IoT Protocol Stack.pdf

-

1. IOT PROTOCOL STACK:
A LAYERED VIEW

2. LEARNING OBJECTIVES
2
•Students able to state the TCP/IP layered and IoT protocol stack
•Students able to describe challenges and requirements impact the protocols which operate at
respective layer.

3. INTRODUCTION
3

4. INTRODUCTION
4
The IoT protocol stack can be visualized as an extension of the TCP/IP layered protocol model and
is comprised of the following layers
Figure 1: IoT protocol stack

5. LINK LAYER CHALLENGES
5
Figure 2: Link layer challenges. (Source Cisco BRKIOT-2020, 2015)

6. LINK LAYER CHALLENGES
6
1.Devicecharacteristics:theIoTwillencompassawidespectrumof“things”thatspanfromfully
capable(non-constrained)computenodestohighlyconstraineddevices.theLinklayerisresponsible
forthenuancesofthephysicaltransmissiontechnology,framing,mediaaccesscontrol,and
retransmission.
2.Trafficcharacteristics:varywidelydependingontheapplication’sdemandsandnatureofdevices.
Someapplications:
1.Haverelaxedrequirementsandverytight
2.Generateshortbursttrafficandlong-tailedtraffic
3.Deterministicandrandomcommunications
3.Accesscharacteristics:IoTdevicesintheseenvironmentsmayconnecttothenetworkusingamixof
wirelessandwiredtechnologies.deviceswhenconnectedwirelesslymaybeeithermobileor
stationary.Itdependingonthelogisticsofthedeploymentmayrequireeitherlong-rangeorshort-
rangeconnectivitysolutions.
4.Scalability:Thetechnologiesofferseveralappealingcharacteristicsthatmakethemagoodfitfor
theIoT.Forinstance,cellulartechnologiesaresubjecttothespectrumcrunchproblemandwireless
meshtechnologiessuffer

7. INTERNET LAYER
7
ManyIoTdeploymentsconstitutelow-powerandlossynetworks(LLNs).Thesenetworkscomprisedof
alargenumberofconstrainedembeddeddeviceswithlimitedpower,memory,andprocessing
resources.TheyareinterconnectedusingavarietyofLinklayertechnologies,suchasIEEE802.15.4,
Bluetooth,Wi-Fi,orpower-linecommunication(PLC)links.
LLNspresentthefollowingfivechallengestotheInternetlayeroftheprotocolstack:

8. INTERNET LAYER CHALLENGES
8 Figure 3: IoT challenges for the Internet layer. (Source Cisco BRKIOT-2020, 2015)

9. INTERNET LAYER CHALLENGES (LLNS)
9
1.NodesinLLNsoperatewithahard,verysmallboundonstate:Internetlayerprotocolsneed
tominimizetheamountofstatethatneedstobekeptpernodeforroutingortopology
maintenancefunctions
2.LLNsareoptimizedforsavingenergy:Varioustechniquesareusedincludingemploying
extendedsleepcycleswheretheembeddeddevicesonlywakeupandconnecttothenetwork
whentheyhavedatatosend.
3.TrafficpatternswithinLLNs:point-to-point,point-to-multipoint,andmultipoint-to-pointflows.
Assuch,unicastandmulticastconsiderationsshouldbetakenintoaccountwhendesigning
protocolsforthislayer
4.LLNsbeemployedoverLinklayertechnologiescharacterizedwithrestrictedframesizes:
routingprotocolsforLLNsshouldbeadaptedspecificallyforthoseLinklayers.
5.LLNsinherentlyunreliablewithtime-varyinglosscharacteristics:Theprotocolsneedtooffer
highreliabilityunderthosecharacteristics

10. APPLICATION PROTOCOL LAYER
10
•ApplicationprotocolsareresponsibleforhandlingthecommunicationbetweenApplication
Entities,i.e.,things,gateways,andapplications.
•Theytypicallysupporttheflowofdatafromthingstoapplicationsandtheflowofcommandor
controlinformationinthereversedirection.

