DOCSLIB.ORG

Operating Systems and Networks Networks Part 1

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Operating Systems and Networks Networks Part 1 Welcome! Operating Systems and Networks • Brief introduction of lecturer and TAs – Adrian Perrig, Professor in Department of Computer Science, Director of Network Security Group – Exercise sessions: David Barrera (PhD), Raphael Reischuk (PhD) – Labs / homeworks: Tae-Ho Lee, Chris Pappas Networks Part 1: Introduction – Network security group research area: design and implementation of secure future Internet architecture (SCION project http://www.scion-ar c hit e ct ur e .ne t ) Adrian Perrig Network Security Group ETH Zürich 2 Course Structure Lecture Style • Lectures • Student interaction is encouraged! • Homework – Please ask questions if something is unclear • Projects – Please point out any errors that you spot – • Exercise sessions Please focus on lecture instead of facebook, twitter, etc. • Quizzes • Please turn off cell phone and Wi F i during class 3 4 Minds open… … Laptops closed and cell phones / ipads off 6 Textbook and Slide Credit Problems with Being On-line During Class • Textbook: TANENBAUM, ANDREW S.; WETHERALL, DAVID J., COMPUTER NETWORKS, 5th Edition, 2011. • It takes the mind a few minutes to reach a state of deep • Slides adapted from slide deck by David Wetherall concentration • Lecture video at: – Reaching deep concentration needs to be trained, many people http://media.pearsoncmg.com/ph/streaming/esm/tanenbaum5e_videon have lost this ability due to constant / frequent interruptions otes/tanenbaum_videoNotes.html • Knowing that one cannot be interrupted increases concentration. Said another way: Expectation of interruption prevents deep concentration – Try to be off-line when studying networking! • Open laptop / iPad / cell phone used for surfing can also disrupt / interrupt people sitting behind you 7 Highly Recommended as Reference Also recommended • Larry L. Peterson and Bruce S. • Kevin R. Fall and W. Davie: Richard Stevens: “Computer Networks: A Systems Approach” “TCP/IP Illustrated, • 5th Edition Volume 1: The Protocols” • 2nd Edition, 2011 9 Also recommended Study Recommendations Computer Networking: A Top-Down Approach: Kurose and Ross • Make list of acronyms, concepts 5th Edition • Read corresponding sections in text book – Available in INFK library • Participate in exercise sessions, solve homework, Srinivasan Keshav: and DO THE PROJECTS! An Engineering Approach to Computer Networking 11 12 Homework Assignment Presentations Projects • We will have 2 hands-on projects • Assignments are posted at the end of each week and presented in the following week – Reliable communication – Routing • Projects are completed in groups of 3-4 students – Register at http://bit.ly/22OxK0S – First project will be posted by Friday midnight on course web page and presented next week 13 14 Final Grade Focus of the course • Projects & Exercises are optional – but highly recommended to do them • Networking grade = exam grade ??? • Final grade = average( Networking grade, OS grade ) 15 16 Focus of the course (2) The Main Point • Three “networking” topics: 1. To learn how the Internet works – What really happens when you “browse the web”? Distributed systems – What are TCP/IP, DNS, HTTP, NAT, VPNs, 802.11 etc. anyway? Networking 2. To learn the fundamentals of computer networks Communications • We mainly study the Networking aspects 17 18 Why learn about the Internet? From this experimental network … 1. Curiosity ARPANET ~1970 2. Understand how the system works we’re spending most of our time with – Interesting statistic: we’re spending more time online than sleeping! 3. Impact on our world (a) Dec. 1969. (b) July 1970. (c) March 1971. 4. Job prospects! 19 20 To this! Internet – Societal Impact Internet ~2005 • An enabler of societal change • An everyday institution – Easy access to knowledge used at work, home, – Electronic commerce and on-the-go – Personal relationships • Visualization contains – Discussion without censorship millions of links Attribution: By Th e Op te Project [CC-BY-2.5], vi a W i ki med i a C o mmo n s 21 22 Internet – Economic impact The Main Point (2) 1. To learn how the Internet works • An engine of economic growth 2. To learn the fundamentals of computer – Advertising-sponsored search networks – Online stores – What hard problems must they solve? – Online marketplaces – Crowdsourcing – What design strategies have proven valuable? 23 24 Why learn the Fundamentals? Fundamentals – Intellectual Interest 1. Apply to all computer networks • Example key problem: Reliability! – Any part of the Internet might fail 2. Intellectual interest – Messages might be corrupted – How to create a reliable network out of unreliable 3. Change / reinvention components? 