflection and absorption may cause switch, water leak, blood pressure) and advanced controllers.
a reliable radio link to turn unreliable for a period of time and Basic home control modules such as wall switches and plug-in
then being reusable again, thus the term "lossy". modules may be turned into an advanced home automation solution
via the use of an IP-enabled application responding to events
generated by wall switches, motion sensors, light sensors, rain
sensors, and so on.
Unlike other categories of PANs, the connected home area is very much Network nodes may be sensors and actuators at the same time. An
consumer-oriented. The implications on network nodes in this aspect, example is a wall switch for replacement in existing buildings.
is that devices are very cost sensitive, which leads to resource- The push buttons may generate events for a controller node or for
activating other actuator nodes. At the same time, a built-in
relay may act as actuator for a controller or other remote
sensors.
Because ROLL nodes only cover a limited radio range, routing is
often required. These devices are usually highly constrained in
term of resources such as battery and memory and operate in
unstable environments. Persons moving around in a house, opening
or closing a door or starting a microwave oven affect the
reception of weak radio signals. Reflection and absorption may
cause a reliable radio link to turn unreliable for a period of
time and then being reusable again, thus the term "lossy".
Unlike other categories of PANs, the connected home area is very
much consumer-oriented. The implication on network nodes is that
devices are very cost sensitive, which leads to resource-
constrained environments having slow CPUs and small memory constrained environments having slow CPUs and small memory
footprints. At the same time, nodes have to be physically small which footprints. At the same time, nodes have to be physically small
puts a limit to the physical size of the battery; and thus, the which puts a limit to the physical size of the battery; and thus,
battery capacity. As a result, it is common for low-power sensor- the battery capacity. As a result, it is common for low-power
style nodes to shut down radio and CPU resources for most of the sensor-style nodes to shut down radio and CPU resources for most
time. Often, the radio uses the same power for listening as for of the time. The radio tends to use the same power for listening
transmitting. as for transmitting
Section 3 describes a few typical use cases for home automation Section 2 describes a few typical use cases for home automation
applications. Section 4 discusses the routing requirements for applications. Section 3 discusses the routing requirements for
networks comprising such constrained devices in a home network networks comprising such constrained devices in a home network
environment. These requirements may be overlapping requirements environment. These requirements may be overlapping requirements
derived from other application-specific requirements. derived from other application-specific routing requirements. A
full list of requirements documents may be found in the end of the
document.
3. Home automation applications 2. Home Automation Applications
Home automation applications represent a special segment of networked Home automation applications represent a special segment of
wireless devices with its unique set of requirements. To facilitate networked devices with its unique set of requirements.
the requirements discussion in Section 4, this section lists a few Historically, such applications used wired networks or power line
typical use cases of home automation applications. New applications communication (PLC), but wireless solutions have emerged; allowing
are being developed at a high pace and this section does not mean to existing buildings to be upgraded more easily.
be exhaustive. Most home automation applications tend to be running
some kind of command/response protocol. The command may come from
several places. For instance a lamp may be turned on, not only be a
wall switch but also from a movement sensor.
3.1. Turning off the house when leaving To facilitate the requirements discussion in Section 3, this
section lists a few typical use cases of home automation
applications. New applications are being developed at a high pace
and this section does not mean to be exhaustive. Most home
automation applications tend to be running some kind of
command/response protocol. The command may come from several
places.
Using the direct analogy to an electronic car key, a house owner may 2.1. Lighting Application In Action
activate the "leaving home" function from an electronic house key,
mobile phone, etc. For the sake of visual impression, all lights
should turn off at the same time. At least, it should appear to
happen at the same time. A well-known problem in wireless home
automation is the "popcorn effect": Lamps are turned on one at a
time, at a rate so slow that it is clearly visible. Some existing
home automation solutions use a clever mix of a "subnet groupcast"
message with no acknowledgement and no forwarding before sending
acknowledged singlecast messages to each lighting device.
The controller forms the groups and decides which nodes should A lamp may be turned on, not only by a wall switch but also by a
receive "turn-off" or "turn-on" requests. movement sensor. The wall switch module may itself be a push-
button sensor and an actuator at the same time. This will often be
the case when upgrading existing buildings as existing wiring is
not prepared for automation.
