Cs542 internet system technology wst510 web architecture http an kaist ac kr courses 2012 wst510
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CS542 Internet System Technology WST510 Web Architecture http://an.kaist.ac.kr/courses/2012/wst510. 2012.2.9. Lecture #2 Sue Moon and Ben Zhao. Today’s Agenda. History of the Internet Design goals Layering End-to-end arguments. Internet History. Internet History.

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CS542 Internet System Technology WST510 Web Architecture an.kaist.ac.kr/courses/2012/wst510

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Cs542 internet system technology wst510 web architecture http an kaist ac kr courses 2012 wst510

CS542 Internet System TechnologyWST510 Web Architecturehttp://an.kaist.ac.kr/courses/2012/wst510


Lecture #2

Sue Moonand Ben Zhao

Today s agenda

Today’s Agenda

History of the Internet

Design goals


End-to-end arguments

Internet history

Internet History

Internet history1

Internet History

  • 1961Kleinrock advocates packet switching (why?)

    • In parallel, packet switching work done at RAND and NPL

  • 1962Licklider’s vision of Galactic Network

  • 1965Roberts connects 2 computers over phone line

  • 1967Roberts publishes vision of ARPANET

  • 1969BBN installs first InterfaceMsgProcessor @UCLA

  • 1970Network Control Protocol

    • assumed reliable transmission!

  • 1972public demonstration of ARPANET

  • 1972Email invented

  • 1972Kahn advocates Open Architecture networking

The problem

The Problem

Many different packet-switching networks

Only nodes on the same network could communicate

Kahn s ground rules

Kahn’s Ground Rules

Each network is independent and must not be required to change

Best-effort communication

Boxes (routers) connect networks

No global control at operations level






Kahn imagined there would be only a few networks (~20) and thus only a few routers

He was wrong


Internet evolution 1960s plan

Internet Evolution (1960s plan)

Internet evolution 1969


Internet evolution april 1971

Internet Evolution (April 1971)

Internet evolution sept 1971

Internet Evolution (Sept. 1971)

Internet evolution sept 19711

Internet Evolution (Sept. 1971)

Cs542 internet system technology wst510 web architecture an kaist ac kr courses 2012 wst510

“Today (~2000)”

History continued

History Continued

1974Cerf and Kahn paper on TCP/IP

1980TCP/IP adopted as defense standard

1983Global NCP to TCP/IP flag day

198xXNS, DECbit, and other protocols

1985NSFnet (picks TCP/IP)

198xInternet meltdowns due to congestion

1986+ Van Jacobson saves the Internet (BSD TCP)

1988Deering and Cheriton propose multicast, Morris Worm

199xQoS rises and falls

199xATM rises and falls (as an internetworking layer)

1994Internet goes commercial

200xThe Internet boom and bust

Internet design goals

Internet Design Goals

Goals clark 88

Goals (Clark’88)

Connect existing networks

Robust in face of failures (not nuclear war…)

Support multiple types of services

Accommodate a variety of networks

Allow distributed management

Easy host attachment

Cost effective

Allow resource accountability



  • As long as the network is not partitioned, two endpoints should be able to communicate

  • Failures (except network partitions) should not interfere with endpoint semantics (why?)

  • Maintain state only at end-points, why?

    • Fate-sharing

      • State dies IFF endpoint using it dies

      • eliminates network state restoration

      • Protection against a # of failures, easy to engineer

    • stateless network architecture (no per-flow state)

  • Routing state is held by network (why?)

Types of services

Types of Services

  • Use of the term “communication services” already implied that they wanted application-neutral network

  • Realized TCP wasn’t needed (or wanted) by some applications

    • Remote debugging, delivery of digitized speech

  • Separated TCP from IP, and introduced UDP

    • What’s missing from UDP?

Variety of networks

Variety of Networks

  • Incredibly successful!

    • Minimal requirements on networks

    • No need for reliability, in-order, fixed size packets, etc.

  • IP over everything

    • Then: ARPANET, X.25, DARPA satellite network..

    • Now: ATM, SONET, WDM…

Host attachment

Host Attachment

  • Clark observes that the cost of host attachment may be somewhat higher

    • Because edge hosts have to be smart

  • But the administrative cost of adding hosts is very low, which is probably more important

Real goals

Real Goals

Something that works…..

