Networking Working Group J. Martocci, Ed.
Internet-Draft Johnson Controls Inc.
Intended status: Informational Pieter De Mil
Expires: March 3, 2009 Ghent University - IBCN
W. Vermeylen
Arts Centre Vooruit
September 3, 2008
Commercial Routing Requirements in Low Power and Lossy Networks
draft-martocci-roll-building-routing-reqs-00
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Abstract
The ROLL Working Group was recently chartered by the IETF to define
routing characteristics for low power embedded devices. ROLL would
like to serve the Industrial, Commercial (Building), Home and Urban
markets. Pursuant to this effort, this document defines the
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functional requirements for installing integrated facility management
systems in commercial facilities. The body of this document defines
the routing requirements for commercial building application. Other
commercial building requirements such as cost and installation
requirements have been included in Appendix A for reference.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 Error!
Reference source not found..
Table of Contents
1. Terminology....................................................4
2. Introduction...................................................7
2.1. FMS Topology..............................................8
2.1.1. Introduction.........................................8
2.1.2. Sensors/Actuators....................................9
2.1.3. Area Controllers.....................................9
2.1.4. Zone Controllers.....................................9
2.2. Installation Methods.....................................10
2.2.1. Wired Communication Media...........................10
2.2.2. Device Density......................................10
3. Building Automation Applications..............................12
3.1. Locking and Unlocking the Building.......................12
3.2. Building Energy Conservation.............................13
3.3. Inventory and Remote Diagnosis of Safety Equipment.......13
3.4. Life Cycle of Smoke Detectors............................13
3.5. Surveillance.............................................14
3.6. Emergency................................................14
3.7. Public Address...........................................14
3.8. Positioning..............................................14
4. Building Automation Routing Requirements......................15
4.1. Installation.............................................15
4.1.1. Computer-free installation..........................15
4.1.2. Fixed addressing....................................15
4.1.3. Network Setup Time..................................16
4.1.4. Battery Powered devices.............................16
4.1.5. Local Testing.......................................16
4.2. Scalability..............................................16
4.2.1. Network Domain......................................16
4.2.2. Communication Distance..............................16
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4.2.3. Automatic Gain Control..............................17
4.2.4. Peer-to-peer Communication..........................17
4.3. Mobility.................................................17
4.3.1. Mobile Device Association...........................17
4.4. Resource Constrained Devices.............................17
4.4.1. Cost................................................17
4.4.2. Limited Processing Power Sensors/Actuators..........18
4.4.3. Limited Processing Power Controllers................18
4.4.4. Parenting for Constrained Devices...................18
4.4.5. Adjustable System Table Sizes.......................18
4.5. Prioritized Routing......................................18
4.5.1. QoS.................................................18
4.6. Addressing...............................................19
4.6.1. Unicast/Multicast/Anycast...........................19
4.6.2. Unique Addresses....................................19
4.7. Manageability............................................19
4.7.1. Device Replacement..................................19
4.7.2. Firmware Upgrades...................................19
4.7.3. Diagnostics.........................................20
4.7.4. Trace Route.........................................20
4.8. Compatibility............................................20
4.8.1. IPv4 Compatibility..................................20
4.8.2. Maximum Packet Size.................................20
4.9. Route Selection..........................................20
4.9.1. Path Cost...........................................21
4.9.2. Path Adaptation.....................................21
4.9.3. Route Redundancy....................................21
4.9.4. Route Preference....................................21
4.9.5. Path Symmetry.......................................21
4.9.6. Path Persistence....................................21
4.10. Reliability.............................................22
4.10.1. Device Integrity...................................22
5. Traffic Pattern...............................................22
6. Open issues...................................................22
7. Security Considerations.......................................23
8. IANA Considerations...........................................23
9. Acknowledgments...............................................23
10. References...................................................23
10.1. Normative References....................................23
10.2. Informative References..................................24
Disclaimer of Validity...........................................25
11. APPENDIX A - Additional Building Requirements (Informative)..26
11.1. Additional Commercial Product Requirements..............26
11.1.1. Wired and Wireless Imlementations..................26
11.1.2. World-wide Applicability...........................26
11.1.3. Support of Building Protocol - BACnet..............27
11.1.4. Support of Building Protocol - LON.................27
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11.1.5. Energy Harvested Sensors...........................27
11.2. Additional Installation and Commissioning Requirements..27
11.2.1. Device Setup Time..................................27
11.2.2. Unavailability of an IT network....................27
11.3. Additional Network Requirements.........................27
11.3.1. TCP/UDP............................................27
11.3.2. Data Rate Performance..............................27
11.3.3. Interference Mitigation............................28
11.3.4. Real-time Performance Measures.....................28
11.3.5. Packet Reliability.................................28
1. Terminology
Access Point: The access point is an infrastructure device that
connects the low power and lossy network system to the
Internet, possibly via a customer premises local area
network (LAN).
