PowerPoint Presentation

1The ZigBee IP StackIPv6-based stack for 802.15.4 networks

Robert CragiePacific Gas and Electric CompanyChair, ZigBee Security Task GroupCo-chair, ZigBee IP Stack GroupCo-chair, IETF LWIG Working Group

2011 ZigBee Alliance. All rights reserved.10/13/091ZigBee stack introduction2011 ZigBee Alliance. All rights reserved.

10/13/092The ZigBee stack specification is defined in a document with ZigBee reference base 053474ZigBee 2004053474r06ZigBee 2006053474r13ZigBee PROReleased 2007053474r18Basis for ZigBee SE 1.0ZigBee IP a completely different stackZigBee Stack Evolution32011 ZigBee Alliance. All rights reserved.

10/13/093ZigBee SE 1.0/PRO gaining momentum in the US (esp. Texas), Australia and the UKIn the US, NIST SGIP was given a mandate to assist development of US-wide standards for the Smart GridThe main edict is that standards must be openBased on IETF and IEEE standards at the lower layersThe ZigBee Alliance wanted to propel the momentum achieved with ZigBee SE 1.0/PRO going forwardInitiated development of ZigBee SE 2.0 and ZigBee IP stack specifications with supporting test documentationWhy a new, different stack?42011 ZigBee Alliance. All rights reserved.

10/13/094It is clear that being able to use multiple MAC/PHYs gives maximum flexibility in premisesThe ZigBee and HomePlug Alliances therefore jointly developed the marketing and technical requirements for SE 2.0Split into SE 2.0 application layer and underlying stackSE 2.0 application layer is stack agnostic as it is based on TCPThe ZigBee IP stack is aimed at 802.15.4 networksZigBee is also developing guidelines for interfacing SE2.0 to HomePlug powerline and other IEEE-based stacks (Ethernet, 802.11)Other MAC/PHYs52011 ZigBee Alliance. All rights reserved.

10/13/095The ZigBee IP stack2011 ZigBee Alliance. All rights reserved.

10/13/096ZigBee IP stack diagram7802.15.4 MACIPv6TCPUDPNetwork Management(ND, RPL)6lowpan adaptation802.15.4 PHYApplication SecurityZigBee SE 2.0ZigBee IP stackStack Security2011 ZigBee Alliance. All rights reserved.

10/13/097A collection of independent standard specifications (e.g. RFCs) does not produce a standards-based stack which is interoperable across products from different manufacturersZigBee IP specification is a super-specificationA specification of other standard specificationsIdentifies required standard specificationsClarifies modes of operationInteroperabilityStreamliningZigBee IP specification82011 ZigBee Alliance. All rights reserved.

10/13/098IEEE 802.15.4-2006 MAC/PHYIETF 6lowpan-hc adaptation layerIETF 6lowpan-nd neighbor discoveryIPv6 network layerRH4 routing headerHop-by-hop header RPL optionTCP/UDP transport layerIETF ROLL RPL routingNon-storing modePANA/EAP/EAP-TTLSv0/TLS securityPublic key (ECC and RSA) and PSK cipher suitesmDNS/DNS-SD service discovery supportZigBee IP stack highlights92011 ZigBee Alliance. All rights reserved.

10/13/099802.15.4-2006 standard established for over four yearsMany chipset vendorsCheap, low power radiosBasis for earlier ZigBee devicesPotential to upgrade over-the-airRFD (reduced function device) aimed at sleepy, battery-operated devicesSleepy device wakes up infrequently, sends data then goes back to sleep

IEEE 802.15.4-2006 MAC/PHY102011 ZigBee Alliance. All rights reserved.

10/13/0910802.15.4 has small PDUsMaximum PHY PDU is 127 bytesIP datagrams have a typical MTU of 1280 bytesIETF 6lowpan-hcHeader compression to optimize limited bandwidth40 octets to 3 octetsFragmentationAccommodate IPv6 datagramAutoconfiguration of IPv6 addresses based on MAC addressesInternet draftdraft-ietf-6lowpan-hc-15IETF 6lowpan-hc adaptation layer112011 ZigBee Alliance. All rights reserved.