Connect existing networks

Survivability (not nuclear war…)

Support multiple types of services

Accommodate a variety of networks

Allow distributed management

Easy host attachment

Cost effective

Allow resource accountability



What priority order would a commercial design have?

What would a commercially invented Internet look like?

What goals are missing from this list?

Which goals led to the success of the Internet?

Layering and other general mutterings about internet architecture

Layering and other General Mutterings about Internet Architecture

Logical communication

Logical Communication

Host A

Host B



















Physical medium

Layers interacts with corresponding layer on peer

Osi vs internet










OSI vs. Internet










Net access/



Internet (informal)

OSI (formal)

OSI: conceptually define services, interfaces, protocols

Internet: provide a successful implementation



Implications of hourglass

Implications of Hourglass

  • A single Internet layer module:

  • Allows all networks to interoperate

    • all networks technologies that support IP can exchange packets

  • Allows all applications to function on all networks

    • all applications that can run on IP can use any network

  • Simultaneous developments above and below IP

Can we shift the hourglass

Can We Shift the Hourglass?


the new IP?

Endless arguments about end to end

Endless Arguments about End-to-End

Placing functionality

Placing Functionality

  • The most influential paper about placing functionality is “End-to-End Arguments in System Design” by Saltzer, Reed, and Clark

  • The “Sacred Text” of the Internet

    • endless disputes about what it means

    • everyone cites it as supporting their position

Basic observation

Basic Observation

  • Some applications have end-to-end performance requirements

    • reliability, security, etc.

  • Implementing these in the network is very hard:

    • every step along the way must be fail-proof

  • The hosts:

    • can satisfy the requirement without the network

    • can’t depend on the network

Example reliable file transfer


Example: Reliable File Transfer

Host A

Host B





Solution 1: make each step reliable, and then concatenate them

Solution 2: end-to-end check and retry

Example cont d

Example (cont’d)

  • Solution 1 not complete

    • What happens if any network element misbehaves?

    • The receiver has to do the check anyway!

  • Solution 2 is complete

    • Full functionality can be entirely implemented at application layer with no need for reliability from lower layers

  • Is there any need to implement reliability at lower layers?

Example speech voip

Example: Speech / VoIP

  • Standard example for E2E argument

    • Packets need “semi-reliable” delivery at endpoint for transformation into audio

  • If lower layers try for “perfect reliability,”

    • Delay and retransmit at link layer

    • Result: uncontrolled delays and stream disruption

  • Instead, endpoint can tolerate some data loss

    • Rely on the ultimate “endpoint,” the human

    • “What did you just say?”

    • This is the source of much “cross-layer” work in the multimedia networking community



Implementing this functionality in the network:

  • Doesn’t reduce host implementation complexity

  • Does increase network complexity

  • Probably imposes delay and overhead on all applications, even if they don’t need functionality

  • However, implementing in network can enhance performance in some cases

    • very lossy link

What the paper says

What the Paper Says

The function in question can completely and correctly be implemented only with the knowledge and help of the application standing at the end points of the communication system. Therefore, providing that questioned function as a feature of the communication system itself is not possible. (Sometimes an incomplete version of the function provided by the communication system may be useful as a performance enhancement.)

BTW, E2E also applicable to OS and H/W design…

Conservative interpretation

Conservative Interpretation

“Don’t implement a function at the lower levels of the system unless it can be completely implemented at this level” (Peterson and Davie)

Unless you can relieve the burden from hosts, then don’t bother

Radical interpretations

Radical Interpretations

  • Don’t implement anything in the network that can be implemented correctly by the hosts

    • e.g., multicast

    • Makes network layer absolutely minimal

    • Ignores performance issues

  • Don’t rely on anything that’s not on the data path

    • E.g., no DNS

    • Makes network layer more complicated

Moderate interpretation

Moderate Interpretation

Think twice before implementing functionality in the network

If hosts can implement functionality correctly, implement it a lower layer only as a performance enhancement

But do so only if it does not impose burden on applications that do not require that functionality

Do these belong in the network

Do These Belong in the Network?



Quality of Service (QoS)?

Name resolution? (is DNS “in the network”?)

Web caches?

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