Actuator: A field device that controls and/or modulates a flow
of a gas or liquid; or controls electricity
distribution.
ASHRAE: American Society of Heating, Refrigerating and Air-
Conditioning Engineers
BAS: Building Automation System. This term is synonymous
with Facility Management System (FMS).
BMS: Building Automation System. This term is synonymous
with Facility Management System (FMS).
Channel: Radio frequency sub-band used to transmit a modulated
signal carrying packets.
Channel Hopping An algorithm by which field devices synchronously
change channels during operation
Commissioning Tool: Any physical or logical device temporarily added
to the network for the expressed purpose of setting up
the network and device operational parameters.
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Controller: A field device that can receive sensor input and
automatically change the environment in the facility
by manipulating digital or analog actuators.
Downstream: Data direction traveling from a Local Area Network
(LAN) to a Personal Area Network (PAN) device.
Field Device: Physical devices placed in the plant's operating
environment (both RF and environmental). Field
devices include sensors and actuators as well as
network routing devices and access points
Fire: The term used to describe building equipment used to
monitor, control and evacuate an internal space in
case of a fire situation. Equipment includes smoke
detectors, pull boxes, sprinkler systems and
evacuation control.
FFD: Full Function Device. An 802.15.4 device that can
route messages across the mesh in addition to
providing an end application. Most FFD are line
powered since they must always be ready to forward
messages.
FMS: Facility Management System. A global term applied
across all the vertical designations within a building
including, HVAC, Fire, Security, Lighting and Elevator
control.
HVAC: Heating, Ventilation and Air Conditioning. A term
applied to the comfort level of an internal space.
IETF: Internet Engineering Task Force
Intrusion Protection: A term used to protect resources from
external infiltration. Intrusion protection systems
utilize door locks, window tampers and card readers.
LAN: Local Area Network.
PAN: Personal Area Network.
A geographically limited wireless network based on
e.g. 802.15.4 or Z-Wave radio.
ROLL: Routing Over Low-power and Lossy networks
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ROLL device: A ROLL network node with constrained CPU and memory
resources; potentially constrained power resources.
Sensor: A PAN device that measures data and/or detects an
event.
Upstream: Data direction traveling from a PAN to a LAN device.
LLN: Low power and Lossy networks (LLNs) are typically
composed of many embedded devices with limited power,
memory, and processing resources interconnected by a
variety of links, such as IEEE 802.15.4, Bluetooth,
Low Power WiFi
Lighting: The term used to describe building equipment used to
monitor and control an internal or external lighted
space. Equipment includes occupancy sensors, light
switches and ballasts.
LLN: Low power and Lossy Network.
PAN: Personnel Area Network
RF: Radio Frequency
RFD: Reduced Function Device. An 802.15.4 device that can
send messages on the network; receive messages from
the network; but cannot route messages across the
network. In most cases these devices are edge devices
of the network.. RFDs may be line powered, but also
can be battery powered since they play no role on the
mesh.
ROLL: Routing over Low power and Lossy networks. This IETF
working group will develop routing characteristics and
rules for supporting LLNs utilizing 6LoWPAN.
Security: The term used to describe building equipment used to
monitor and control occupant and equipment safety
inside a building. Equipment includes window tamper
switches, door access systems, infrared detection
systems, and video cameras.
Sensors: A field device that monitors an environmental
condition in a building and reports its findings to
higher order devices for control and alarming
operations.
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Superframe: A collection of timeslots repeating at a constant
rate.
TC: Trust Center. A logical device on the network that is
trusted by the network members. The TC administers
security policy.
Timeslot: A fixed time interval that may be used for the
transmission or reception of a packet between two
field devices. A timeslot used for communications is
associated with a slotted-link
Upstream: Data direction travelling from the field device to the
host application.
