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Versions: (draft-martocci-roll-building-routing-reqs) 00 01 02 03 04 05 06 07 08 09 RFC 5867

Networking Working Group                                J. Martocci, Ed.
Internet-Draft                                     Johnson Controls Inc.
Intended status: Informational                            Pieter De Mil
Expires: August 3, 2009                           Ghent University IBCN
                                                           W. Vermeylen
                                                    Arts Centre Vooruit
                                                           Nicolas Riou
                                                     Schneider Electric
                                                        February 3, 2009


      Building Automation Routing Requirements in Low Power and Lossy
                                 Networks
                 draft-ietf-roll-building-routing-reqs-05


Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
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   This Internet-Draft will expire on August 3, 2009.

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   Copyright (c) 2009 IETF Trust and the persons identified as the
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Abstract

   The Routing Over Low power and Lossy network (ROLL) Working Group has
   been chartered to work on routing solutions for Low Power and Lossy
   networks (LLN) in various markets: Industrial, Commercial (Building),
   Home and Urban. Pursuant to this effort, this document defines the
   routing requirements for building automation.

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 [RFC2119].

Table of Contents

   1. Terminology....................................................4
   2. Introduction...................................................4
   3. Facility Management System (FMS) Topology......................5
      3.1. Introduction..............................................5
      3.2. Sensors/Actuators.........................................7
      3.3. Area Controllers..........................................7
      3.4. Zone Controllers..........................................7
   4. Installation Methods...........................................7
      4.1. Wired Communication Media.................................7
      4.2. Device Density............................................8
         4.2.1. HVAC Device Density..................................8
         4.2.2. Fire Device Density..................................9
         4.2.3. Lighting Device Density..............................9
         4.2.4. Physical Security Device Density.....................9
      4.3. Installation Procedure....................................9
   5. Building Automation Routing Requirements......................10
      5.1. Installation.............................................10
         5.1.1. Zero-Configuration Installation.....................11
         5.1.2. Sleeping Devices....................................11
         5.1.3. Local Testing.......................................11
         5.1.4. Device Replacement..................................12
      5.2. Scalability..............................................12
         5.2.1. Network Domain......................................12
         5.2.2. Peer-to-Peer Communication..........................12
      5.3. Mobility.................................................13
         5.3.1. Mobile Device Requirements..........................13
      5.4. Resource Constrained Devices.............................14
         5.4.1. Limited Processing Power for Non-routing Devices....14
         5.4.2. Limited Processing Power for Routing Devices........14
      5.5. Addressing...............................................14
         5.5.1. Unicast/Multicast/Anycast...........................14


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      5.6. Manageability............................................14
         5.6.1. Diagnostics.........................................15
         5.6.2. Route Tracking......................................15
      5.7. Route Selection..........................................15
         5.7.1. Path Cost...........................................15
         5.7.2. Path Adaptation.....................................15
         5.7.3. Route Redundancy....................................16
         5.7.4. Route Discovery Time................................16
         5.7.5. Route Preference....................................16
   6. Traffic Pattern...............................................16
   7. Security Considerations.......................................17
      7.1. Security Requirements....................................17
         7.1.1. Authentication......................................17
         7.1.2. Encryption..........................................18
         7.1.3. Disparate Security Policies.........................18
         7.1.4. Routing Security Policies To Sleeping Devices.......18
   8. IANA Considerations...........................................19
   9. Acknowledgments...............................................19
   10. References...................................................19
      10.1. Normative References....................................19
      10.2. Informative References..................................19
   11. Appendix A: Additional Building Requirements.................20
      11.1. Additional Commercial Product Requirements..............20
         11.1.1. Cost...............................................20
         11.1.2. Wired and Wireless Implementations.................20
         11.1.3. World-wide Applicability...........................20
         11.1.4. Support of Application Layer Protocols.............20
         11.1.5. Use of Constrained Devices.........................21
      11.2. Additional Installation and Commissioning Requirements..21
         11.2.1. Device Setup Time..................................21
         11.2.2. Unavailability of an IP network....................21
      11.3. Additional Network Requirements.........................21
         11.3.1. TCP/UDP............................................21
         11.3.2. Interference Mitigation............................21
         11.3.3. Real-time Performance Measures.....................21
         11.3.4. Packet Reliability.................................22
         11.3.5. Merging Commissioned Islands.......................22
         11.3.6. Adjustable System Table Sizes......................22
         11.3.7. Communication Distance.............................22
         11.3.8. Automatic Gain Control.............................22
         11.3.9. IPv4 Compatibility.................................23
         11.3.10. Proxying for Sleeping Devices.....................23
         11.3.11. Device and Network Integrity......................23
      11.4. Additional Performance Requirements.....................23
         11.4.1. Data Rate Performance..............................23
         11.4.2. Firmware Upgrades..................................23
         11.4.3. Prioritized Routing................................23