3.2. Energy conservation and optimizing energy consumption One event may cause many actuators to be activated at the same
time.
Using the direct analogy to an electronic car key, a house owner
may activate the "leaving home" function from an electronic house
key, mobile phone, etc. For the sake of visual impression, all
lights should turn off at the same time. At least, it should
appear to happen at the same time. A well-known problem in
wireless home automation is the "popcorn effect": Lamps are turned
on one at a time, at a rate so slow that it is clearly visible.
Some existing home automation solutions use a clever mix of a
"subnet groupcast" message in direct range with no acknowledgement
before sending acknowledged singlecast messages to each device.
Parts of the world using air conditioning may let shades go down and The controller forms the group and decides which nodes should
turn off the AC device when leaving home. Air conditioning may start receive a message.
by timer or via motion sensor when the owner returns home. The owner
may even activate the air conditioning via cell phone before getting
home.
Geographical areas using central heating may turn off heating when 2.2. Energy Conservation and Optimizing Energy Consumption
not at home and use a reduced temperature during night time.
The power grid may experience periods where more wind-generated power In order to save energy, air conditioning, central heating, window
is produced than is needed. Typically this may happen during night shades etc. may be controlled by timers, motion sensors or
hours. The washing machine and dish washer may just as well work remotely via internet or cell. Central heating may also be set to
a reduced temperature during night time.
The power grid may experience periods where more wind-generated
power is produced than is needed. Typically this may happen during
night hours.
In periods where electricity demands exceed available supply,
appliances such as air conditioning, climate control systems,
washing machines etc. can be turned off to avoid overloading the
power grid.
This is known as Demand-Side Management (DSM).
Remote control of household appliances is well-suited for this
application.
The start/stop decision for the appliances can also be regulated
by dynamic power pricing information obtained from the electricity
utility companies. This method called Demand-Response (DR) works
by motivation of users via pricing, bonus points, etc. For
example, the washing machine and dish washer may just as well work
while power is cheap. The electric car should also charge its while power is cheap. The electric car should also charge its
batteries on cheap power. batteries on cheap power.
In periods where electricity demands exceed available supply, In order to achieve effective electricity savings, the energy
appliances such as air conditioning, climate control systems, washing monitoring application must guarantee that the power consumption
machines etc. can be turned off to avoid overloading the power grid. of the ROLL devices is much lower than that of the appliance
Wireless remote control of the household appliances is well-suited itself.
for this application. The start/stop decision for the appliances can
be regulated by dynamic power pricing information obtained from the
electricity utility companies. Moreover, in order to achieve
effective electricity savings, the energy monitoring application
running on the Wireless Sensor Network (WSN) must guarantee that the
power consumption of the ROLL devices is much lower than that of the
appliance itself.
Most of these applications are mains powered and are thus ideal for Most of these appliances are mains powered and are thus ideal for
providing reliable, always-on routing resources. Battery-powered providing reliable, always-on routing resources. Battery-powered
nodes, by comparison, are constrained routing resources and may only nodes, by comparison, are constrained routing resources and may
provide reliable routing under some circumstances. only provide reliable routing under some circumstances.
3.3. Moving a remote control around 2.3. Moving a Remote Control Around
A remote control is a typical example of a mobile device in a home A remote control is a typical example of a mobile device in a home
automation network. An advanced remote control may be used for automation network. An advanced remote control may be used for
dimming the light in the dining room while eating and later on, dimming the light in the dining room while eating and later on,
turning up the music while doing the dishes in the kitchen. Reaction turning up the music while doing the dishes in the kitchen.
must appear to be instant (within a few hundred milliseconds) even Reaction must appear to be instant (within a few hundred
when the remote control has moved to a new location. The remote milliseconds) even when the remote control has moved to a new
control may be communicating to either a central home automation location. The remote control may be communicating to either a
controller or directly to the lamps and the media center. central home automation controller or directly to the lamps and
the media center.
3.4. Adding a new lamp module to the system 2.4. Adding A New Module To The System
Small-size, low-cost modules may have no user interface except for a Small-size, low-cost modules may have no user interface except for
single button. Thus, an automated inclusion process is needed for a single button. Thus, an automated inclusion process is needed
controllers to find new modules. Inclusion covers the detection of for controllers to find new modules. Inclusion covers the
neighbors and assignment of a unique node ID. Inclusion should be detection of neighbors and assignment of a unique node ID.
completed within a few seconds. Inclusion should be completed within a few seconds.