2. Introduction
Commercial buildings have been fitted with pneumatic and subsequently
electronic communication pathways connecting sensors to their
controllers for over one hundred years. Recent economic and
technical advances in wireless communication allow facilities to
increasingly utilize a wireless solution in lieu of a wired solution;
thereby reducing installation costs while maintaining highly reliant
communication. Wireless solutions will be adapted from their
existing wired counterparts in many of the building applications
including, but not limited to HVAC, Lighting, Physical Security,
Fire, and Elevator systems. These devices will be developed to
reduce installation costs; while increasing installation and retrofit
flexibility. Sensing devices may be battery or mains powered.
Actuators and area controllers will be mains powered.
Facility Management Systems (FMS) are deployed in a large set of
vertical markets including universities; hospitals; government
facilities; K-12; pharmaceutical manufacturing facilities; and
single-tenant or multi-tenant office buildings. These buildings range
in size from 100K sqft structures (5 story office buildings), to 1M
sqft skyscrapers (100 story skyscrapers) to complex government
facilities such as the Pentagon. The described topology is meant to
be the model to be used in all these types of environments, but
clearly must be tailored to the building class, building tenant and
vertical market being served.
The following sections describe the sensor, actuator, area controller
and zone controller layers of the topology. (NOTE: The Building
Controller and Enterprise layers of the FMS are excluded from this
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discussion since they typically deal in communication rates requiring
WLAN communication technologies. Each section describes the basic
functionality of the layer, its networking model, power requirements
and a brief description of the communication requirements.
2.1. FMS Topology
2.1.1. Introduction
To understand the network systems requirements of a facility
management system in a commercial building, this document uses a
framework to describe the basic functions and composition of the
system. An FMS is a horizontally layered system of sensors,
actuators, controllers and user interface devices. Additionally, an
FMS may also be divided vertically across alike, but different
building subsystems such as HVAC, Fire, Security, Lighting, Shutters
and Elevator control systems as denoted in Figure 1.
Much of the makeup of an FMS is optional and installed at the behest
of the customer. Sensors and actuators have no standalone
functionality. All other devices support partial or complete
standalone functionality. These devices can optionally be tethered
to form a more cohesive system. The customer requirements dictate
the level of integration within the facility. This architecture
provides excellent fault tolerance since each node is designed to
operate in an independent mode if the higher layers are unavailable.
+------+ +-----+ +------+ +------+ +------+ +------+
Bldg App'ns | | | | | | | | | | | |
| | | | | | | | | | | |
Building Cntl | | | | | S | | L | | S | | E |
| | | | | E | | I | | H | | L |
Area Control | H | | F | | C | | G | | U | | E |
| V | | I | | U | | H | | T | | V |
Zone Control | A | | R | | R | | T | | T | | A |
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| C | | E | | I | | I | | E | | T |
Actuators | | | | | T | | N | | R | | O |
| | | | | Y | | G | | S | | R |
Sensors | | | | | | | | | | | |
+------+ +-----+ +------+ +------+ +------+ +------+
Figure 1 - Building Systems and Devices
2.1.2. Sensors/Actuators
As Figure 1 indicates an FMS may be composed of many functional
stacks or silos that are interoperably woven together via Building
Applications. Each silo has an array of sensors that monitor the
environment and actuators that effect the environment as determined
by the upper layers of the FMS topology. The sensors typically are
the leaves of the network tree structure providing environmental data
into the system. The actuators are the sensors counterparts
modifying the characteristics of the system based on the input sensor
data and the applications deployed.
2.1.3. Area Controllers
An area describes a small physical locale within a building,
typically a room. As noted in Figure 1 the HVAC, Security and
Lighting functions within a building address area or room level
applications. Area controls are fed by sensor inputs that monitor
the environmental conditions within the room. Common sensors found
in many rooms that feed the area controllers include temperature,
occupancy, lighting load, solar load and relative humidity. Sensors
found in specialized rooms (such as chemistry labs) might include air
flow, pressure, CO2 and CO particle sensors. Room actuation includes
temperature setpoint, lights and blinds/curtains.
2.1.4. Zone Controllers
Zone Control supports a similar set of characteristics as the Area
Control albeit to an extended space. A zone is normally a logical
grouping or functional division of a commercial building. A zone may
also coincidentally map to a physical locale such as a floor.
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Zone Control may have direct sensor inputs (smoke detectors for
fire), controller inputs (room controllers for air-handlers in HVAC)
or both (door controllers and tamper sensors for security). Like
area/room controllers, zone controllers are standalone devices that
operate independently or may be attached to the larger network for
more synergistic control.