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         11.4.4. Path Persistence...................................24
      11.5. Additional Network Security Requirements................24
         11.5.1. Encryption Levels..................................24
         11.5.2. Security Policy Flexibility........................24
   12. Appendix B: FMS Use-Cases....................................24
      12.1. Locking and Unlocking the Building......................25
      12.2. Building Energy Conservation............................25
      12.3. Inventory and Remote Diagnosis of Safety Equipment......25
      12.4. Life Cycle of Field Devices.............................26
      12.5. Surveillance............................................26
      12.6. Emergency...............................................26
      12.7. Public Address..........................................27





1. Terminology

   For description of the terminology used in this specification, please
   see [I-D.ietf-roll-terminology].



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.

   The cost benefits and ease of installation of wireless sensors allow
   customers to further instrument their facilities with additional
   sensors; providing tighter control while yielding increased energy
   savings.

   Wireless solutions will be adapted from their existing wired
   counterparts in many of the building applications including, but not
   limited to Heating, Ventilation, and Air Conditioning (HVAC),
   Lighting, Physical Security, Fire, and Elevator systems. These
   devices will be developed to reduce installation costs; while
   increasing installation and retrofit flexibility, as well as
   increasing the sensing fidelity to improve efficiency and building
   service quality.


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   Sensing devices may be battery-less; battery or mains powered.
   Actuators and area controllers will be mains powered.  Due to
   building code and/or device density (e.g. equipment room), it is
   envisioned that a mix of wired and wireless sensors and actuators
   will be deployed within a building.

   Facility Management Systems (FMS) are deployed in a large set of
   vertical markets including universities; hospitals; government
   facilities; Kindergarten through High School (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
   discussion since they typically deal in communication rates requiring
   LAN/WLAN communication technologies).

   Section 3 describes FMS architectures commonly installed in
   commercial buildings.  Section 4 describes installation methods
   deployed for new and remodeled construction.  Appendix A documents
   important commercial building requirements that are out of scope for
   routing yet will be essential to the final acceptance of the
   protocols used within the building.  Appendix B describes various FMS
   use-cases and the interaction with humans for energy conservation and
   life-safety applications.

   Sections 3, 4, Appendix A and Appendix B are mainly included for
   educational purposes.  The aim of this document is to provide the set
   of IPv6 routing requirements for LLNs in buildings as described in
   Section 5.



3. Facility Management System (FMS) Topology

3.1. 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 hierarchical system of sensors, actuators,


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   controllers and user interface devices based on spatial extent.
   Additionally, an FMS may also be divided functionally 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   |

              |  C   | |  E  | |   I  | |   I  | |   E  | |  T   |

Actuators     |      | |     | |   T  | |   N  | |   R  | |  O   |

              |      | |     | |   Y  | |   G  | |   S  | |  R   |

Sensors       |      | |     | |      | |      | |      | |      |

              +------+ +-----+ +------+ +------+ +------+ +------+

                  Figure 1: Building Systems and Devices





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3.2. 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 fringe of the network structure providing environmental data into
   the system.  The actuators are the sensor's counterparts modifying
   the characteristics of the system based on the input sensor data and
   the applications deployed.

3.3. Area Controllers

   An area describes a small physical locale within a building,
   typically a room.  HVAC (temperature and humidity) and Lighting (room
   lighting, shades, solar loads) vendors oft times deploy area
   controllers. 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.

3.4. 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.

   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.



4. Installation Methods

4.1. Wired Communication Media

   Commercial controllers are traditionally deployed in a facility using
   twisted pair serial media following the EIA-485 electrical standard


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   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.  EIA-485 is a multi-drop
   media allowing upwards to 255 devices to be connected to a single
   trunk.

    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.

4.2. Device Density

   Device density differs depending on the application and as dictated
   by the local building code requirements.  The following sections
   detail typical installation densities for different applications.