4. Pass this course :-) • Reliability solutions – Codes to detect/correct errors – Routing around failures ... 25 26 Fundamentals – Intellectual Interest (2) Fundamentals – Reinvention Key problem Example solutions • The Internet is constantly being re-invented! Reliability despite Codes for error detection/correction (§3.2, 3.3) – Growth over time and technology trends drive failures Routing around failures (§5.2) Network growth Addressing (§5.6) and naming (§7.1) upheavals in Internet design and usage and evolution Protocol layering (§1.3) • Today’s Internet is different from yesterday’s Allocation of resources Multiple access (§4.2) like bandwidth Congestion control (§5.3, 6.3) – And tomorrow’s will be different again Security against Confidentiality of messages (§8.2, 8.6) – But the fundamentals remain the same various threats Authentic ation of communicating parties (§8.7) 27 28 Fundamentals – Reinvention (2) Fundamentals – Reinvention (3) • Examples of upheavals in the past 1-2 decades • Currently around 1.1 billion Growth / Tech Driver Upheaval Internet hosts … Emergence of the web Content Distribution Networks Digital songs/videos Peer-to-peer file sharing Falling cost/bit Voice-over-IP cal li ng Many Internet hosts IPv6 Wireless advances Mobile devices 29 30 Not a Course Goal Example Uses of Networks • Work: • To learn IT job skills – Email, file sharing, printing, … – How to configure equipment • Home: • E.g., Cisco certifications – Movies / songs, news, calls / video / messaging, e- – But course material is relevant, and we use hands-on commerce, What do these uses tell us about … tools • Mobile: why we build networks? – Calls / texts, games, videos, maps, information access … 31 32 For User Communication For Resource Sharing • • From the telephone onwards: Many users may access the same underlying resource – VoIP (voice-over-IP) – E.g., 3D printer, search index, machines in the cloud – Video conferencing →More cost effective than dedicated resources per user – Instant messaging – – Social networking Even network links are shared via statistical multiplexing →Enables remote communication – Need low latency for interactivity 33 34 Statistical Multiplexing Statistical Multiplexing (2) • Sharing of network bandwidth between users according • Example: Users in an ISP network 5 to the statistics of their demand – Network has 10 0 Mbps (units of bandwidth) 100 . – (Multiplexing just means sharing) – Each user subscribes to 5 Mbps, for videos ISP 5 – Useful because users are mostly idle and their traffic is bursty – But a user is active only 50% of the time … 5 • How many users can the ISP support? • Key question: – With dedicated bandwidth for each user: – How much does it help? – Probability all bandwidth is used: (assuming independent users) 35 36 Statistical Multiplexing (3) For Content Delivery • With 30 independent users, still unlikely (2% chance) to • Same content is delivered to many users need more than 100 Mbps! – Videos (large), songs, apps and upgrades, web pages, – Binomial probabilities … → Can serve more users with the same size network – Statistical multiplexing gain is →More efficient than sending a copy all the way to 30/20 or 1.5X each user – But may get unlucky; users will have degraded service – Uses replicas in the network 37 38 Content Delivery (2) Content Delivery (3) • Sending content from the source to 4 users takes 4 x 3 = • But sending content via replicas takes only 4 + 2 = 6 12 “network hops” in the example “network hops” User User . Source Source Replica User User 39 40 For Computer Communication To Connect Computers to the Physical World • To let computers interact with other computers • For gathering sensor data, and for manipulating the – E.g., e-commerce, backup, cloud computing world – E.g., webcams, location on mobile phones, door locks, … →Enables automated information processing across different parties • This is a rich, emerging usage (IoT: Internet of Things) 41 42 The Value of Connectivity The Value of Connectivity (2) • “Metcalfe’s Law” ~1980: Bob Metcalfe • Example: both sides have 12 nodes, but the left network – The value of a network of N nodes is has more connectivity proportional to N2 – Large networks are relatively more valuable than small ones vs + 66 connections 15 connections 15 connections : © 2009 IEEE 43 44 Parts of a Network Component Names Component Function Example application Applic ation, or app, user Uses the network Skype, iTunes, Amazon Host, or end-system, edge Supports apps Laptop, mobile, desktop device, node, source, sink Router, or switc h, node, Relays messages Access point, cable/DSL hub, intermediate system between links modem router link host Link, or c hannel Connects nodes Wires, wireless 45 46 Types of Links Wireless Links • Message is broadcast • Full-duplex – – Bidirectional Received by all nodes in range – Not a good fit with our model • Half-duplex – Bidirectional
