ALWAYS OFFLINEDelay-tolerant Networking for the Internet of Things

Daniel Austin

GRIN Technologies, Inc.

“The Connected Life Company”

daniel.austin@grintech.net

1st Annual IoT Conference

Oct 21, 2014

V1.4

ABOUT GRIN TECHNOLOGIES, INC.

• Founded July 4th 2014

• “The Connected Life Company”

• Developing Systemsware at the Intersection of Big Data and the Internet of Things

• Focused on the Connected Car

• Coming in Q3 2015: The Connected Life Server ™

FOUR BIG IDEAS FOR TODAY’S TALK

1. No “Internet of Things”, only disjoint Networks of Things

2. Delay-Tolerant Networking as a solution for the IoT

3. Strategies for DTN and VDTN architectures

4. Social cooperation and Networks of Things

“If we had computers that knew everything there was to know about things –

using data they gathered without any help from us – we would be able to track

and count everything, and greatly reduce waste, loss and cost. We would know

when things needed replacing, repairing or recalling…”

-Kevin Ashton, 1989

NETWORKS OF THINGS

HYPE CYCLES COMPARED

Gartner 2011 Gartner 2014

WHY THERE WILL BE NO “INTERNET OF THINGS”

• No clients; no servers

• No network that connects them all

• No protocols that make sense

• Intermittent, Transient, Low Value, Connectionless

Many of Our Current Assumptions About the Internet Simply Don’t Apply!

INSTEAD, DISJOINT NETWORKS OF THINGS

• Disjoint – for Security and Privacy and Management

• Functional and Context-Specific

• Mesh-based Peering Architectures

Peer 1

Peer 2

Peer3

Peer 4

Peer 1

Peer 2

Peer3

Peer 4

Public

Internet

Gateway Gateway

A DAY IN THE CONNECTED LIFE

…”a system where the Internet is connected to the physical world via ubiquitous sensors…”

By 2020 everyone, everything and

everywhere will be connected in real

time. More than 50 100 billion

connected devices will be used in the

Networked Society.

Source: http://www.ericsson.com/thinkingahead/networked_society

CHARACTERISTICS OF THE NETWORK OF

THINGS

• Many small messages

• Intermittent transmission

• Connectionless

• Stateless

• No guaranteed delivery

• Heterogeneous nodes

• Lazy/No Acknowledgements

• Mesh architectures based on proximity

• Mixed/variable security

MOBILITY + UBIQUITY REQUIRE NEW IDEAS

• TCP/IP Assumptions:

• End-to-End connection

• Short, fixed delays

• Symmetric data rates

• Low error rates

• Knowledge of network state

• Deterministic

• DTNs originated at NASA for interplanetary communications (RFC 4838 &

5050)

• Applies to all intermittently connected scenarios, including the IoT

WHAT PROBLEM(S) ARE WE SOLVING?Sensor

Networks/ IoT

Mobile Devices

Vehicle Networks

Military/ Emergency

Space Communica

tions

Low Population/

Infrastructure

Exotic Cases: Animal

Tracking

DTN

Each of these

scenarios involves

HOW DTNS WORK

TCP/IP

DTN

Source; DTN SIG

EXISTING IMPLEMENTATIONS

• Interplanetary Internet Project (NASA)

• MIT CarTel

• Haggle (Cambridge)

• Bytewalla (Android-based DTN)

• Multiple commercial VDTN projects

• Several others, all small scale or research-oriented

DTN PROTOCOL ARCHITECTURES

STORE-CARRY-FORWARD

• Every DTN networking scheme is based on the S-C-F pattern

• Requires cooperation among nodes

• Messages are (too) often replicated

• Custody transfer required for committed transfer

FLOODING VS. FORWARDING

Source: Khabbaz et al.: Delay-Tolerant Networking: A Comprehensive Survey of Recent Results

ECOLOGY OF THE IOT

• Hypothesis: The ‘Flooding’ vs.

‘Forwarding’ strategies correspond

to the r/K reproductive strategies

used in ecological environments.

• This suggests that opportunistic (r)

‘Flooding’ strategies will work best

when the network is below its

capacity, and ‘Forwarding’ (K)

strategies will work best when the

network is near capacity.

• Is the evolution of the Internet of

Things governed by the logistic

function?

ROUTING STRATEGIES COMPARED

Routing Strategy Copies Replication Objective

Epidemic unlimited high Reduce delay

Direct Delivery single N/A Serial delivery

Prophet unlimited med Probabilistic

Spray-and-Wait N copies med Limited copies

MaxProp unlimited high Reduce queue time

RAPID unlimited high Reduce propagation

CUSTODY TRANSFER

Requirements for Custody Transfer:

1) Be closer to the bundle’s ultimate destination.

2) Certify long period bundle storage ability.

3) Certify the ability and willingness to strive for

the ultimate goal: depositing the bundle at its

ultimate destination.

4) Possess enough power to remain usefully

active over long periods.

5) Be cooperative and take advantage of every

chance to realize the ultimate goal.

Source: Khabbaz et al.: Delay-Tolerant Networking: A Comprehensive Survey of Recent Results

THE CAP THEOREM AND DTNS

Source: DTN SIG

PERFORMANCE OF DTNS

Important Factors:

• Probability of Delivery

• the ratio of messages delivered to the total

• Hopcount

• the number of individual nodes involved in the message transfer

• Dropped Messages

• the total number of messages not delivered

• Started Messages

• the total number of messages

• Latency is

• the time between sending and delivery

• Overhead ratio

• How many times each message was duplicated

SOCIAL COOPERATION AND DTN ROUTING

• Ad-hoc and opportunistic networks display social behavior

• Cooperation us crucial in DTNs

• Social routing for DTNs based on:

• Similarity

• Community

• Friendship

• Selfishness

• Incentives

• Social routing can reduce propagation overhead and increase delivery

probabilities

• Games such as Give2Get and Tit-for-Tat can be solved in limited cases

CHALLENGES AND NEXT STEPS FOR DTNS

DTNs offer a solution to a number of networking problems in pervasive

computing and the IoT…

…but still need to prove their worth and solve outstanding issues:

• Rapidly address security/sensitive information transfer

• Expand existing implementations especially for VDTNs

• Design routing based on social factors

KEY TAKEAWAYS

• Delay-Tolerant Networking provides a solution for transient and intermittent

networks based on the Store-Carry-Forward design pattern

• Vehicles and sensor networks are natural targets for DTNs, but challenges

remain, especially around security, receipt reliability and routing

• DTNs have a social and cooperative aspect that rewards cooperation and

fairness while discouraging selfish behavior (and may display ecological

behaviors as well).

is where nothing connects.

THANKS!“When everyone’s life is connected, that’s when the

Singularity will happen.”

Daniel Austin

GRIN Technologies, Inc.

The Connected Life Company

daniel.austin@grintech.net

http://www.grintech.net

@daniel_b_Austin

@GRINTechInc