 4.2.1. HVAC Device Density

   HVAC room applications typically have sensors/actuators and
   controllers spaced about 50ft apart.  In most cases there is a 3:1
   ratio of sensors/actuators to controllers.  That is, for each room
   there is an installed temperature sensor, flow sensor and damper
   actuator 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 since the devices are mandated or optional as
   defined by the specified HVAC application.  Air handlers typically
   serve one or two floors of the building.  Chillers and boilers may be
   installed per 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.





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 4.2.2. 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.

 4.2.3. 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 tether many lights together into a single
   zone.  Wireless systems configure each fixture independently to
   increase flexibility and reduce installation costs.

 4.2.4. 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 1 megabit/second (Mbit/s) data rates
   per camera as contrasted by the few Kbits/s needed by most other FMS
   sensing equipment.  Previously, camera systems had been deployed on
   proprietary wired high speed network. More recent implementations
   utilize wired or wireless IP cameras integrated to the enterprise
   LAN.

4.3. 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.

   Most FMS equipment will utilize 24 VAC power sources that can be
   installed by a low-voltage electrician.  He/she arrives on-site
   during the construction of the building prior to drywall 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.



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   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.  The wireless installation process must
   follow the same work flow.  The electrician installs the products as
   before and executes local functional tests between the wireless
   device to assure operation before leaving the job.   The electrician
   does not carry a laptop so the commissioning must be built into the
   device operation.



5. 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.

5.1. 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.  For new construction projects, the building enterprise IP
   network is not in place during installation of the building control
   system.  For retrofit applications, the installer will still operate
   independently from the IP network so as not to affect network
   operations during the installation phase.

   Local (ad hoc) testing of sensors and room controllers must be
   completed before the tradesperson can complete his/her work.  This
   testing allows the tradesperson to verify correct client (e.g. light
   switch) and server (e.g. light ballast) before leaving the jobsite.
   In traditional wired systems correct operation of a light
   switch/ballast pair was as simple as flipping on the light switch.
   In wireless applications, the tradesperson has to assure the same


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   operation, yet be sure the operation of the light switch is
   associated to the proper ballast.

   System level commissioning will later be deployed using a more
   computer savvy person with access to a commissioning device (e.g. a
   laptop computer).  The completely installed and commissioned
   enterprise IP network may or may not be in place at this time.
   Following are the installation routing requirements.

 5.1.1. Zero-Configuration Installation

   It MUST be possible to fully commission network devices without
   requiring any additional commissioning device (e.g. laptop).

 5.1.2. Sleeping Devices

   Sensing devices will, in some cases, utilize battery power or energy
   harvesting techniques for power and will operate mostly in a sleep
   mode to maintain power consumption within a modest budget.  The
   routing protocol MUST take into account device characteristics such
   as power budget.  If such devices provide routing, rather than merely
   host connectivity, the energy costs associated with such routing
   needs to fit within the power budget.  If the mechanisms for duty
   cycling dictate very long response times or specific temporal
   scheduling, routing will need to take such constraints into account.

   Typically, batteries need to be operational for at least 5 years when
   the sensing device is transmitting its data(e.g. 64 octets) once per
   minute.  This requires that sleeping devices MUST have minimal link
   on time when they awake and transmit onto the network. Moreover,
   maintaining the ability to receive inbound data MUST be accomplished
   with minimal link on time.

   Proxies with unconstrained power budgets oft times are used to cache
   the inbound data for a sleeping device until the device awakens.  In
   such cases, the routing protocol MUST discover the capability of a
   node to act as a proxy during path calculation; then deliver the
   packet to the assigned proxy for later delivery to the sleeping
   device upon its next awakened cycle.

 5.1.3. 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 without requiring other systemic
   devices.  Routing should allow for temporary ad hoc paths to be



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   established that are updated as the network physically and
   functionally expands.

 5.1.4. Device Replacement

   Replacement devices need to be plug-and-play with no additional setup
   compared to what is normally required for a new device.  Devices
   referencing data in the replaced device MUST be able to reference
   data in its replacement without being reconfigured to refer to the
   new device.  Thus, such a reference cannot be a hardware identifier,
   such as the MAC address, nor a hard-coded route.  If such a reference
   is an IP address, the replacement device MUST be assigned the IP
   addressed previously bound to the replaced device.  Or if the logical
   equivalent of a hostname is used for the reference, it must be
   translated to the replacement IP address.



