Iot

Protocols of IoT
Ankit Anand
7th Sem., B.Tech. (IT),
S.O.E., CUSAT.
26-09-2017 1

Topics in this Presentation
What is Internet of Things?
How IoT Works?
Current Status & Future Prospect of IoT
The Future of IoT
 IoT Data Link Protocol
Network Layer Routing Protocols
 Network Layer Encapsulation Protocols
 Session Layer Protocols
2

What is IoT?
The Internet of Things (IoT) is the network of physical objects or
"things" embedded with electronics, software, sensors, and network
connectivity, which enables these objects to collect and exchange data.
IoT allows objects to be sensed and controlled remotely across
existing network infrastructure, creating opportunities for more direct
integration between the physical world and computer-based systems,
and resulting in improved efficiency, accuracy and economic benefit.
3

"Things," in the IoT sense, can refer to a wide variety
of devices such as heart monitoring implants, biochip
transponders on farm animals, electric clams in coastal
waters, automobiles with built-in sensors, DNA analysis
devices for environmental/food/pathogen monitoring or
field operation devices that assist fire-fighters in search
and rescue operations.
These devices collect useful data with the help of
various existing technologies and then autonomously flow
the data between other devices.
4

The concept of the Internet of Things first became
popular in 1999, through the Auto-ID Center at MIT and
related market-analysis publications. R
Radio-frequency identification (RFID) was seen as a
prerequisite for the IoT at that point. If all objects and
people in daily life were equipped with identifiers,
computers could manage and inventory them. Besides
using RFID, the tagging of things may be achieved through
such technologies as near field communication, barcodes,
QR codes, bluetooth, and digital watermarking.
History of IoT
5

How IoT Works?
Internet of Things is not the result of a single novel technology;
instead, several complementary technical developments provide
capabilities that taken together help to bridge the gap between the virtual
and physical world. These capabilities include:
Communication and cooperation
Addressability
Identification
Sensing
Actuation
Embedded information processing
Localization
User interfaces
6

How IoT Works?
7
RFID Sensor Smart Tech Nano Tech
To identify
and track the
data of
things
To collect and
process the
data to detect
the changes in
the physical
status of things
To enhance the
power of the
network by
devolving
processing
capabilities to
different part of
the network.
To make the
smaller and
smaller things
have the ability
to connect and
interact.

The Structure of IoT
The IoT can be viewed as a gigantic network consisting of
networks of devices and computers connected through a series
of intermediate technologies where numerous technologies
like RFIDs, wireless connections may act as enablers of this
connectivity.
Tagging Things : Real-time item traceability and addressability
by RFIDs.
Feeling Things : Sensors act as primary devices to collect data
from the environment.
Shrinking Things : Miniaturization and Nanotechnology has
provoked the ability of smaller things to interact and connect
within the “things” or “smart devices.”
Thinking Things : Embedded intelligence in devices through
sensors has formed the network connection to the Internet. It
can make the “things” realizing the intelligent control.
8

Current Status & Future Prospect of IoT
9
“Change is the only thing permanent in this world”

Different IOT Protocols
• IoT Data Link Protocol
• Network Layer Routing Protocols
• Network Layer Encapsulation Protocols
• Session Layer Protocols

IoT Data Link Protocol
• In this section, we discuss the datalink layer protocol standards. The
discussion includes physical (PHY) and MAC layer protocols which are
combined by most standards.

IEEE 802.15.4
• IEEE 802.15.4 is the most commonly used IoT standard for MAC. It
defines a frame format, headers including source and destination
addresses, and how nodes can communicate with each other. The
frame formats used in traditional networks are not suitable for low
power multi-hopnetworking in IoT due to their overhead. In 2008,
IEEE802.15.4e was created to extend IEEE802.15.4 and support low
power communication. It uses time synchronization and channel
hopping to enable high reliability, low cost and meet IoT
communications requirements. Its specific MAC features can be
summarized as follows [802.15.4]:

Specific MAC features can be summarized as follows
[802.15.4]:
• Scheduling: The standard does not define how the scheduling is done but it needs to be
built carefully such that it handles mobility scenarios. It can be centralized by a manager
node which is responsible for building the schedule, informing others about the schedule
and other nodes will just follow the schedule
• Synchronization: Synchronization is necessary to maintain nodes’ connectivity to their
neighbors and to the gateways. Two approaches can be used: acknowledgment-based or
frame-based synchronization. In acknowledgement-based mode, the nodes are already
in communication and they send acknowledgment for reliability guarantees, thus can be
used to maintain connectivity as well. In frame-based mode, nodes are not
communicating and hence, they send an empty frame at pre-specified intervals (about
30second typically).

WirelessHART
• WirelessHART is a datalink protocol that operates on the top of IEEE 802.15.4
PHY and adoptsvTime Division Multiple Access (TDMA) in its MAC. It is a
secure and reliable MAC protocol that uses advanced encryption to encrypt
the messages and calculate the integrity in order to offer reliability. The
architecture, as shown in Figure 3 consists of a network manager, a security
manager, a gateway to connect the wireless network to the wired networks,
wireless devices as field devices, access points, routers and adapters. The
standard offers end-to-end, per-hop or peer-to- peer security mechanisms.
End to end security mechanisms enforce security from sources to destinations
while per-hop mechanisms secure it to next hop only[Kim08, Raza10].