Distribution of unique addresses is usually performed by a central If assignment of unique addresses is performed by a central
controller. In this case, it must be possible to route the inclusion controller, it must be possible to route the inclusion request
request from the joining node to the central controller even before from the joining node to the central controller before the joining
the joining node is assigned a unique address. node has been included in the network.
3.5. Controlling battery operated window shades 2.5. Controlling Battery Operated Window Shades
In consumer premises, window shades are often battery-powered as In consumer premises, window shades are often battery-powered as
there is no access to mains power over the windows. For battery there is no access to mains power over the windows. For battery
conservation purposes, the receiver is sleeping most of the time. A conservation purposes, such an actuator node is sleeping most of
home automation controller sending commands to window shades via ROLL the time. A controller sending commands to a sleeping actuator
devices will have no problems delivering the packet to the router, node via ROLL devices will have no problems delivering the packet
but the router may have to wait for some time before the command can to the nearest powered router, but that router may experience a
be delivered to the window shades if the receiver is sleeping; e.g. delay until the next wake-up time before the command can be
up to 250ms. delivered.
3.6. Remote video surveillance 2.6. Remote Video Surveillance
Remote video surveillance is a fairly classic application for Home Remote video surveillance is a fairly classic application for Home
networking providing the ability for the end user to get a video networking providing the ability for the end user to get a video
stream from a Web Cam reached via the Internet, which can be stream from a Web Cam reached via the Internet. The video stream
triggered by the end-user that has received an alarm from a movement may be triggered by the end-user after receiving an alarm from a
sensor or smoke detector - or the user simply wants to check the home sensor (movement or smoke detector) or the user simply wants to
status via video. check the home status via video.
Note that in the former case, more than likely, there will be a form Note that in the former case, more than likely, there will be a
of inter-device communication: indeed, upon detecting some movement form of inter-device communication: Upon detecting some movement
in the home, the movement sensor may send a request to the light in the home, the movement sensor may send a request to the light
controller to turn-on the lights, to the Web Cam to start a video controller to turn on the lights, to the Web Cam to start a video
stream that would then be directed to the end user (cell phone, PDA) stream that would then be directed to the end user's cell phone or
via the Internet. Personal Digital Assistant (PDA) via the Internet.
By contrast with other applications, e.g. industrial sensors where In contrast to other applications, e.g. industrial sensors, where
data would mainly be originated by sensor to a sink and vice versa, data would mainly be originated by sensor to a sink and vice
this scenario implicates a direct inter-device communication between versa, this scenario implicates a direct inter-device
ROLL devices. communication between ROLL devices.
3.7. Healthcare 2.7. Healthcare
By adding communication capability to devices, patients and elderly By adding communication capability to devices, patients and
citizens may be able to do simple measurements at home. Thanks to elderly citizens may be able to do simple measurements at home.
online devices, a doctor can keep an eye on the patient's health and Thanks to online devices, a doctor can keep an eye on the
receive warnings if a new trend is discovered by automated filters. patient's health and receive warnings if a new trend is discovered
by automated filters.
Fine-grained daily measurements presented in proper ways may allow Fine-grained daily measurements presented in proper ways may allow
the doctor to establish a more precise diagnosis. the doctor to establish a more precise diagnosis.
Such applications may be realized as wearable products which Such applications may be realized as wearable products which
frequently do a measurement and automatically deliver the result to a frequently do a measurement and automatically deliver the result
data sink locally or over the Internet. to a data sink locally or over the Internet.
Applications falling in this category are referred to as at-home Applications falling in this category are referred to as at-home
health reporting. Whether measurements are done in a fixed interval health reporting. Whether measurements are done in a fixed
or if they are manually activated, they leave all processing to the interval or if they are manually activated, they leave all
receiving data sink. processing to the receiving data sink.
A more active category of applications may send an alarm if some A more active category of applications may send an alarm if some
alarm condition is triggered. This category of applications is alarm condition is triggered. This category of applications is
referred to as at-home health monitoring. Measurements are referred to as at-home health monitoring. Measurements are
interpreted in the device and may cause reporting of an event if an interpreted in the device and may cause reporting of an event if
alarm is triggered. an alarm is triggered.