2.2. Installation Methods
2.2.1. Wired Communication Media
Commercial controllers are traditionally deployed in a facility using
twisted pair serial media following the EIA 485 electrical standard
operating nominally at 38400 to 76800 baud. This allows runs to 5000
ft without a repeater. With the maximum of three repeaters, a single
communication trunk can serpentine 15000 ft.
Most sensors and virtually all actuators currently used in commercial
buildings are "dumb", non-communicating hardwired devices. However,
sensor buses are beginning to be deployed by vendors which are used
for smart sensors and point multiplexing. The Fire industry deploys
addressable fire devices, which usually use some form of proprietary
communication wiring driven by fire codes.
2.2.2. Device Density
Device density differs depending on the application and code
requirements. The following sections detail typical installation
densities for different applications.
2.2.2.1. HVAC Device Density
HVAC room applications typically have sensors and controllers spaced
about 50ft apart. In most cases there is a 3:1 ratio of sensors to
controllers. That is, for each room there is an installed
temperature sensor, flow sensor and damper controller for the
associated room controller.
HVAC equipment room applications are quite different. An air handler
system may have a single controller with upwards to 25 sensors and
actuators within 50 ft of the air handler. A chiller or boiler is
also controlled with a single equipment controller instrumented with
25 sensors and actuators. Each of these devices would be
individually addressed. Air handlers typically serve one or two
floors of the building. Chillers and boilers may be installed per
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floor, but many times service a wing, building or the entire complex
via a central plant.
These numbers are typical. In special cases, such as clean rooms,
operating rooms, pharmaceuticals and labs, the ratio of sensors to
controllers can increase by a factor of three. Tenant installations
such as malls would opt for packaged units where much of the sensing
and actuation is integrated into the unit. Here a single device
address would serve the entire unit.
2.2.2.2. Fire Device Density
Fire systems are much more uniformly installed with smoke detectors
installed about every 50 feet. This is dictated by local building
codes. Fire pull boxes are installed uniformly about every 150 feet.
A fire controller will service a floor or wing. The fireman's fire
panel will service the entire building and typically is installed in
the atrium.
2.2.2.3. Lighting Device Density
Lighting is also very uniformly installed with ballasts installed
approximately every 10 feet. A lighting panel typically serves 48 to
64 zones. Wired systems typically tether many lights together into a
single zone. Wireless systems configure each fixture independently
to increase flexibility and reduce installation costs.
2.2.2.4. Physical Security Device Density
Security systems are non-uniformly oriented with heavy density near
doors and windows and lighter density in the building interior space.
The recent influx of interior and perimeter camera systems is
increasing the security footprint. These cameras are atypical
endpoints requiring upwards to 1mbps data rates per camera as
contrasted by the few kbps needed by most other FMS sensing
equipment. To date, camera systems have been deployed on a
proprietary wired high speed network or on enterprise VLAN. Camera
compression technology now supports full-frame video over wireless
media.
2.2.2.5. Installation Procedure
Wired FMS installation is a multifaceted procedure depending on the
extent of the system and the software interoperability requirement.
However, at the sensor/actuator and controller level, the procedure
is typically a two or three step process.
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Most FMS equipment is 24 VAC equipment that can be installed by a
low-voltage electrician. He/she arrives on-site during the
construction of the building prior to the sheet wall and ceiling
installation. This allows him/her to allocate wall space, easily
land the equipment and run the wired controller and sensor networks.
The Building Controllers and Enterprise network are not normally
installed until months later. The electrician completes his task by
running a wire verification procedure that shows proper continuity
between the devices and proper local operation of the devices.
Later in the installation cycle, the higher order controllers are
installed, programmed and commissioned together with the previously
installed sensors, actuators and controllers. In most cases the IP
network is still not operable. The Building Controllers are
completely commissioned using a crossover cable or a temporary IP
switch together with static IP addresses.
Once the IP network is operational, the FMS may optionally be added
to the enterprise network. Wireless installation will necessarily
need to keep the same work flow. The electrician will install the
products as before and run continuity tests between the wireless
devices to assure operation before leaving the job. The electrician
does not carry a laptop so the commissioning must be built into the
device operation.
3. Building Automation Applications
Vooruit is an arts centre in a restored monument which dates from
1913. This complex monument consists of 366 different rooms
including a concert hall, theater hall, several bars, etc. About
2000 activities take place at Vooruit on a yearly basis, some
activities simultaneously with a total maximum of 3500 visitors. A
number of use cases regarding Vooruit are described in the following
text. The situations and needs described in these use cases can also
be found in all automated large buildings, such as airports and
hospitals.