5.2. 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.

 5.2.1. Network Domain

   The routing protocol MUST be able to support networks with at least
   2000 nodes supporting at least 1000 routing devices and 1000 non-
   routing device.  Subnetworks (e.g. rooms, primary equipment) within
   the network must support upwards to 255 sensors and/or actuators.



 5.2.2. Peer-to-Peer Communication

   The data domain for commercial FMS systems may sprawl across a vast
   portion of the physical domain.  For example, a chiller may reside in
   the facility's basement due to its size, yet the associated cooling
   towers will reside on the roof.  The cold-water supply and return
   pipes serpentine through all the intervening floors.  The feedback
   control loops for these systems require data from across the
   facility.




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   A network device MUST be able to communicate in a peer-to-peer manner
   with any other device on the network. Thus, the routing protocol MUST
   provide routes between arbitrary hosts within the appropriate
   administrative domain.



5.3. 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.  Asset tracking applications
   require monitoring movement with granularity of a minute.  This soft
   real-time performance requirement is reflected in the performance
   requirements below.

 5.3.1. Mobile Device Requirements

   To minimize network dynamics, mobile devices SHOULD not be allowed to
   act as forwarding devices (routers) for other devices in the LLN.

   A mobile device that moves within an LLN SHOULD reestablish end-to-
   end communication to a fixed device also in the LLN within 2 seconds.
   The network convergence time should be less than 5 seconds once the
   mobile device stops moving.

   A mobile device that moves outside of an LLN SHOULD reestablish end-
   to-end communication to a fixed device in the new LLN within 5
   seconds.  The network convergence time should be less than 5 seconds
   once the mobile device stops moving.

   A mobile device that moves outside of one LLN into another LLN SHOULD
   reestablish end-to-end communication to a fixed device in the old LLN
   within 10 seconds.  The network convergence time should be less than
   10 seconds once the mobile device stops.

   A mobile device that moves outside of one LLN into another LLN SHOULD
   reestablish end-to-end communication to another mobile device in the
   new LLN within 20 seconds.  The network convergence time should be
   less than 30 seconds once the mobile devices stop moving.

   A mobile device that moves outside of one LLN into another LLN SHOULD
   reestablish end-to-end communication to a mobile device in the old
   LLN within 30 seconds.  The network convergence time should be less
   than 30 seconds once the mobile devices stop moving.



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5.4. 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 mechanisms must
   therefore be tailored to fit these resource constrained devices.

 5.4.1. Limited Processing Power for Non-routing Devices.

   The software size requirement for non-routing devices (e.g. sleeping
   sensors and actuators) SHOULD be implementable in 8-bit devices with
   no more than 128KB of memory.

 5.4.2. Limited Processing Power for Routing Devices

   The software size requirements for routing devices (e.g. room
   controllers) SHOULD be implementable in 8-bit devices with no more
   than 256KB of flash memory.

5.5. Addressing

   Facility Management systems require different communication schemes
   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.

   As with any network communication, broadcasting should be minimized.
   This is especially a problem for small embedded devices with limited
   network bandwidth.  In many cases a global broadcast could be
   replaced with a multicast since the application knows the application
   domain.  Broadcasts and multicasts are typically used for network
   joins and application binding in embedded systems.

 5.5.1. Unicast/Multicast/Anycast

   Routing MUST support anycast, unicast, and multicast.





5.6. Manageability

   In addition to the initial installation of the system (see Section
   5.1), it is equally important for the ongoing maintenance of the
   system to be simple and inexpensive.



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 5.6.1. 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 routed packets sent and received, number of
   routing failures (no route available), neighbor table members, and
   routing table entries.

 5.6.2. Route Tracking

   Route diagnostics SHOULD be supported providing information such as
   path quality; number of hops; available alternate active paths with
   associated costs.  Path quality is the relative measure of 'goodness'
   of the selected source to destination path as compared to alternate
   paths.  This composite value may be measured as a function of hop
   count, signal strength, available power, existing active paths or any
   other criteria deemed by ROLL as the path cost differentiator.



5.7. 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.  Path adaptation
   will reduce latency if the path costs consider hop count as a cost
   attribute.

 5.7.1. Path Cost

   The routing protocol MUST support a metric of route quality and
   optimize path selection according to such metrics within constraints
   established for links along the paths. These metrics SHOULD reflect
   metrics such as signal strength, available bandwidth, hop count,
   energy availability and communication error rates.