Many implementations may overlap both categories. Many implementations may overlap both categories.
3.7.1. At-home health reporting 2.7.1. At-home Health Reporting
Applications might include: Applications might include:
o Temperature o Temperature
o Weight o Weight
o Blood pressure o Blood pressure
o Insulin level o Insulin level
Measurements may be stored for long term statistics. At the same Measurements may be stored for long term statistics. At the same
time, a critically high blood pressure may cause the generation of an time, a critically high blood pressure may cause the generation of
alarm report. Refer to 3.7.2. an alarm report. Refer to 2.7.2.
To avoid a high number of request messages, nodes may be configured To avoid a high number of request messages, nodes may be
to autonomously do a measurement and send a report in intervals. configured to autonomously do a measurement and send a report in
intervals.
3.7.2. At-home health monitoring 2.7.2. At-home Health Monitoring
An alarm event may become active e.g. if the measured blood pressure An alarm event may become active e.g. if the measured blood
exceeds a threshold or if a person falls to the ground. pressure exceeds a threshold or if a person falls to the ground.
Alarm conditions must be reported with the highest priority and
timeliness.
Applications might include: Applications might include:
o Temperature o Temperature
o Weight o Weight
o Blood pressure o Blood pressure
o Insulin level o Insulin level
o Electrocardiogram (ECG) o Electrocardiogram (ECG)
o Position tracker o Position tracker
3.7.3. Healthcare routing considerations 2.8. Alarm Systems
From a ROLL perspective, all the above-mentioned applications may run
on battery. They may also be portable and therefore need to locate a
new neighbor router on a frequent basis.
Not being powered most of the time, the nodes should not be used as
routing nodes. However, sleeping, battery-powered nodes may be
involved in routing. Examples include cases where a person falls
during a power blackout. In that case it may be that no mains-powered
routers are available for forwarding the alarm message to a (battery-
backed) internet gateway located out of direct range.
Delivery of measurement data has a more relaxed requirement for route
discovery time compared to a remote control. On the other hand, it is
critical that a "person fell" alarm is actually delivered in the end.
3.8. Alarm systems
A home security alarm system is comprised of various devices like A home security alarm system is comprised of various sensors
vibration detectors, fire or carbon monoxide detection system, door (vibration, fire or carbon monoxide, door/window, glass-break,
or window contacts, glass-break detector, presence sensor, panic presence, panic button, etc.).
button, home security key.
Some smoke alarms are battery powered and at the same time mounted in Some smoke alarms are battery powered and at the same time mounted
a high place. Battery-powered safety devices should only be used for in a high place. Battery-powered safety devices should only be
routing if no other alternatives exist to avoid draining the battery. used for routing if no other alternatives exist to avoid draining
A smoke alarm with a drained battery does not provide a lot of the battery. A smoke alarm with a drained battery does not provide
safety. Also, it may be inconvenient to exchange battery in a smoke a lot of safety. Also, it may be inconvenient to exchange battery
alarm. in a smoke alarm.
Alarm system applications may have both a synchronous and an Alarm system applications may have both a synchronous and an
asynchronous behavior; i.e. they may be periodically queried by a asynchronous behavior; i.e. they may be periodically queried by a
central control application (e.g. for a periodical refreshment of the central control application (e.g. for a periodical refreshment of
network state), or send a message to the control application on their the network state), or send a message to the control application
own initiative basing upon the status of the environment they on their own initiative.
monitor.
When a node (or a group of nodes) identifies a risk situation (e.g. When a node (or a group of nodes) identifies a risk situation
intrusion, smoke, fire), it sends an alarm message to the control (e.g. intrusion, smoke, fire), it sends an alarm message to a
centre that could autonomously forward it via Internet or interact central controller that could autonomously forward it via Internet
with the WSN (e.g. trying to obtain more detailed information or or interact with other network nodes (e.g. try to obtain more
asking to other nodes close to the alarm event). Alarm messages detailed information or ask other nodes close to the alarm event).
have, obviously, strict low-latency requirements.