3.1. Locking and Unlocking the Building
The member of the cleaning staff arrives first in the morning
unlocking the building (or a part of it) from the control room. This
means that several doors are unlocked; the alarms are switched off;
the heating turns on; some lights switch on, etc. Similarly, the
last person leaving the building has to lock the building. This will
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lock all the outer doors, turn the alarms on, switch off heating and
lights, etc.
This use case is also useful in the home automation scenario,
although the requirement about preventing the "popcorn effect" [REF
HOME AUTOMATION] can be relaxed a little bit in building automation.
It would be nice if lights, roll-down shutters and other actuators in
the same room or areas with transparent walls execute the command
around the same time (a tolerance of 200 ms is allowed).
3.2. Building Energy Conservation
A room that is not in use should not be heated, air conditioned or
ventilated and the lighting should be turned off. In a building with
366 rooms it can happen quite frequently that someone forgets to
switch off the HVAC and lighting. This is a real waste of valuable
energy. To prevent this from happening, the janitor can program the
building according to the day's schedule. This way lighting and HVAC
is turned on prior to the use of a room, and turned off afterwards.
Using such a system Vooruit has realized a saving of 35% on the gas
and electricity bills. Making the control of the building management
system wireless (e.g. over a PDA) would be an advantage as you do not
have to cross the complete building to the control room to change the
temperature of a single room.
3.3. Inventory and Remote Diagnosis of Safety Equipment
Each month Vooruit is obliged to make an inventory of its safety
equipment. This task takes two working days. Each fire extinguisher
(100), fire blanket (10), fire-resisted door (120) and evacuation
plan (80) must be checked for presence and proper operation. Also
the battery and lamp of every safety lamp must be checked before each
public event (safety laws). Automating this process would heavily
cut into working hours.
3.4. Life Cycle of Smoke Detectors
A smoke detector must be replaced periodically. A secure mechanism
is needed to remove the old device and install the new device.
During construction work, the safety can be augmented by temporarily
adding extra sensing and/or actuating devices.
This life cycle management use case is valid for each type of device
we wish to add or to replace. What is the maximum of the time we
allow for each task (adding a new device, removal of a device,
replacement of a device)? The negative impact on the functionality
of the network should be minimal.
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3.5. Surveillance
To protect the building against burglary a guard must be able to
monitor and control all entrances (open/close, latch moved) and
lights (activated outside the opening hours). It should also be
possible to view video streams from several security cameras either
from the control room or on a PDA of an in-the-field security person.
The arriving and exiting visitors also must be monitored from the
control room to guarantee their security.
3.6. Emergency
In case of an emergency it is very important that all the visitors be
evacuated as quickly as possible. The fire and smoke detectors have
to set off an alarm, and alert the mobile personnel on their internal
mobile telephone system and/or PDAs. All emergency exits have to be
instantly unlocked and the emergency lighting has to guide the
visitors to these exits. The necessary sprinklers have to be
activated and the electricity grid has to be monitored and if it
becomes necessary to shut down some parts of the building. Emergency
services have to be notified instantly. A wireless system could
bring in some extra safety features. Locating fire fighters and
guiding them through the building could be a life-saving application.
This is also the case for wireless camera surveillance which is
monitored via PDA.
3.7. Public Address
It should be possible to send video, audio and text messages to the
visitors in the building. These messages can be very diverse, e.g.
commercials on televisions in the bar, ASCII text boards displaying
the name of the event in a room, video screens with an outline of the
upcoming events at Vooruit, audio announcements such as delays in the
program, lost and found children, evacuation orders, etc.
3.8. Positioning
Person localization / equipment theft: 2s - room accuracy required -
high responsiveness required to cope with movement Interaction
positioning: detect vicinity of two nodes (people or equipment): 1s -
sub-room accuracy - high responsiveness required to cope with
movement Equipment localization: 2-4s Or Asset Management - room
accuracy required - medium responsiveness.
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4. Building Automation Routing Requirements
Following are the building automation routing requirements for a
network used to integrate building sensor actuator and control
products. These requirements have been limited to 'routing'
requirements only. These requirements are written not presuming any
preordained network topology, physical media (wired) or radio
technology (wireless). See Appendix A for additional requirements
that have been deemed outside the scope of this document yet will
pertain to the successful deployment of building automation systems.
4.1. Installation
Building control systems typically are installed and tested by
electricians having little computer knowledge and no network
knowledge whatsoever. These systems are often installed during the
building construction phase before the drywall and ceilings are in
place. There is never an IP network in place during this
installation.