 5.7.2. Path Adaptation

   Communication paths MUST adapt toward the chosen metric(s) (e.g.
   signal quality) optimality in time.







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 5.7.3. Route Redundancy

   The routing layer SHOULD be configurable to allow secondary and
   tertiary paths to be established and used upon failure of the primary
   path.

 5.7.4. Route Discovery Time

   Mission critical commercial applications (e.g. Fire, Security)
   require reliable communication and guaranteed end-to-end delivery of
   all messages in a timely fashion.  Application layer time-outs must
   be selected judiciously to cover anomalous conditions such as lost
   packets and/or path discoveries; yet not be set too large to over
   damp the network response.  If route discovery occurs during packet
   transmission time, it SHOULD NOT add more than 120ms of latency to
   the packet delivery time.

 5.7.5. Route Preference

   Route cost algorithms SHOULD allow the installer to optionally select
   'preferred' paths based on the known spatial layout of the
   communicating devices.

6. 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 pass 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.



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   Initial system startup after a controlled outage or unexpected power
   failure puts tremendous stress on the network and on the routing
   algorithms.  An FMS system is comprised of a myriad of control
   algorithms at the room, area, zone, and enterprise layers.  When
   these control algorithms are at quiescence, the real-time data
   changes are small and the network will not saturate.  However, upon
   any power loss, the control loops and real-time data quickly atrophy.
   A ten minute outage may take many hours to regain control.

   Upon restart all lines-powered devices power-on instantaneously.
   However due to application startup and self tests, these devices will
   attempt to join the network randomly.  Empirical testing indicates
   that routing paths acquired during startup will tend to be very
   oblique since the available neighbor lists are incomplete.  This
   demands an adaptive routing protocol to allow for path optimization
   as the network stabilizes.



7. Security Considerations

   Security policies, especially wireless encryption and device
   authentication needs to be considered, especially with concern to the
   impact on the processing capabilities and additional latency incurred
   on the sensors, actuators and controllers.

   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.   Single tenant owner occupied
   office buildings installing lighting or HVAC control are candidates
   for implementing low or even no security on the LLN.  Antithetically,
   military or pharmaceutical facilities require strong security
   policies.  As noted in the installation procedures above, security
   policies must be facile to allow no security during the installation
   phase (prior to building occupancy), yet easily raise the security
   level network wide during the commissioning phase of the system.



7.1. Security Requirements

 7.1.1. Authentication

   Authentication SHOULD be optional on the LLN.  Authentication SHOULD
   be fully configurable on-site. Authentication policy and updates MUST
   be routable over-the-air.  Authentication SHOULD occur upon joining
   or rejoining a network.  However, once authenticated devices SHOULD


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   NOT need to reauthenticate with any other devices in the LLN.
   Packets may need authentication at the source and destination nodes,
   however, packets routed through intermediate hops should not need
   reauthentication at each hop.



 7.1.2. Encryption

7.1.2.1. Encryption Types

   Data encryption of packets MUST optionally be supported by use of
   either a network wide key and/or application key.  The network key
   would apply to all devices in the LLN.  The application key would
   apply to a subset of devices on the LLN.

   The network key and application keys would be mutually exclusive.
   The routing protocol MUST allow routing a packet encrypted with an
   application key through forwarding devices that without requiring
   each node in the path have the application key.

7.1.2.2. Packet Encryption

   The encryption policy MUST support encryption of the payload only or
   the entire packet.  Payload only encryption would eliminate the
   decryption/re-encryption overhead at every hop providing more real-
   time performance.



 7.1.3. Disparate Security Policies

   Due to the limited resources of an LLN, the security policy defined
   within the LLN MUST be able to differ from that of the rest of the IP
   network within the facility yet packets MUST still be able to route
   to or through the LLN from/to these networks.

 7.1.4. Routing Security Policies To Sleeping Devices

   The routing protocol MUST gracefully handle routing temporal security
   updates (e.g. dynamic keys) to sleeping devices on their 'awake'
   cycle to assure that sleeping devices can readily and efficiently
   access then network.






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8. IANA Considerations

   This document includes no request to IANA.



9. Acknowledgments

   In addition to the authors, J. P. Vasseur, David Culler, 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

10.1. Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.



