i-1 Internet Intro

Taekyoung Kwontkkwon@snu.ac.kr

Internet Background

• Era of Cold War– Sputnik in 1957 -> ARPA, NASA

• Government sponsored goal– Department of Defense (DoD)

• To maintain communication via computers even with threat of war– No central authority– Designed to operate while some systems

are broken2

Another motivation• Naïve researchers

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ARPA -> Defense Advanced Research Projects Agency (DARPA)

Paradigm shift

• Circuit switching → Packet Switching– data to be transmitted is divided into

small packets of information and labeled to identify the sender and recipient

– sent over a network and then reassembled at their destination

– if any packet did not arrive or was not intact, original sender is requested to resend the packet

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Context

• When Packet Switching was proposed– Packet Switching is a new idea

• telco gave it a -5 on a scale of 1-10

– Computers are million dollar items and ARPA can’t buy new ones every year but minicomputers have just arrived

– Time-sharing and inter-process communication are new ideas

– Personal Computers don’t exist– Networks are expensive

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The Internet is born in 1969

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• Enable sharing of supercomputer power

• 4 nodes– UCLA– Stanford (SRI)– UC Santa Barbara– U of Utah

• Including BBN, some say 5 nodes

Zoom in to UCLA

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Interface Message Processor

1972: Robert Kahn

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2000s: middle-age

• Now it faces problems

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IP

TCP UDP

Applications

token

radio, copper, fiber

802.11 PPPEth

IP “hourglass”

IP

TCP UDP

Applications

token

radio, copper, fiber

802.11 PPPEth

diffserv

intservmcastmobile

NAT IPSEC

Expanding waist?

Internet standardization• Protocol: a set of rules governing

communication between hosts or devices

103GPP, IEEE

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• Now around 1B hosts!• But count only hosts with domain

names

Internet hosts

Network prefixes

12Source: bgp.potaroo.net

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Traffic breakdown• Cisco: By 2013 Video Will Be 90 Percent Of All Consumer IP Traffic

And 64 Percent of Mobile

Environment: trusted → untrusted

• Requires a far more secure Internet– What do we mean by security?– What aspects are the network’s

responsibility?

• Major design challenges:– Resilience to large-scale external attacks

(DDoS)– Resilience to compromised routers– Easy authentication of data– Forensics and auditing– Providing both accountability and privacy

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users: researchers → customers

• Customers demand high availability– Service is almost never interrupted

• Internet was designed for strong recovery properties– Recovering from serious failures

• How can the Internet provide 5 9’s of availability?– and doing so in a cost-effective manner– Internet currently at 2-3 9’s

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operators: nonprofit → commercial

• Operators must be able to manage their networks– Configuration– Troubleshooting– Middleboxes (proxies, firewalls, NATs, etc.)– Policy (routing, access control)

• What are the right abstractions for management?– What mechanisms best support them?

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usage: host-oriented → data-oriented

• Internet was designed around a host-oriented model– User tells client to contact another host (telnet,

ftp)• Current usage is mostly data-centric

– User wants to access particular data or service– Does not care where that service is located

• Mismatch currently handled by ad hoc mechanisms– Akamai, P2P

• Right abstractions for a data-oriented Internet?

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connectivity: e2e IP → intermittent

• Architecture assumes end-to-end IP connectivity

• In some niche settings, each link is intermittent and end-to-end connectivity is rare– Space, underwater, developing economies– Led to call for “delay-tolerant networking” (DTN)

• More generally want to shield applications from networking details– Opportunistic and context-dependent communication

• What’s the right API to enable this generality?

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New requirements• Mobility • Scalability (e.g. network prefixes)• Traffic Explosion (Especially wireless)• Multicasting/Broadcasting• Security• Delay tolerant networks (DTNs)

– E.g. vehicular ad hoc networks (VANETs) • Multimedia, realtime applications

– Video Adaptation– QoS, QoE

• Data center network• Cyber physical system (CPS)• E-911

– Should be able to disseminate emergency info– Spatial distribution

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