Finally, routing via battery-powered nodes may be very slowly Finally, routing via battery-powered nodes may be very slow if the
reacting if the nodes are sleeping most of the time (they could nodes are sleeping most of the time (they could appear
appear unresponsive to the alarm detection). To ensure fast message unresponsive to the alarm detection). To ensure fast message
delivery and avoid battery drain, routing should be avoided via this delivery and avoid battery drain, routing should be avoided via
category of devices. sleeping devices.
3.9. Battery-powered devices 3. Unique Routing Requirements of Home Automation Applications
For convenience and low operational costs, power consumption of Home automation applications have a number of specific routing
consumer products must be kept at a very low level to achieve a long requirements related to the set of home networking applications
battery lifetime. One implication of this fact is that RAM memory is and the perceived operation of the system.
limited and it may even be powered down; leaving only a few 100 bytes
of RAM alive during the sleep phase.
The use of battery powered devices reduces installation costs and The relations of use cases to requirements are outlined in the
does enable installation of devices even where main power lines are table below:
not available. On the other hand, in order to be cost effective and
efficient, the devices have to maximize the sleep phase with a duty
cycle lower than 10%.
4. Unique requirements of home automation applications +------------------------------- +-----------------------------+
| Use case | Requirement |
+------------------------------- +-----------------------------+
|2.1. Lighting Application In |3.1. Support of Groupcast |
|Action |3.3. Support of Mobility |
| |3.6. Scalability |
+------------------------------- +-----------------------------+
|2.2. Energy Conservation and |3.2. Constraint-based Routing|
|Optimizing Energy Consumption | |
+------------------------------- +-----------------------------+
|2.3. Moving a Remote Control |3.3. Support of Mobility |
|Around |3.7. Convergence Time |
+------------------------------- +-----------------------------+
|2.4. Adding A New Module To The |3.7. Convergence Time |
|System |3.8. Manageability |
+------------------------------- +-----------------------------+
|2.5. Controlling Battery |3.4. Sleeping Nodes |
|Operated Window Shades | |
+------------------------------- +-----------------------------+
|2.7. Healthcare |3.2. Constraint-based Routing|
| |3.3. Support of Mobility |
| |3.5. Healthcare Routing |
| |3.7. Convergence Time |
+------------------------------- +-----------------------------+
|2.8. Alarm Systems |3.6. Scalability |
| |3.7. Convergence Time |
+------------------------------- +-----------------------------+
Home automation applications have a number of specific requirements 3.1. Support of Groupcast
related to the set of home networking applications and the perceived
operation of the system.
4.1. Support of groupcast +----------------------------------------------------------+
| Author's note: |
| The support of groupcast only has implication on the |
| addressing scheme and as such, it is outside the scope |
| of this document that focuses on routing requirements. |
| Nevertheless, it is an important parameter for the |
| definition of the ROLL layer interface towards various |
| layer two technologies for home control. |
| |
| Should a dedicated application-specific document be |
| created for such details? |
+----------------------------------------------------------+
Groupcast, in the context of home automation, is defined as the Groupcast, in the context of home automation, is defined as the
ability to simultaneously transmit a message to a group of recipients ability to simultaneously transmit a message to a group of
without prior interaction with the group members (i.e. group setup). recipients without prior interaction with the group members (i.e.
A use-case for groupcast is given in Section 3.1. group setup). A use-case for groupcast is given in Section 2.1.
Broadcast and groupcast in home automation MAY be used to deliver the Broadcast and groupcast in home automation MAY be used to achieve
illusion that all recipients respond simultaneously. Distant simultaneous reaction from a group of nodes.
recipients out of direct range may not react to the (unacknowledged)
groupcast. Acknowledged unicast delivery MUST be used subsequently.
The support of unicast, groupcast and broadcast also has an It SHOULD be to possible to address a group of receivers known by
implication on the addressing scheme and are outside the scope of the sender even if the receivers do not know that they have been
this document that focuses on the routing requirements aspects. grouped by the sender.
It MUST be to possible to address a group of receivers known by the 3.2. Constraint-based Routing
sender even if the receivers do not know that they have been grouped
by the sender.
4.2. Constraint-based Routing For convenience and low operational costs, power consumption of
consumer products must be kept at a very low level to achieve a
long battery lifetime. One implication of this fact is that Random
Access Memory (RAM) is limited and it may even be powered down;
leaving only a few 100 bytes of RAM alive during the sleep phase.