10/13/0911RFC 4861 neighbor discovery aimed at hosts where router is always on-link6lowpan topology is quite differentA ZigBee IP network is 6lowpan topologyIETF 6lowpan-nd neighbor discovery12RFC 4861 topology 6lowpantopology RouterHost6lowpan border router (6LBR)6lowpan router (6LR)6lowpan host (6LH)2011 ZigBee Alliance. All rights reserved.

10/13/09126lowpan-nd produced to specify neighbor discovery for 6lowpan devicesUses host-initiated and unicast transactions where possible to help sleepy devicesNo redirectsOptions for disseminating 6lowpan-wide dataPrefix informationContext information for header compressionBorder router informationAddress registration mechanismMultihop DADNeighbor lifetimeInternet draftdraft-ietf-6lowpan-nd-15IETF 6lowpan-nd neighbor discovery (2)132011 ZigBee Alliance. All rights reserved.

10/13/0913The use of IPv4 is deprecatedRunning out of addresses6lowpan designed for IPv6 to produce efficient MAC PDUs based on autoconfigured IPv6 addressesThe Internet of Things can only be truly realized using IPv6One additional IPv6 header definedRH4 routing headerOne additional option for hop-by-hop headerRPL option

IPv6 network layer142011 ZigBee Alliance. All rights reserved.

10/13/0914Similar to deprecated RH0Header does not have to contain IP addressesUsed for source routing within a 6lowpanRPL non-storing modeMust not be used in the general InternetInternet draftdraft-ietf-6man-rpl-routing-header-02

RH4 routing header152011 ZigBee Alliance. All rights reserved.

10/13/0915Data plane ancillary information for RPL DODAGCarried alongside dataControl plane information relatively infrequent Limited ability to use control plane information for route repairUsed for RPL instance selection and route repairNot to be used in the general InternetInternet draftdraft-ietf-6man-rpl-option-02Hop-by-hop header RPL option162011 ZigBee Alliance. All rights reserved.

10/13/0916TCP to support HTTPWeb technology-based M2MUniversalSome challenges for lossy and low-power networksUDP to support CoAPDevelopment in IETF CoRE WGRESTful protocol for constrained devicesRESTful HTTP/XML proposed for ZigBee SE 2.0Data model based on Common Information Model (CIM)XML schema to describe presentation layerContent compression being consideredgzip/deflateEXI (efficient XML interchange)

TCP/UDP transport172011 ZigBee Alliance. All rights reserved.

10/13/0917Follows conventional network access modelIf it aint broke, dont fix it!EAP and TLS are already widely usedPANA is appropriate transport mechanism for 6lowpanPANA/EAP/EAP-TTLSv0/TLS security18Security stack diagramPANAEAP-TTLSv0EAPTLS2011 ZigBee Alliance. All rights reserved.

10/13/0918PANA (Protocol for Authentication and Network Access) (RFC 5191) specifiedEAP lower layerTransport over UDPSimilar concept to EAPOL (802.1X)Why not use EAPOL?More complex topology than 802.3/802.11No guaranteed direct access to authenticatorUDP transport efficiently optimized in 6lowpan-hcPANA relay extension developed for 6lowpan networksdraft-ohba-pana-relay-03PANA192011 ZigBee Alliance. All rights reserved.

10/13/0919EAP (RFC 3748): Extensible Authentication ProtocolExtensible packet format for carrying multiple authentication methods (EAP method)Specifies derived key hierarchy (MSK, EMSK)EAP-TTLSv0 (RFC 5281) is an EAP method for Transport Layer Security (TLS)Simple extension to EAP-TLS (RFC 5216) to provide a phase for securely transporting additional dataUsed to transport network key for frame security at the MAC layerUses TLS handshake to provide mutual authenticationEAP and EAP-TTLSv0202011 ZigBee Alliance. All rights reserved.

