From the Rocks of Mars to the Slums of Cambodia: The Unexpected Evolution of Research

Khaled A. Harras, Ph.D.

Assistant Teaching Professor Founder and Director of the Networking Systems Lab (NSL)

School of Computer ScienceCarnegie Mellon University

Outline

• Story 1: – Evolution: From 4 nodes to 1.1Billion

• Story 2: – Operation: How does all this roughly work?

• Story 3: – Mobility: Common problems and solutions

• Story 4:– DTNs: The unexpected evolution of research

The Internet in 1969…

Source:http://www.sharpnet.co.uk

The Internet in 1971…

The Internet in 1977…

The Internet in 1999…

Source:http://www.caida.org

The Internet: Some Stats…

…More Stats…

…More Stats…

Source:http://broadbandanalyst.co.uk/

Asia has “started” using the Internet!

Story Punch-line…From To

• Research is the core for enabling this…

Research Results…

Outline

• Story 1: – Evolution: From 4 nodes to 1.1Billion

• Story 2: – Operation: How does all this roughly work?

• Story 3: – Mobility: Common problem and solutions

• Story 4:– DTNs: The unexpected evolution of research

Class Experiment…

• Small game to send messages…• What are the problems we can have?

– OPEN DISCUSSION…

Protocol Layers

Source: http://www.fidis.net/resources/deliverables/hightechid/int-d37003/doc/6/ and http://www.satmagazine.com/cgi-bin/display_article.cgi?number=1342678280

Networking Problems

• What are the problems we can have?– Connection establishment– Reliability– Flow control– Error control– Multiple applications– Many protocols– Routing– Congestion Control– …….!

Example: Routing

Source: http://www.h3c.com/portal/ and http://www.trainsignaltraining.com/

• Build Routing Tables

• Lookup address• Forward packets

Outline

• Story 1: – Evolution: From 4 nodes to 1.1Billion

• Story 2: – Operation: How does all this roughly work?

• Story 3: – Mobility: Common problems and solutions

• Story 4:– DTNs: The unexpected evolution of research

Today’s Internet: Simple View

Can we handle mobility… ?

• Increased wireless network deployment, and available Mobile devices

• High mobility and user expectation: “I must have network access…

NO MATTER WHAT..!!!”

Mobility: Just the beginning…

Source: Chetan Sharma Consulting

Solutions: Single-hop wireless

Solutions: Ad hoc Networks

Solutions: Mesh Networks

So… Can we handle Mobility..?

Outline

• Story 1: – Evolution: From 4 nodes to 1.1Billion

• Story 2: – Operation: How does all this roughly work?

• Story 3: – Mobility: Common problems and solutions

• Story 4:– DTNs: The unexpected evolution of research

Today’s Internet: Unstated Assumptions

• A path exists between endpoints– Routing protocols find the best path,

or even “a path”• Small end-to-end RTT

– Millisecond range• End to end reliability works well

– Especially for low data loss rates– Loss = Congestion

• Packet switching is the “right” abstraction– IP does best effort delivery for each packet

separately

The Rocks of Mars…

• In 1998 the CCSDS (Consultative Committee for Space Data Systems) founders teamed with Vint Cerf to develop the IPNSIG formed in September 1999.

• Objective: Define the architecture and protocols for an InterPlanetary InterNet: IPN

• Vision: A network of Internets

Inter-Planetary Internet A 30 year vision

Fine, those guys are just crazy… Why do “we” care..?

The Rise of New Applications

New “Common” Assumptions• Very large delays

– RTT could range from milliseconds to days– Ex: propagation between Earth and Mars

• Intermittent/disconnected links and paths– End to end connectivity might “never” exist– Routers may need significant persistent storage

• High link error rates– RF interference, light or acoustic interference– Loss is due to corruptions, not congestion

• Heterogeneous underlying networks and protocols– Some specialized networks may not run IP, and run

customized protocols that better suit them

IPN “Upgraded” to DTN Delay/Disruption Tolerant Networks

• DTNRG was formed in 2002 to generalize concepts introduced by the IPNRG

• Goal: achieve interoperability among heterogeneous networks in “extreme environments”

• Outcome: DTN Architecture and many protocols

How about other “simpler” applications…?

The Slums of Cambodia…

Are you kidding..! Who will pay for this…?

4 Billion PeopleEarning less than $2,000/year

< $2,000 4,000

‘The Bottom of the Pyramid’

Middle Classin developing

countries$2,000—$20,000 2,000

WealthyNations

Annual Purchasing Power in $US

> $20,000

PopulationIn Millions

100

Source: Prahalad & Hammond, Harvard Business Review, Vol. 80, Issue 9 (Sep. 2002), pp48-58

emerging‘mass’ markets

adjacent markets

The Bottom of the Pyramid• 3-4 billion people with per-capita equivalent

purchasing power less that US$2,000 per year• Could grow to 6-8 billion over the next 25 years• Most live in rural villages or urban slums and shanty

towns• Motivated towards urbanization and education• Dharavi, one of the poorest villages in India:

– 85% have a TV, 50% have a pressure cooker, 21% have a telephone… but can’t afford a house!

• Even the poorest of the poor in Bangladesh:– Devote 7 percent of income to communications

services (GrameenPhone)

http://www.wri.org/meb/wrisummit/pdfs/hart.pdf

The future of DTNs

• Mobile devices are starting to converge and have access to multiple networks

• Shouldn’t we take advantage of these multiple networks? Specially in challenged environments?

• Numerous Problems...

Outline

• Story 1: – Evolution: From 4 nodes to 1.1Billion

• Story 2: – Operation: How does all this roughly work?

• Story 3: – Mobility: Common problem and solutions

• Story 4:– DTNs: The unexpected evolution of research

• What to take from this talk…?

Research is a MUST!

Thank You..!

Questions…?

Contribution I: Delay Tolerant Mobile Networks (DTMNs)

• DTMN Architecture– Controlled flooding schemes– Evaluation via simulation

• Summary and Conclusions– We can significantly reduce the cost of

flooding– Few high-end nodes make a big

difference– The challenge is to “tweak the knobs”

D

S• MANETs rely on end-to-end routes• What do we do in sparse mobile

networks?– At that point in time: Flooding

delivers… too expensive– Can we “simply” reduce the cost?

Contribution II: Clustered DTMNs and Messenger Scheduling

• Summary and Conclusions– No “best scheme”; tradeoffs depend

on the network/traffic patterns– Picking the “best” scheme is a

challenge and depends on which metric has more importance; we provide such knowledge

– Adaptive strategies are very useful in such scenarios D

S

• What happens if “clusters” are formed?• Clustered DTMNs

– Use dedicated “messengers” between “regions”

– Point to point vs Path travel– Messenger management: Ownership

and Scheduling Algorithms– Evaluation via analysis and simulation

Contribution IV: Intermittent Connectivity

• Summary and Conclusions– Improvement due to bundling, single

connections, and smaller RTT– Mini-bundles is a major parameter– Solution requires no network change for

deployment

D

S• Shift focus to a single device experiencing “Disruption” rather than “Delay”

• Intermittent Connectivity & DBS-IC– View data while offline– An SA “bundles” data, delivers to MA

whenever possible– Evaluation via implementation

AP

AP

AP

• How do we make use of available opportunistic connections?

DBS-IC

ParaNets