Z-Wave
Z-Wave is a low-power MAC protocol designed for home automation
and has been used for IoT communication, especially for smart home
and small commercial domains. It covers about 30- meter point-to-
point communication and is suitable for small messages in IoT
applications, like light control, energy control, wearable healthcare
control and others. It uses CSMA/CA for collision detection and ACK
messages for reliable transmission. It follows a master/slave
architecture in which the master control the slaves, send them
commands, and handling scheduling of the whole network [Z-Wave].

Bluetooth Low Energy
• Bluetooth low energy or Bluetooth smart is a short range communication
protocol with PHY and MAC layer widely used for in-vehicle networking. Its
low energy can reach ten times less than the classic Bluetooth while its
latency can reach 15 times. Its access control uses a contentionless MAC with
low latency and fast transmission. It follows master/slave architecture and
offers two types of frames: adverting and data frames. The Advertising frame
is used for discovery and is sent by slaves on one or more of dedicated
advertisement channels. Master nodes sense advertisement channels to find
slaves and connect them. After connection, the master tells the slave it’s
waking cycle and scheduling sequence. Nodes are usually awake only when
they are communicating and they go to sleep otherwise to save their power
[Decuir10, Gomez12].

Network Layer Routing Protocols
• In this section, we discuss some standard and non-standard protocols
that are used for routing in IoT applications. It should be noted that
we have partitioned the network layer in two sublayers:
• routing layer which handles the transfer the packets from source to
destination, and an
• encapsulation layer that forms the packets. Encapsulation
mechanisms will be discussed in the next section.

RPL
Routing Protocol for Low-Power and Lossy Networks (RPL) is distance-vector protocol that
can support a variety of datalink protocols, including the ones discussed in the previous
section. It builds a Destination Oriented Directed Acyclic Graph (DODAG) that has only one
route from each leaf node to the root in which all the traffic from the node will be routed to.
At first, each node sends a DODAG Information Object (DIO) advertising itself as the root.
This message is propagated in the network and the whole DODAG is gradually built. When
communicating, the node sends a Destination Advertisement Object (DAO) to its parents,
the DAO is propagated to the root and the root decides where to send it depending on the
destination. When a new node wants to join the network, it sends a DODAG Information
Solicitation (DIS) request to join the network and the root will reply back with a DAO
Acknowledgment (DAO-ACK) confirming the join. RPL nodes can be stateless, which is most
common, or stateful. A stateless node keeps tracks of its parents only. Only root has the
complete knowledge of the entire DODAG. Hence, all communications go through the root
in every case. A stateful node keeps track of its children and parents and hence when
communicating inside a sub-tree of the DODAG, it does not have to go through the root
[RFC6550].

CORPL
• An extension of RPL is CORPL, or cognitive RPL, which is designed for cognitive
networks and uses DODAG topology generation but with two new modifications
to RPL. CORPL utilizes opportunistic forwarding to forward the packet by choosing
multiple forwarders (forwarder set) and coordinates between the nodes to
choose the best next hop to forward the packet to. DODAG is built in the same
way as RPL. Each node maintains a forwarding set instead of its parent only and
updates its neighbor with its changes using DIO messages. Based on the updated
information, each node dynamically updates its neighbor priorities in order to
construct the forwarder set [Aijaz15].

CARP
• Channel-Aware Routing Protocol (CARP) is a distributed routing protocol designed for
underwater communication. It can be used for IoT due to its lightweight packets. It considers
link quality, which is computed based on historical successful data transmission gathered
fromneighboring sensors, to select the forwarding nodes. There are two scenarios: network
initialization and data forwarding. In network initialization, a HELLO packet is broadcasted from
the sink to all other nodes in the networks. In data forwarding, the packet is routed from sensor
to sink in a hop- by-hop fashion. Each next hop is determined independently. The main problem
with CARP is that it does not support reusability of previously collected data. In other words, if
the application requires sensor data only when it changes significantly, then CARP
dataforwarding is not beneficial to that specific application. An enhancement of CARP was done
in E-CARP by allowing the sink node to save previously received sensory data. When new data
is needed, E-CARP sends a Ping packet which is replied with the data from the sensors nodes.
Thus, E-CARP reduces the communication overhead drastically [Shou15].

Network Layer Encapsulation Protocols
• One problem in IoT applications is that IPv6 addresses are too long
and cannot fit in most IoT datalink frames which are relatively much
smaller. Hence, IETF is developing a set of standards to encapsulate
IPv6 datagrams in different datalink layer frames for use in IoT
applications. In this section, we review these mechanisms briefly.

6LoWPAN
• IPv6 over Low power Wireless Personal Area Network (6LoWPAN) is
the first and most commonly used standard in this category. It
efficiently encapsulates IPv6 long headers in IEEE802.15.4 small
packets, which cannot exceed 128 bytes. The specification supports
different length addresses, low bandwidth, different topologies
including star or mesh, power consumption, low cost, scalable
networks, mobility, unreliability and long sleep time.