Simple battery-powered nodes such as movement sensors on garage doors The use of battery powered devices reduces installation costs and
and rain meters may not be able to assist in routing. Depending on does enable installation of devices even where main power lines
the node type, the node never listens at all, listens rarely or makes are not available. On the other hand, in order to be cost
contact on demand to a pre-configured target node. Attempting to effective and efficient, the devices have to maximize the sleep
communicate to such nodes may require long time before getting a phase with a duty cycle lower than 1%.
response.
Other battery-powered nodes may have the capability to participate in Some devices only wake up in response to an event, e.g. a push
routing. The routing protocol should either share the load between button.
nodes to preserve battery or only route via mains-powered nodes if
possible. The most reliable routing resource may be a battery-backed, Simple battery-powered nodes such as movement sensors on garage
mains-powered smoke alarm. doors and rain sensors may not be able to assist in routing.
Depending on the node type, the node never listens at all, listens
rarely or makes contact on demand to a pre-configured target node.
Attempting to communicate to such nodes may at best require long
time before getting a response.
Other battery-powered nodes may have the capability to participate
in routing. The routing protocol SHOULD route via mains-powered
nodes if possible.
The routing protocol MUST support constraint-based routing taking The routing protocol MUST support constraint-based routing taking
into account node properties (CPU, memory, level of energy, sleep into account node properties (CPU, memory, level of energy, sleep
intervals, safety/convenience of changing battery). intervals, safety/convenience of changing battery).
4.3. Support of Mobility 3.3. Support of Mobility
In a home environment, although the majority of devices are fixed In a home environment, although the majority of devices are fixed
devices, there is still a variety of mobile devices: for example a devices, there is still a variety of mobile devices: for example a
multi-purpose remote control is likely to move. Another example of multi-purpose remote control is likely to move. Another example of
mobile devices is wearable healthcare devices. mobile devices is wearable healthcare devices.
While healthcare devices delivering measurement results can tolerate While healthcare devices delivering measurement results can
route discovery times measured in seconds, a remote control appears tolerate route discovery times measured in seconds, a remote
unresponsive if using more than 0.5 seconds to e.g. pause the music. control appears unresponsive if using more than 0.5 seconds to
e.g. pause the music.
While, in theory, all battery-powered devices and mains-powered plug- While, in theory, all battery-powered devices and mains-powered
in modules may be moved, the predominant case is that the sending plug-in modules may be moved, the predominant case is that the
node has moved while the rest of the network has not changed. sending node has moved while the rest of the network has not
changed.
The routing protocol MUST provide mobility with convergence time The routing protocol MUST provide mobility with convergence time
below 0.5 second if only the sender has moved. below 0.5 second if only the sender has moved.
A non-responsive node can either be caused by 1) a failure in the A non-responsive node can either be caused by 1) a failure in the
node, 2) a failed link on the path to the node or 3) a moved node. In node, 2) a failed link on the path to the node or 3) a moved node.
the first two cases, the node can be expected to reappear at roughly In the first two cases, the node can be expected to reappear at
the same location in the network, whereas it can return anywhere in roughly the same location in the network, whereas it can return
the network in the latter case. The search strategy in the routing anywhere in the network in the latter case.
protocol will behave differently depending on this expectation. The
routing protocol SHOULD make use of the fact that if not being able
to deliver a packet, it is most likely that the sending node moved;
rather than a failure occurred in that node or in a link on the path
towards it.
4.4. Support of Periodical Scanning 3.4. Sleeping Nodes
The routing protocol MUST support the recognition of neighbors and Sleeping nodes may appear to be non-responsive. The routing
periodical scanning. This process SHOULD preserve energy capacity as protocol MUST take into account the delivery time to a sleeping
much as possible. target node.
(Derived from use case 3.8. Alarm Systems) The wake-up interval of a sleeping node MUST be less than one
second.
4.5. Scalability 3.5. Healthcare Routing
Because most health care applications may run on battery, this
leads to specific requirements for the routing protocol. Most
health care applications may also be portable and therefore need
to locate a new neighbor router on a frequent basis.
Not being powered most of the time, the nodes should not be used
as routing nodes. However, battery-powered nodes may be involved
in routing. Examples include cases where a person falls during a
power blackout. In that case it may be that no mains-powered
routers are available for forwarding the alarm message to a
(battery-backed) internet gateway located out of direct range.