In retrofit applications, pulling wires from sensors to controllers
can be costly and in some applications (e.g. museums) not feasible.
Local testing of sensors and room controllers must be completed
before the tradesperson can complete his/her work. System level
commissioning will later be deployed using a more computer savvy
person with access to a laptop computer. The completely installed
and commissioned IP network may or may not be in place at this time.
Following are the installation routing requirements.
4.1.1. Computer-free installation
It MUST be possible to fully commission devices without requiring any
additional commissioning device (e.g. laptop). The device MAY be
completely configured for network operation by setting a bank of
switches. The number of switches MUST not exceed 16 switches.
4.1.2. Fixed addressing
The device network address MUST be settable and henceforth fixed for
the device without the need for other system devices such as DHCP
servers.
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4.1.3. Network Setup Time
Network setup MUST support device commissioning times of no more than
15 minutes per sensor/controller pair.
4.1.4. Battery Powered devices
Sensing devices must be able to utilize battery power yet still be
viable devices on a ROLL network. Batteries must be operational for
at least 5 years when the sensing device is transmitting its data (64
bytes) once per minute.
4.1.5. Local Testing
The local sensors and requisite actuators and controllers must be
testable within the locale (e.g. room) to assure communication
connectivity and local operation.
4.2. Scalability
Building control systems are designed for facilities from 50000 sq.
ft. to 1M+ sq. ft. The networks that support these systems must
cost-effectively scale accordingly. In larger facilities
installation may occur simultaneously on various wings or floors, yet
the end system must seamlessly merge. Following are the scalability
requirements.
4.2.1. Network Domain
A network MUST operationally support at least 1000 routing and 1000
non-routing devices.
Subnetworks (e.g. rooms, primary equipment) within the network must
support upwards to 255 sensors and/or actuators.
Subnetworks MUST seamlessly merge into networks. Networks MUST
seamlessly merge into internetworks.
4.2.2. Communication Distance
A source device may be upwards to 1000 feet from its destination.
Communication MUST be established between these devices without
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needing to install other intermediate 'communication only' devices
such as repeaters.
4.2.3. Automatic Gain Control
For wireless implementations, the routing algorithms SHOULD
incorporate automatic transmit power regulation to maximize packet
transfer and minimize network interference regardless of network size
or density.
4.2.4. Peer-to-peer Communication
Network devices MUST be able to communicate in a peer-to-peer manner
with all other devices on the network without being subject to
intermediate bridge or gating devices.
4.3. Mobility
Most devices are affixed to walls or installed on ceilings within
buildings. Hence the mobility requirements for commercial buildings
are few. However, in wireless environments location tracking of
occupants and assets is gaining favor.
4.3.1. Mobile Device Association
Mobile devices SHOULD be capable of unjoining from an old network
joining onto a new network within 15 seconds.
4.4. Resource Constrained Devices
Sensing and actuator device processing power and memory may be 4
orders of magnitude less (i.e. 10,000x) than many more traditional
client devices on an IP network. The routing algorithms must
therefore be tailored to fit these resource constrained devices.
4.4.1. Cost
The total installed infrastructure cost including but not limited to
the media, required infrastructure devices (amortized across the
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number of devices); labor to install and commission the network MUST
not exceed $1.00/foot for wired implementations.
Wireless implementations (total installed cost) must cost no more
than 80% of wired implementations.
4.4.2. Limited Processing Power Sensors/Actuators
The software stack requirements for sensors and actuators MUST be
implementable in 8-bit devices with no more than 128kb of flash
memory (including at least 32Kb for the application code) and no more
than 8Kb of RAM (including at least 1Kb RAM available for
application).
4.4.3. Limited Processing Power Controllers
The software stack requirements for room controllers SHOULD be
implementable in 8-bit devices with no more than 256kb of flash
memory (including at least 32Kb for the application code) and no more
than 8Kb of RAM (including at least 1Kb RAM available for
application)
4.4.4. Parenting for Constrained Devices
The routing algorithms must support in-bound packet caches for sensor
and actuator devices when these devices are not accessible on the
network. The cached packets need to be delivered to its destination
when the device is accessible on the network.
4.4.5. Adjustable System Table Sizes
ROLL routing MUST support adjustable router table entry sizes on a
per node basis to maximize limited RAM in the devices.
4.5. Prioritized Routing
Network and application routing prioritization is required to assure
that mission critical applications (e.g. Fire Detection) cannot be
deferred while less critical application access the network.