6TiSCH
• 6TiSCH working group in IETF is developing standards
to allow IPv6 to pass through TimeSlotted Channel
Hopping (TSCH) mode of IEEE 802.15.4e datalinks. It
defines a Channel Distribution usage matrix consisting
of available frequencies in columns and time-slots
available for network scheduling operations in rows.
This matrix is portioned into chucks where each chunk
contains time and frequencies and is globally known
to all nodes in the network.

Session Layer Protocols
• This section reviews standards and protocols for message passing in
IoT session layer proposed by different standardization organizations.
Most of the IP applications, including IoT applications use TCP or UDP
for transport. However, there are several message distribution
functions that are common among many IoT applications; it is
desirable that these functions be implemented in an interoperable
standard ways by different applications. These are the so called
“Session Layer” protocols described in this section.

MQTT
• Message Queue Telemetry Transport (MQTT) was introduced by IBM in 1999
and standardized by OASIS in 2013 [Locke10 , Karagiannis15]. It is designed to
provide embedded connectivity between applications and middleware’s on
one side and networks and communications on the other side. It follows a
publish/subscribe architecture, as shown in Figure 5 , where the system
consists of three main components: publishers, subscribers, and a broker.
From IoT point of view, publishers are basically the lightweight sensors that
connect to the broker to send their data and go back to sleep whenever
possible. Subscribers are applications that are interested in a certain topic, or
sensory data, so they connect to brokers to be informed whenever new data
are received. The brokers classify sensory data in topics and send them to
subscribers interested inthe topics

SMQTT
• An extension of MQTT is Secure MQTT (SMQTT) which uses encryption based
on lightweight attribute based encryption. The main advantage of using such
encryption is the broadcast encryption feature, in which one message is
encrypted and delivered to multiple other nodes, which is quite common in
IoT applications. In general, the algorithm consists of four main stages: setup,
encryption, publish and decryption. In the setup phase, the subscribers and
publishers register themselves to the broker and get a master secret key
according to their developer’s choice of key generation algorithm. Then, when
the data is published, it is encrypted, published by the broker which sends it
to the subscribers and finally decrypted at the subscribers which have the
same master secret key. The key generation and encryption algorithms are not
standardized. SMQTT is proposed only to enhance MQTT security feature
[Singh15].

AMQP
The Advanced Message Queuing Protocol (AMQP) is another session
layer protocol that was designed for financial industry. It runs over TCP
and provides a publish/ subscribe architecture which is similar to that
of MQTT. The difference is that the broker is divided into two main
components: exchange and queues, as shown in Figure 6. The exchange
is responsible for receiving publisher messages and distributing them
to queues based on pre-defined roles and conditions. Queues basically
represent the topics and subscribed by subscribers which will get the
sensory data whenever they are available in the queue [AMQP12].

CoAP
The Constrained Application Protocol (CoAP) is another session layer protocol
designed by IETF Constrained RESTful Environment (Core) working group to
provide lightweight RESTful (HTTP) interface. Representational State Transfer
(REST) is the standard interface between HTTP client and servers. However, for
lightweight applications such as IoT, REST could result in significant overhead
and power consumption. CoAP is designed to enable low-power sensors to use
RESTful services while meeting their power constrains. It is built over UDP,
instead of TCP commonly used in HTTP and has a light mechanism to provide
reliability. CoAP architecture is divided into two main sublayers: messaging and
request/response. The messaging sublayer is responsible for reliability and
duplication of messages while the request/response sublayer is responsible for
communication. As shown in Figure 7 , CoAP has four messaging modes:
confirmable, nonconfirmable, piggyback and separate

CoAP
• Confirmable and nonconfirmable modes represent the reliable and
unreliable transmissions, respectively while theother modes are used
for request/response. Piggyback is used for client/server direct
communication where the server sends its response directly after
receiving the message, i.e., within the acknowledgment message. On
the other hand, the separate mode is used when the server response
comes in a message separate from the acknowledgment, and may
take some time to be sent by the server. As in HTTP, CoAP utilizes GET,
PUT, PUSH, DELETE messages requests to retrieve, create, update,
and delete, respectively

XMPP
• Extensible Messaging and Presence Protocol (XMPP) is a messaging protocol that
was designed originally for chatting and message exchange applications. It was
standardized by IETF more than a decade ago. Hence, it is well known and has
proven to be highly efficient over the internet. Recently, it has been reused for
IoT applications as well as a protocol for SDN. This reusing of the same standard is
due to its use of XML which makes it easily extensible. XMPP supports both
publish/ subscribe and request/ response architecture and it is up to the
application developer to choose which architecture to use. It is designed for near
real-time applications and, thus, efficiently supports low-latency small messages.
It does not provide any quality of service guarantees and, hence, is not practical
for M2M communications. Moreover, XML messages create additional overhead
due to lots of headers and tag formats which increase the power consumption
that is critical for IoT application. Hence, XMPP is rarely used in IoT but hasgained
some interest for enhancing its architecture in order to support IoT applications.

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