zigbee technical overview

8/6/2019 ZigBee Technical Overview

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Copyright 2008 ZigBeeTM

Alliance. All Rights Reserved.

Wireless Control That Simply Works

ZigBee Technical Overview

Wireless JapanTokyo, Japan

July 23, 2008


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Wireless Control That Simply WorksZigBeeTM

Alliance |Copyright 2008. All Rights Reserved.

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Presented by:

Drew Gislason

President and CTO

San Juan Software

Former ZigBee Alliance Secretary to the

Application Framework Group

E-mail: [email protected]


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Latest Version of the ZigBee Specification: ZigBee-2007

The ZigBee-2007 Specification contains definition of twofeature sets:

ZigBee feature set

ZigBee PRO feature set The ZigBee and ZigBee PRO feature sets interoperate,

network wise, in a limited way within a single network:

ZigBee devices may join PRO networks as an end device

ZigBee PRO devices may join ZigBee networks as an end

device ZigBee and ZigBee PRO devices fully interoperate at the

application level on the same network

ZigBee and ZigBee PRO devices fully interoperate ifstandard security mode is used on the network


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ZigBee Feature Set

ZigBee Feature Set

Ad-hoc self forming networks

Mesh and Cluster Tree

Unicast, broadcast and groupcast

Logical Device Types

Coordinator, Router and End Device

Optional Network Manager for PAN ID conflict and frequency agility

Standard Application Services

Device and Service Discovery

Optional acknowledged service

Optional fragmentation/re-assembly service

Cluster Library support to standard definition of application messages

Mechanism to support mix of Public andManufacturer Specific profiles in thesame network, all supported by standard ZigBee network and applicationfeatures


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ZigBee Feature Set

ZigBee Feature Set (continued)

Security

Authentication and Encryption at Network and Application levels.

Symmetric Key with AES-128

Key Hierarchy: Network Keys and Application Link Keys (optional)

Qualification

Platform Conformance Certification

Manufacturer Specific Product Certification

Public Profile Product Certification

Regularly Scheduled Interoperability Events


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ZigBee PRO Feature Set


Ad-hoc self forming networks

Mesh only

Many to One and Source Routing Enhancements

Network layer multicastSame Logical Device Types as ZigBee feature set (ZC, ZR, ZED)

Network Manager for PAN ID conflict resolution and frequency agility

Same Application Services as ZigBee feature set

Two security modes:

Standard security compatible with ZigBee feature set High security


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ZigBee PRO Features (continued)

Security

Symmetric Key with AES-128

Authentication and Encryption at Network and Application levels.

Key Hierarchy: Master Keys (optional), Network Keys and Link Keys(optional)

Qualification

Platform Conformance Certification

Manufacturer Specific Product Certification

Public Profile Product Certification

Regularly Scheduled Interoperability Events


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ZigBee and ZigBee PRO Protocol Stack


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Stack Architecture

IE E E 802.15.4defined

ZigBee TM Alliancedefined

End manufacturerdefined

Layerfunction

Layerinterface

Ph ysical (PHY) Layer

Medium A ccess Control (MAC ) Layer

Network (NW K) Layer-

Application Support Sublayer (APS)

APS Message

BrokerManagemen

t

APS Security

Management

Reflector

Management

ApplicationObject 240

Application

Object 1

Application (APL) Layer

ZigBee Device Object

(ZDO )

Endpoint 240

APSD E -SAP

Endpoint 1

APSD E -S AP

Endpoint 0

APSD E -S AP

NLDE -SAP

M LD E-S APM LM E-SAP

PD-SAP PLM E -S AP

Security

Management

Message

Broker

Routing

Management

Network

Management

2.4 GHz Radio 868/915 MHz Radio

Security

Service

Provider

ZDOPublic

Interfaces

Application F ramework

Z

DOManagementPlane

APSME-

SAP

NL

ME-SAP

NLME -SAP


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Application Device Type Model

802.15.4

Device Type

FFD

FullFunction Device

RFD

ReducedFunctionDevice

Distinguishes the

type of hardwareplatform

Logical

Device Type

ZigBee

Coordinator

ZigBee

Router

Distinguishes theLogical Device

Types deployed in

a specific network

ZigBee

End

Device

Application

Device Type

e.g.

Light

Sensor

e.g.

Lighting

Controller

Distinguishes the

type of device from

an end-user

perspective...

ZigBee products are a combination of Application, Logical, and Physical device types

Profiles may define specific requirements for this combination, but can also leave this up to

manufacturers


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ZigBee and ZigBee PRO Network

Communication Model (Mesh Routing)

ZigBee End Device (RFD or FFD)

ZigBee Router (FFD)

ZigBee Coordinator (FFD)

Mesh Link

Note: Mesh networking is a bandwidth and RAM efficient routing method. Mesh is

supported by both ZigBee and ZigBee Pro networks.


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ZigBee Network Communication Model

(Cluster Tree Routing)


ZigBee Router (FFD)


Note: Cluster Tree Routing is the backup routing method in ZigBee (SP1)

networks, used if mesh is busy.


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ZigBee PRO Network Communication

Model (Many to One and Source Routing)


ZigBee Router (FFD)


Concentrator

Mesh Link

Note: Concentrators may be any router in the network (not just the ZC). Source

routing allows scaling in large networks with limited RAM in most nodes.