4.5.1. QoS
Routers MUST support quality of service prioritization to assure
timely response for critical FMS packets (e.g. Fire and Security
events).
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4.6. Addressing
Facility Management systems require different communication schema to
solicit or post network information. Broadcasts or anycasts need be
used to resolve unresolved references within a device when the device
first joins the network. Devices operating within a specified locale
such as a room will need to multicast to all devices within the room.
4.6.1. Unicast/Multicast/Anycast
Routing MUST support anycast, unicast, multicast and broadcast
services (or IPv6 equivalent).
4.6.2. Unique Addresses
Sensor/Actuator/Controller addressability MUST be unique site-wide.
All addressable nodes MUST be accessible to all other nodes in the
internetwork.
4.7. Manageability
In addition to the initial installation of the system (see Section
4.1), the ongoing maintenance of the system is equally important to
be simple and inexpensive.
4.7.1. Device Replacement
Replacement devices must be plug-n-play with no additional setup than
what is normally required for a new device. No bound information
from other nodes MUST need be reconfigured.
4.7.2. Firmware Upgrades
To support high speed code downloads, a mechanism MUST be defined to
download firmware to devices in parallel yet support guaranteed
delivery. Devices receiving a high speed download MAY cease normal
operation, but upon completion of the download MUST automatically
resume normal operation.
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4.7.3. Diagnostics
To improve diagnostics, the network layer SHOULD be able to be placed
in and out of 'verbose' mode. Verbose mode is a temporary debugging
mode that provides additional communication information including at
least total number of packets sent, packets received, number of
failed communication attempts, neighbor table and routing table
entries.
4.7.4. Trace Route
Network diagnostics such as PING and Trace Route SHOULD be supported
with extensions in Trace Route describing wireless parameter
information when applicable.
4.8. Compatibility
The building automation industry adheres to application layer
protocol standards to achieve vendor interoperability. These
standards are BACnet and LON. It is estimated that fully 80% of the
customer bid requests received world-wide will require compliance to
one or both of these standards. The ROLL routing algorithms will
therefore need to dovetail to these application protocols to assure
acceptance in the building automation industry. These protocols have
been in place for over 10 years. Many sites will require backwards
compatibility with the existing legacy devices.
4.8.1. IPv4 Compatibility
The routing protocol MUST define a communication scheme to assure
compatibility of IPv4 and IPv6 devices.
4.8.2. Maximum Packet Size
Routing algorithms must support packet sizes to 1526 octets.
4.9. Route Selection
Route selection determines reliability and quality of the
communication paths among the devices. Optimizing the routes over
time resolve any nuances developed at system startup when nodes are
asynchronously adding themselves to the network. Route adaptation
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also reduces latency if the new route costs consider hop count as a
cost attribute.
4.9.1. Path Cost
Path selection MUST be based on path quality, rather than signal
strength only. Path quality includes signal strength, available
bandwidth, hop count and communication error rates.
4.9.2. Path Adaptation
Communication paths MUST adapt toward signal quality optimality in
time.
4.9.3. Route Redundancy
To reduce real-time latency, the network layer SHOULD be configurable
to allow secondary and tertiary paths to be established and used upon
failure of the primary path
4.9.4. Route Preference
The route discovery mechanism SHOULD allow a source node (sensor) to
dictate a configured destination node (controller) as a preferred
routing path.
4.9.5. Path Symmetry
The network layer SHOULD support both asymmetric and symmetric routes
as requested by the application layer. When the application layer
selects asymmetry the network layer MAY elect to find either
asymmetric or symmetric routes. When the application layer requests
symmetric routes, then only symmetric routes MUST be utilized. The
default MUST be asymmetric routes.
4.9.6. Path Persistence
Devices SHOULD optionally persist communication paths across boots
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4.10. Reliability
4.10.1. Device Integrity
Commercial Building devices MUST all be periodically scanned to
assure that the device is viable and can communicate data and alarm
information as needed.
5. Traffic Pattern
The independent nature of the automation systems within a building
plays heavy onto the network traffic patterns. Much of the real-time
sensor data stays within the local environment. Alarming and other
event data will percolate to higher layers.
Systemic data may be either polled or event based. Polled data
systems will generate a uniform packet load on the network. This
architecture has proven not scalable. Most vendors have developed
event based systems which passes data on event. These systems are
highly scalable and generate low data on the network at quiescence.
Unfortunately, the systems will generate a heavy load on startup
since all the initial data must migrate to the controller level.