Delivery of measurement data has a more relaxed requirement for
route discovery time compared to a remote control. On the other
hand, it is critical that a "person fell" alarm is actually
delivered.
3.6. Scalability
Looking at the number of wall switches, power outlets, sensors of Looking at the number of wall switches, power outlets, sensors of
various nature, video equipment and so on in a modern house, it seems various nature, video equipment and so on in a modern house, it
quite realistic that hundreds of low power devices may form a home seems quite realistic that hundreds of low power devices may form
automation network in a fully populated "smart" home. Moving towards a home automation network in a fully populated "smart" home.
professional building automation, the number of such devices may be Moving towards professional building automation, the number of
in the order of several thousands. such devices may be in the order of several thousands.
Thus, the routing protocol MUST support 250 devices in a subnet. The routing protocol MUST support 250 devices in the network.
The routing protocol SHOULD support 2500 devices in a subnet.
4.6. Convergence Time 3.7. Convergence Time
A home automation Personal Area Network (PAN) is subject to various A wireless home automation network is subject to various
instability due to signal strength variation, moving persons and the instabilities due to signal strength variation, moving persons and
like. Furthermore, as the number of devices increases, the the like. Furthermore, as the number of devices increases, the
probability of a node failure also increases. probability of a node failure also increases.
Measured from the transmission of a packet, the following convergence Measured from the transmission of a packet, the following
time requirements apply. convergence time requirements apply.
The routing protocol MUST converge within 0.5 second if no nodes have The routing protocol MUST converge within 0.5 second if no nodes
moved. have moved.
The routing protocol MUST converge within 2 seconds if the The routing protocol MUST converge within 2 seconds if the
destination node of the packet has moved. destination node of the packet has moved.
4.7. Manageability In both cases, "converge" means "the originator node has received
a response from the destination node".
The ability of the home network to support auto-configuration is of 3.8. Manageability
the utmost importance. Indeed, most end users will not have the
The ability of the home network to support auto-configuration is
of the utmost importance. Indeed, most end users will not have the
expertise and the skills to perform advanced configuration and expertise and the skills to perform advanced configuration and
troubleshooting. Thus the routing protocol designed for home PAN MUST troubleshooting. Thus the routing protocol designed for home
provide a set of features including zero-configuration of the routing automation networks MUST provide a set of features including zero-
protocol for a new node to be added to the network. From ROLL configuration of the routing protocol for a new node to be added
perspective, zero-configuration means that a node can obtain an to the network. From a routing perspective, zero-configuration
address and join the network on its own, without human intervention. means that a node can obtain an address and join the network on
its own, without human intervention.
3.9. Stability
The routing protocol MUST support the ability to isolate a The routing protocol MUST support the ability to isolate a
misbehaving node thus preserving the correct operation of overall misbehaving node thus preserving the correct operation of the
network. overall network.
5. Traffic Pattern 4. Traffic Pattern
Depending on the philosophy of the home network, wall switches may be Depending on the design philosophy of the home network, wall
configured to directly control individual lamps or alternatively, all switches may be configured to directly control individual lamps or
wall switches send control commands to a central lighting control alternatively, all wall switches send control commands to a
computer which again sends out control commands to relevant devices. central lighting control computer which again sends out control
commands to relevant devices.
In a distributed system, the traffic tends to be any-to-many. In a In a distributed system, the traffic tends to be multipoint-to-
centralized system, it is a mix of any-to-one and one-to-many. multipoint. In a centralized system, it is a mix of multipoint-to-
point and point-to-multipoint.
Wall switches only generate traffic when activated, which typically Wall switches only generate traffic when activated, which
happens from a one to tens of times per hour. typically happens from a one to tens of times per hour.
Remote controls have a similar transmit pattern to wall switches, but Remote controls have a similar transmit pattern to wall switches,
are activated more frequently. but are activated more frequently.