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ZigBee and ZigBee PRO

Network Topologies and Routing

Mesh network routing permits path formation from any source device to anydestination device via a path formed by routing packets through neighbors

Table routing employs a simplified version ofAd Hoc On Demand Distance VectorRouting (AODV), an Internet Engineering Task Force (IETF) Mobile Ad Hoc Networking(MANET) submission

Used in both the ZigBee and ZigBee PRO feature sets

Cluster tree network routing directs packets up and down the tree structurecreated through network formation until they reach their destination

Must use netmask type tree routing (up and down the parent/child links)

Fails if parent/child links are not usable over time

Used only in the ZigBee feature set

Many to One and Source Routingfeatures address limitations in Mesh networkrouting where table size requirements are large in certain data transmissionscenarios

Many to One allows any device in the network to route data to a well known concentratorthrough a single routing table entry in every device

Multiple concentrators in a single network are possible

Source routing allows a concentrator to route responses back to each device supplying aMany to One data request without additional route table entries

End Devices are low powerin either feature set since they dont participate inrouting and only communicate through their parent (routers or coordinator) atapplication specified times


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ZigBee Application Model

Devices are modeled throughApplication Objects

Application Objects communicatethrough the exchange ofClusters andAttributes

Each Profile Object can contain single or

multiple Clusters and Attributes Binding mechanism ensures

interoperable exchange ofClusters/Attributes

Clusters/Attributes are sent

Directly to destination application

objects(thereby to target device)

Generic ZigBee device functions areprovided through ZigBee Device Objects

Light Switch

ZigBee Device

Objects

(e.g. ZigBee End

Device)Light Switch

Object

Light Controller

ZigBee Device

Objects

(e.g. ZigBee

Coordinator)Lighting Control

Object

On-Off


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ZigBee Application Model

Application Profiles are an agreement on a series of messages

defining an application space (for example, Home Automation or

Smart Energy)

Endpoints are a logical extension added to a single ZigBee radio

which permits support for multiple applications, addressed by the

Endpoint number (1-240)

Key Relationships:

Maximum of240 Endpoints per ZigBee Device (Endpoint 0 is reserved to

describe the generic device capabilities and Endpoint 255 is reserved for

broadcasting to all endpoints, Endpoints 241-254 are reserved for future use)

One Application Profile described per Endpoint


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Security Services Provider (SSP)

Security at each layer:

Network (NWK) layer security for network command frames (route request, routereply, route error)

Application (APL) layer security forApplication Support Sub-layer (APS) frames

Two Security Modes

Standard Mode (ZigBee and PRO feature sets) Two NWK keys, APL securityvia NWK key. Ability to switch NWK keys. Optional use ofApplication Link Keysfor pairs of communicating devices at APL.

High Security Mode (PRO feature set only) Two NWK keys, separate LinkKeys for pairs of communicating devices at APL. Master Keys with the TrustCenter for key transport and key establishment. Ability to switch NWK keys.Entity authentication between all pairs of communicating devices.

Security Implementation Trust Center Creates and distributes the Network Keys. Manages switch from

active to secondary Network Key (Standard and High Security Modes).Optionally supports Master Keys and Trust Center Link Key establishment andtransport (Optional in Standard security mode and mandatory in High Securitymode)


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Security Services Provider (SSP)

Key Hierarchy

Master Key (could be programmed in or provided *in the clear* from the

Trust Center) High Security mode only

Network Key (used for all NWK commands from any device and forAPS

messaging) Standard and High Security modes Link Keys (used for each pair of communicating devices) Standard

and High Security modes

Features in either Security Mode

Authentication and Encryption

Freshness (frame counters)

Message Integrity


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Security Service in Standard Mode

Unsecured

key-transport

NWKKey

Basis of security between

two (or group of) devices

Factory or out-of-

band installed

Frame Security

ServiceSecures all frames

(except key-transport)

Key-Transport Service

Unsecured key-transport of

NWK key

Authentication Service

Secure authenticationthat a device shares a

NWK key.

NWK key is used as basis

of security services


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Security Service in High Security Mode

Unsecured

key-transport

Link Key/NWKKey

Basis of security between

two (or group of) devices

MasterKey

Basis for long-term security

between two devices

Factory

installed

Frame Security Service

Secures all frames

(except key-transport)


Secure key-transport ofgrouplink keys


Secure key-transport ofmasterkeys

Authentication Service

Secure authentication that adevice shares a link key.

Link key is used as basis of

security services

Secured key-transport

from trust center

SKKE

protocol or

Key

Transport

Secured key-transport

of group link keys


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Feature Sets

Agreement of stack parameters, settings and policies for a familyof application profiles (including manufacturer specific applicationprofiles)

Current feature sets:

ZigBee (mesh routing+cluster tree routing) Beacon-less, mesh network

Supports any application profile

ZigBee PRO(mesh routing with enhancements)

Beacon-less, mesh network

Enhanced support for large networks

Enhanced security mode

Application layer compatibility with ZigBee feature set

Feature set identifier supplied in beacon payload. Devices joinappropriate networks supporting desired feature set.


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Deployment

Commissioning

Devices are programmed for a specific feature set or to join specificalternate feature set networks

If multiple networks with the same feature set are present, the applicationneeds mechanisms to help the device select the correct network

Provision security keys (unless they are provided over the air)

Establish command/control relationships in the network (binding)

Commissioning can take place via a dedicated commissioning tool(laptop or PDA) or via installation key presses on a remote control orthe device itself

Common Maintenance Operations requiring application supportAdding new devices to an existing network

Combining networks

Replacing devices in a network


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Summary

The ZigBee and ZigBee PRO feature sets provide an ad-hoc,self forming network topology supporting mesh routing

ZigBee and ZigBee PRO feature sets provide an agreementon specific configuration parameters and network settings tocreate multi-vendor interoperable networks

ZigBee application profiles are an agreement on messageformats and command/response exchanges which provide adocumented method to create interoperable device types

Current status on the ZigBee Ecosystem:

45 product listings for the ZigBee and ZigBee PRO feature setson 21 platforms provides application developers with a richenvironment to deploy interoperable products.

28 Smart Energy and Home Automation product manufacturersat last months interoperability event!


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