They also will generate a temporary but heavy load during firmware
upgrades. This latter load can normally be mitigated by performing
these downloads during off-peak hours.
Devices will need to reference peers occasionally for sensor data or
to coordinate across systems. Normally, though, data will migrate
from the sensor level upwards through the local, area then
supervisory level. Bottlenecks will typically form at the funnel
point from the area controllers to the supervisory controllers.
6. Open issues
Other items to be addressed in further revisions of this document
include:
Need to complete the Acknowledgement section below and develop
Reference and Normative Reference sections.
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7. Security Considerations
Security policies, especially wireless encryption and overall device
authentication need to be considered. These issues are out of scope
for the routing requirements, but could have an impact on the
processing capabilities of the sensors and controllers.
As noted above, the FMS systems are typically highly configurable in
the field and hence the security policy is most often dictated by the
type of building to which the FMS is being installed.
8. IANA Considerations
This document includes no request to IANA.
9. Acknowledgments
J. P. Vasseur, Ted Humpal and Zach Shelby are gratefully acknowledged
for their contributions to this document.
This document was prepared using 2-Word-v2.0.template.dot.
10. References
TBD
10.1. Normative References
TBD
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10.2. Informative References
Authors' Addresses
Jerry Martocci
Johnson Control
507 E. Michigan Street
Milwaukee, Wisconsin, 53202
USA
Phone: 414.524.4010
Email: jerald.p.martocci@jci.com
Nicolas Riou
?
?
?
Phone: ?
Email: nicolas.riou@fr.schneider-electric.com
Pieter De Mil
Ghent University - IBCN
G. Crommenlaan 8 bus 201
Ghent 9050
Belgium
Phone: +32-9331-4981
Fax: +32--9331--4899
Email: pieter.demil@intec.ugent.be
Wouter Vermeylen
Arts Centre Vooruit
???
Ghent 9000
Belgium
Phone: ???
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Fax: ???
Email: wouter@vooruit.be
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This document is subject to the rights, licenses and restrictions
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Funding for the RFC Editor function is currently provided by the
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11. APPENDIX A - Additional Building Requirements (Informative)
Appendix A contains additional building requirements that were deemed
out of scope for the routing document yet provided ancillary
informational substance to the reader. The requirements will need to
be addressed by ROLL or other WGs before adoption by the building
automation industrial will be considered.
11.1. Additional Commercial Product Requirements
11.1.1. Wired and Wireless Imlementations
Solutions MUST support both wired and wireless implementations.
11.1.2. World-wide Applicability
Wireless devices MUST be supportable at the 2.4Ghz ISM band Wireless
devices SHOULD be supportable at the 900 and 868 ISM bands as well.
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11.1.3. Support of Building Protocol - BACnet
Devices implementing the ROLL features MUST be able to support the
BACnet protocol.
11.1.4. Support of Building Protocol - LON
Devices implementing the ROLL features MUST be able to support the
LON protocol.
11.1.5. Energy Harvested Sensors
RFDs SHOULD target for operation using viable energy harvesting
techniques such as ambient light, mechanical action, solar load, air
pressure and differential temperature.
11.2. Additional Installation and Commissioning Requirements
11.2.1. Device Setup Time
Network setup by the installer MUST take no longer than 20 seconds
per device installed.
11.2.2. Unavailability of an IT network
Product commissioning MUST be performed by an application engineer
prior to the installation of the IT network.
11.3. Additional Network Requirements
11.3.1. TCP/UDP
Connection based and connectionless services MUST be supported
11.3.2. Data Rate Performance
An effective data rate of 20kbps is the lowest acceptable operational
data rate acceptable on the network.
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11.3.3. Interference Mitigation
The network MUST automatically detect interference and migrate the
network to a better 802.15.4 channel to improve communication.
Channel changes and nodes response to the channel change MUST occur
within 60 seconds.
11.3.4. Real-time Performance Measures
A node transmitting a 'request with expected reply' to another node
MUST send the message to the destination and receive the response
in not more than 120 msec. This response time SHOULD be achievable
with 5 or less hops in each direction.This requirement assumes
network quiescence and a negligible turnaround time at the
destination node.
11.3.5. Packet Reliability
Reliability MUST meet the following minimum criteria :
< 1% MAC layer errors on all messages; After no more than three
retries
< .1% Network layer errors on all messages;
After no more than three additional retries;
< 0.01% App?n layer errors on all messages.
Therefore application layer messages will fail no more than once
every 100,000 messages.
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