10.2. Informative References

   [I-D.ietf-roll-terminology] Vasseur, J., "Terminology in Low
   power And Lossy Networks", draft-ietf-roll-terminology-00 (work
   in progress), October 2008.









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11. Appendix A: Additional Building Requirements

   Appendix A contains additional building requirements that were deemed
   out of scope for ROLL, yet provided ancillary substance for the
   reader.

11.1. Additional Commercial Product Requirements

11.1.1.  Cost

   The total installed infrastructure cost including but not limited to
   the media, required infrastructure devices (amortized across the
   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.

11.1.2. Wired and Wireless Implementations

   Vendors will likely not develop a separate product line for both
   wired and wireless networks.  Hence, the solutions set forth must
   support both wired and wireless implementations.

11.1.3. 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.

11.1.4.  Support of Application Layer Protocols

11.1.4.1. BACnet Building Protocol

   BACnet is an ISO world-wide application layer IP protocol.  Devices
   implementing ROLL routing protocol should support the BACnet
   protocol.






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11.1.5. Use of Constrained Devices

   The network may be composed of a heterogeneous mix of full, battery
   and energy harvested powered devices.  The routing protocol must
   support these constrained devices.

11.1.5.1.   Energy Harvested Sensors

   Devices utilizing available ambient energy (e.g. solar, air flow,
   temperature differential)for sensing and communicating  should be
   supported by the solution set.



11.2.    Additional Installation and Commissioning Requirements

11.2.1.  Device Setup Time

   Device and Network setup by the installer must take no longer than 20
   seconds per device installed.

11.2.2.  Unavailability of an IP network

   Product commissioning must be performed by an application engineer
   prior to the installation of the IP network (e.g. switches, routers,
   DHCP, DNS).



11.3.    Additional Network Requirements

11.3.1.  TCP/UDP

   Connection based and connectionless services must be supported

11.3.2.  Interference Mitigation

   The network must automatically detect interference and seamlessly
   migrate the network hosts channel to improve communication.  Channel
   changes and nodes response to the channel change must occur within 60
   seconds.

11.3.3.  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


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   5 or less hops in each direction.  This requirement assumes network
   quiescence and a negligible turnaround time at the destination node.

11.3.4.  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% Application layer errors on all messages.

   Therefore application layer messages will fail no more than once
   every 100,000 messages.

11.3.5.  Merging Commissioned Islands

   Subsystems are commissioned by various vendors at various times
   during building construction.  These subnetworks must seamlessly
   merge into networks and networks must seamlessly merge into
   internetworks since the end user wants a holistic view of the system.

11.3.6.  Adjustable System Table Sizes

   Routing must support adjustable router table entry sizes on a per
   node basis to maximize limited RAM in the devices.

11.3.7.  Communication Distance

   A source device may be upwards to 1000 feet from its destination.
   Communication may need to be established between these devices
   without needing to install other intermediate 'communication only'
   devices such as repeaters.

11.3.8.  Automatic Gain Control

   For wireless implementations, the device radios should incorporate
   automatic transmit power regulation to maximize packet transfer and
   minimize network interference regardless of network size or density.






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11.3.9. IPv4 Compatibility

   The routing protocol must support cost-effective intercommunication
   among IPv4 and IPv6 devices.

11.3.10. Proxying for Sleeping Devices

   Routing must support in-bound packet caches for low-power (battery
   and energy harvested) devices when these devices are not accessible
   on the network.

   These devices must have a designated powered proxying device to which
   packets will be temporarily routed and cached until the constrained
   device accesses the network.

11.3.11. Device and Network 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. Network routers should maintain previous
   packet flow information temporally to minimize overall network
   overhead.



11.4. Additional Performance Requirements

11.4.1.  Data Rate Performance

   An effective data rate of 20kbits/s is the lowest acceptable
   operational data rate acceptable on the network.

11.4.2. Firmware Upgrades

   To support high speed code downloads, routing MUST support transports
   that provide parallel downloads to targeted devices yet guarantee
   packet delivery.  In cases where the spatial position of the devices
   requires multiple hops, the algorithm must recurse through the
   network until all targeted devices have been serviced.  Devices
   receiving a download MAY cease normal operation, but upon completion
   of the download must automatically resume normal operation.

11.4.3. 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.


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11.4.4. Path Persistence

   To eliminate high network traffic in power-fail or brown-out
   conditions previously established routes SHOULD be remembered and
   invoked prior to establishing new routes for those devices reentering
   the network.