11. APPLICATION PROTOCOL LAYER-DATA SERIALIZATION FORMATS
11
•should be able to interpret the data from IoT devices with minimal format translations and a priori
knowledge
Mapping between the formats
•Data formats influence device resource usage in two facets: in local processing demands and
communication efficiency.
•The local processing demands include the processing required to serialize memory objects into
data encoded in messages
•The processing required to parse the encoded messages into memory objects.
The impact on device resource utilization
•When devices are connected over low-bandwidth wireless links, the data serialization format of
application protocols should be chosen carefully to maximize the use of the available bandwidth.
the impact have on network bandwidth utilization

12. APPLICATION PROTOCOL LAYER-COMMUNICATION PARADIGMS
12
Application protocols support different communication patterns. These patterns enable varying
paradigms of interaction between IoT applications and devices.
1.Request/Response Versus Publish/Subscribe
2.Blocking Versus Non-blocking

13. REQUEST/RESPONSE VS PUBLISH/SUBSCRIBE
13
ThisparadigmiswellsuitedforIoT
deploymentsthathaveoneormoreofthe
followingcharacteristics:
•Thedeploymentfollowsaclient-server
architecture.
•Thedeploymentrequiresinteractive
communication:bothendpointshave
informationtosendtotheotherside.
•Thereceiptofinformationneedstobefully
acknowledged(e.g.,forreliability).
Figure 4: Request/Response paradigm

14. REQUEST/RESPONSE VS PUBLISH/SUBSCRIBE
14
thepub/submodeliswellsuitedforIoT
deploymentsthatcanbenefitfromthe
followingcharacteristics:
•Loosecouplingbetweenthecommunicating
endpoints
•Betterscalability
Figure 4: Publish/subscribe paradigm

15. BLOCKING VS NON-BLOCKING
15
Intheblockingmode,theendpointoriginating
arequestmustwaittogetaresponsetoits
request,aftertherequestedoperationhas
finishedontheotherendpoint.Thisinvolves
potentiallylongorunknownwaittimes
Figure 5: Blockingparadigm

16. BLOCKING VS NON-BLOCKING
16
Inthenon-blockingmode,theendpoint
originatingarequestdoesnotwaituntilthe
otherendpointhasfullyservicedtherequest.
Rather,itexpectsapromptacknowledgment
oftherequesttogetherwithaspecified
reference,sothattheoriginatorcanretrieve
theoutcomeoftherequestedoperationata
laterpointoftime.
Figure 6: Non-Blockingparadigm

17. RESTFUL CONSTRAINT
17
Some application protocols adhere to a set of constraints defined by the representational state transfer
(REST) architectural paradigm.
REST is a distributed
client-server software
architecture style
concluded on a set of constraints
that collectively define the REST
architectural style
ROY FIELDING

18. FORMAL REST CONSTRAINTS
18
Client-Server
Communication
Model
Stateless
Communication
Cacheable
Communication
Layered
Architecture
Uniform
Interfaces
Code on
Demand

19. FORMAL REST CONSTRAINTS
19
1.Client-Server Communication Model: server focuses on functions such as data storage,
whereas clients focus on the user interface and user state.
2.Stateless Communication: Session state is maintained by the client, which passes all the
information necessary to service a particular request in the request itself.
3.Cacheable Communication: Responses from the server may be cacheable by clients and
intermediate nodes
4.Layered Architecture: the system comprised of a layered architecture that includes clients,
servers, and potentially multiple intermediate nodes interspersed between them for better
scalability.
5.Uniform Interfaces: Means server responses should announce available actions and resources.
All interactions between clients and servers are governed by uniform interfaces.
6.Code on Demand: Client functionality may be extended or modified by the server through the
transfer of executable pieces of code that can be executed on the client

20. APPLICATION SERVICES LAYER
20
verticalsolutionsareimplementedinsiloswithproprietarycommunicationstacksandverytight
couplingbetweenapplicationsanddevices.Theparadigmcanbebestdescribedas“one
application-onedevice.”Thiscreatescomplexityandincreasesthecostofthesolution’sinitial
developmentandongoingmaintenance.
“anyapplication-anydevice”istheparadigmthatfitsinbetweentheapplicationsandthedevices
whichrequiredlayerofabstraction.thisabstractionlayerprovidesacommonsetofservicesthat
enablesanapplicationtointerfacewithpotentiallyanydevicewithoutunderstandingapriorthe
specificsandinternalsofthatdevice.