10/13/0920TLS 1.2 (RFC 5246) specifiedTwo mandatory cipher suitesTLS_PSK_WITH_AES_128_CCM_8TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8Optional cipher suiteTLS_DHE_RSA_WITH_AES_128_CCM_8AES-128-CCM used for AEAD cipherImplemented in many 802.15.4 chipsetsCipher suites in internet draftsdraft-mcgrew-tls-aes-ccm-00draft-mcgrew-tls-aes-ccm-ecc-01TLS212011 ZigBee Alliance. All rights reserved.

10/13/0921Typical security model22L2 secured networkPANA PaCPANA PRETLS ClientPANA PAAEAP AuthenticatorTLS ServerEAP PeerUnauthenticated node2011 ZigBee Alliance. All rights reserved.

10/13/0922ROLL: Routing Over Low power and Lossy networks802.15.4 networks are characterized as low power and lossyBuilds a DODAG (Destination-Oriented Directed Acyclic Graph) comprised of 6lowpan routers to a border router (DODAG root)Data flow implicitly to rootNon-storing mode means source routes have to be stored at root to communicate from rootInternet draftdraft-ietf-roll-rpl-19IETF ROLL RPL routing232011 ZigBee Alliance. All rights reserved.

10/13/0923mDNS: draft-cheshire-dnsext-multicastdns-14Method of hosting a DNS server on every device and using multicast to send a request within a local domainCurrent draft applies to link-local domain onlySome additional considerations needed for site local domain and group addressingDNS-SD: draft-cheshire-dnsext-dns-sd-10Use of DNS records in service discoveryNamespacing and mechanisms appropriate to service discovery above name resolutionZigBee SE 2.0 defines additional service _smartenergymDNS and DNS-SD242011 ZigBee Alliance. All rights reserved.

10/13/0924Missing partsMultiple subnet behaviorOther considerations252011 ZigBee Alliance. All rights reserved.

10/13/0925Protocols specified do not fit perfectly togetherThere are overlaps and gapsGaps have to be filled somehowPANA relay is a good example of further work undertaken to fill in a gapOther work is neededNeighbor exchange protocol for link status and alternative L2 addressLink status needed for routingAlternative L2 address (IEEE address in 802.15.4) needed for frame security processingMissing parts262011 ZigBee Alliance. All rights reserved.

10/13/0926Not specifically a ZigBee IP issueZigBee SE 2.0 needs to work over multiple subnets in the premisesSome work needed to rationalize prefixes within subnetsWork being done in v6opsdraft-herbst-v6ops-cpeenhancements-00

Multiple subnet behavior272011 ZigBee Alliance. All rights reserved.

10/13/0927

Example of multiple subnets28

ZigBee IPWiFiEthernetHomePlug

PLC2011 ZigBee Alliance. All rights reserved.

10/13/0928

Example ZigBee SE 2.0 deployment29HAN

Utility backend serverUtility ESIUtility AMI networkThird party network (e.g. Internet)

Third partybackend server

Third party ESICommissioned- only deviceUtility only registered deviceUtility and third party registered deviceNetwork-only secured trafficNetwork and application secured traffic2011 ZigBee Alliance. All rights reserved.

10/13/0929Progress2011 ZigBee Alliance. All rights reserved.

10/13/0930Numerous vendorsChipset vendorsOEM productStack suppliersAimed at resource constrained devicesIP-based open source can be adaptedContiki/uIPAlready supports 6lowpanlwIPLimited IPv6 supportTinyOSCode sizeNot yet fully known as stacks still experimentalStack support312011 ZigBee Alliance. All rights reserved.

10/13/093110 test events held so far in the US and the UKGating test event in August 201010 implementers past gating eventAim to have specification ready for members to start certification at the end of May 2011

Test events and timeline322011 ZigBee Alliance. All rights reserved.

10/13/0932Thank you!robert.cragie@gridmerge.com2011 ZigBee Alliance. All rights reserved.

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