11.5. Additional Network Security Requirements

 11.5.1. Encryption Levels

   Encryption SHOULD be optional on the LLN.  Encryption SHOULD be fully
   configurable on-site.  Encryption policy and updates SHOULD be
   transmittable over-the-air and in-the-clear.

 11.5.2. Security Policy Flexibility

   In most facilities authentication and encryption will be turned off
   during installation.

   More complex encryption policies might be put in force at
   commissioning time.  New encryption policies MUST be allowed to be
   presented to all devices in the LLN over the network without needing
   to visit each device.



12. Appendix B: FMS Use-Cases

   Appendix B contains FMS use-cases that describes the use of sensors
   and controllers for various applications with a commercial building
   and how they interplay with energy conservation and life-safety
   applications.

   The Vooruit arts centre is a restored monument which dates from 1913.
   This complex monument consists of over 350 different rooms including
   a meeting rooms, large public halls and theaters serving as many as
   2500 guests.  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.






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12.1. 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
   lock all the outer doors, turn the alarms on, switch off heating and
   lights, etc.

   The "building locked" or "building unlocked" event needs to be
   delivered to a subset of all the sensors and actuators. It can be
   beneficial if those field devices form a group (e.g. "all-sensors-
   actuators-interested-in-lock/unlock-events). Alternatively, the area
   and zone controllers could form a group where the arrival of such an
   event results in each area and zone controller initiating unicast or
   multicast within the LLN.

   This use case is also described in the home automation, although the
   requirement about preventing the "popcorn effect" I-D.ietf-roll-home-
   routing-reqs] can be relaxed a bit in building automation. It would
   be nice if lights, roll-down shutters and other actuators in the same
   room or area with transparent walls execute the command around (not
   'at') the same time (a tolerance of 200 ms is allowed).

12.2. 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 or dimmed.  In a
   building with many rooms it can happen quite frequently that someone
   forgets to switch off the HVAC and lighting, thereby wasting valuable
   energy.  To prevent this occurrence, the facility manager might
   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.

12.3. 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-resistant 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 using asset
   tracking and low-power wireless technologies would reduce a heavy
   burden on working hours.


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   It is important that these messages are delivered very reliably and
   that the power consumption of the sensors/actuators attached to this
   safety equipment is kept at a very low level.



12.4. Life Cycle of Field Devices

   Some field devices (e.g. smoke detectors) are replaced periodically.
   The ease by which devices are added and deleted from the network is
   very important to support augmenting sensors/actuators during
   construction.

   A secure mechanism is needed to remove the old device and install the
   new device.  New devices need to be authenticated before they can
   participate in the routing process of the LLN. After the
   authentication, zero-configuration of the routing protocol is
   necessary.

12.5. Surveillance

   Ingress and egress are real-time applications needing response times
   below 500msec, for example for cardkey authorization.  It must be
   possible to configure doors individually to restrict use on a per
   person basis with respect to time-of-day and person entering.  While
   much of the surveillance application involves sensing and actuation
   at the door and communication with the centralized security system,
   other aspects, including tamper, door ajar, and forced entry
   notification, are to be delivered to one or more fixed or mobile user
   devices within 5 seconds.

12.6. 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 set
   off an alarm and alert the mobile personnel on their user device
   (e.g. PDA).  All emergency exits are instantly unlocked and the
   emergency lighting guides the visitors to these exits.  The necessary
   sprinklers are activated and the electricity grid monitored if it
   becomes necessary to shut down some parts of the building. Emergency
   services are 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.




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   These life critical applications ought to take precedence over other
   network traffic.  Commands entered during these emergencies have to
   be properly authenticated by device, user, and command request.



12.7. Public Address

   It should be possible to send audio and text messages to the visitors
   in the building.  These messages can be very diverse, e.g. ASCII text
   boards displaying the name of the event in a room, audio
   announcements such as delays in the program, lost and found children,
   evacuation orders, etc.

   The control network is expected be able to readily sense the presence
   of an audience in an area and deliver applicable message content.

































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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
   Schneider Electric
   Technopole 38TEC T3
   37 quai Paul Louis Merlin
   38050 Grenoble Cedex 9
   France

   Phone: +33 4 76 57 66 15
   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: ???
   Fax:   ???


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   Email: wouter@vooruit.be
















































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