Temperature/air pressure/rain sensors send frames when queried by the Temperature/air pressure/rain sensors send frames when queried by
user or can be preconfigured to send measurements at fixed intervals the user or can be preconfigured to send measurements at fixed
(typically minutes). Motion sensors typically send a frame when intervals (typically minutes). Motion sensors typically send a
motion is first detected and another frame when an idle period with frame when motion is first detected and another frame when an idle
no movement has elapsed. The highest transmission frequency depends period with no movement has elapsed. The highest transmission
on the idle period used in the sensor. Sometimes, a timer will frequency depends on the idle period used in the sensor.
trigger a frame transmission when an extended period without status Sometimes, a timer will trigger a frame transmission when an
change has elapsed. extended period without status change has elapsed.
All frames sent in the above examples are quite short, typically less All frames sent in the above examples are quite short, typically
than 5 bytes of payload. Lost frames and interference from other less than 5 bytes of payload. Lost frames and interference from
transmitters may lead to retransmissions. In all cases, other transmitters may lead to retransmissions. In all cases,
acknowledgment frames with a size of a few bytes are used. acknowledgment frames with a size of a few bytes are used.
6. Open issues 5. Open Issues
Other items to be addressed in further revisions of this document Other items to be addressed in further revisions of this document
include: include:
o Load Balancing (Symmetrical and Asymmetrical) o Load Balancing (Symmetrical and Asymmetrical)
o Groupcast definition in a separate document? (TBD)
o Use case: Home Control Installer Scenario
o Security o Security
7. Security Considerations 6. Security Considerations
Encryption can be employed to provide confidentiality, integrity and
authentication of the messages carried on the wireless links. Adding
these capabilities to the ROLL devices will degrade energy efficiency
and increase cost, so a trade-off must be made for each specific
application.
Door locks, alarm sensors and medication dosage equipment are Implementing security mechanisms in ROLL network devices may
examples where strong encryption and authentication are needed. The degrade energy efficiency and increase cost.
command to unlock a door must be authenticated, as must the
communication between an alarm sensor and the central alarm
controller. Furthermore, traffic analysis of the alarm system
communication must not reveal if the alarm is activated.
Light dimmers, window shades, motion sensors, weight sensors etc. may The routing protocol chosen for ROLL MUST allow for low-power,
not need encryption. low-cost network devices with limited security needs.
Protection against unintentional inclusion in neighboring networks Protection against unintentional inclusion in neighboring networks
must be provided. Providing confidentiality, integrity and MUST be provided.
authentication against malicious opponents is optional.
8. IANA Considerations 7. IANA Considerations
This document includes no request to IANA. This document includes no request to IANA.
9. Acknowledgments 8. Acknowledgments
J. P. Vasseur, Jonathan Hui, Eunsook "Eunah" Kim, Mischa Dohler and J. P. Vasseur, Jonathan Hui, Eunsook "Eunah" Kim, Mischa Dohler
Massimo Maggiorotti are gratefully acknowledged for their and Massimo Maggiorotti are gratefully acknowledged for their
contributions to this document. contributions to this document.
This document was prepared using 2-Word-v2.0.template.dot. This document was prepared using 2-Word-v2.0.template.dot.
10. References 9. References
10.1. Normative References As an exception, this internet draft contains references to other
internet drafts. The reason is that the referenced internet drafts
are developed in parallel to this document.
When promoted to an RFC, the references MUST be updated to RFCs as
well or removed from the references section.
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
10.2. Informative References draft-ietf-roll-indus-routing-reqs-01.txt
draft-ietf-roll-urban-routing-reqs-01.txt
draft-martocci-roll-commercial-routing-reqs-00.txt
draft-ietf-roll-protocols-survey-00.txt
9.2. Informative References
Author's Addresses Author's Addresses
Anders Brandt Anders Brandt
Zensys, Inc. Zensys, Inc.
Emdrupvej 26 Emdrupvej 26
Copenhagen, DK-2100 Copenhagen, DK-2100
Denmark Denmark
Email: abr@zen-sys.com Email: abr@zen-sys.com
Jakob Buron
Zensys, Inc.
Emdrupvej 26
Copenhagen, DK-2100
Denmark
Email: jbu@zen-sys.com
Giorgio Porcu Giorgio Porcu
Telecom Italia Telecom Italia
Piazza degli Affari, 2 Piazza degli Affari, 2
20123 Milan 20123 Milan
Italy Italy
Email: giorgio.porcu@guest.telecomitalia.it Email: giorgio.porcu@guest.telecomitalia.it
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