Load more

Recommended publications
  • David D. Clark
    Designs for an Internet David D. Clark Dra Version 3.0 of Jan 1, 2017 David D. Clark Designs for an Internet Status is version of the book is a pre-release intended to get feedback and comments from members of the network research community and other interested readers. Readers should assume that the book will receive substantial revision. e chapters on economics, management and meeting the needs of society are preliminary, and comments are particularly solicited on these chapters. Suggestions as to how to improve the descriptions of the various architectures I have discussed are particularly solicited, as are suggestions about additional citations to relevant material. For those with a technical background, note that the appendix contains a further review of relevant architectural work, beyond what is in Chapter 5. I am particularly interesting in learning which parts of the book non-technical readers nd hard to follow. Revision history Version 1.1 rst pre-release May 9 2016. Version 2.0 October 2016. Addition of appendix with further review of related work. Addition of a ”Chapter zero”, which provides an introduction to the Internet for non-technical readers. Substantial revision to several chapters. Version 3.0 Jan 2017 Addition of discussion of Active Nets Still missing–discussion of SDN in management chapter. ii 178 David D. Clark Designs for an Internet A note on the cover e picture I used on the cover is not strictly “architecture”. It is a picture of the Memorial to the Mur- dered Jews of Europe, in Berlin, which I photographed in 2006.
    [Show full text]
  • List of Internet Pioneers
    List of Internet pioneers Instead of a single "inventor", the Internet was developed by many people over many years. The following are some Internet pioneers who contributed to its early development. These include early theoretical foundations, specifying original protocols, and expansion beyond a research tool to wide deployment. The pioneers Contents Claude Shannon The pioneers Claude Shannon Claude Shannon (1916–2001) called the "father of modern information Vannevar Bush theory", published "A Mathematical Theory of Communication" in J. C. R. Licklider 1948. His paper gave a formal way of studying communication channels. It established fundamental limits on the efficiency of Paul Baran communication over noisy channels, and presented the challenge of Donald Davies finding families of codes to achieve capacity.[1] Charles M. Herzfeld Bob Taylor Vannevar Bush Larry Roberts Leonard Kleinrock Vannevar Bush (1890–1974) helped to establish a partnership between Bob Kahn U.S. military, university research, and independent think tanks. He was Douglas Engelbart appointed Chairman of the National Defense Research Committee in Elizabeth Feinler 1940 by President Franklin D. Roosevelt, appointed Director of the Louis Pouzin Office of Scientific Research and Development in 1941, and from 1946 John Klensin to 1947, he served as chairman of the Joint Research and Development Vint Cerf Board. Out of this would come DARPA, which in turn would lead to the ARPANET Project.[2] His July 1945 Atlantic Monthly article "As We Yogen Dalal May Think" proposed Memex, a theoretical proto-hypertext computer Peter Kirstein system in which an individual compresses and stores all of their books, Steve Crocker records, and communications, which is then mechanized so that it may Jon Postel [3] be consulted with exceeding speed and flexibility.
    [Show full text]
  • NSFNET: the Partnership That Changed the World
    NSFNET: The Partnership that Changed the World Celebrating 20 Years of Internet Innovation and Progress November 29-30, 2007 Crystal Gateway Marriott, Arlington, Virginia Contents: Event Supporters 2 Program at a Glance 3 Detailed Agenda 4 - 8 Speaker Biographies 9 - 16 NSFNET: The Partnership that Changed the World 1 The organizers wish to thank the following organizations for supporting this event: Advanced Network & Services, Inc. www.advanced.org Cisco Systems, Inc. www.cisco.com IBM www.ibm.com Internet2 www.internet2.edu Juniper Networks www.juniper.net Merit Network, Inc. www.merit.edu National Science Foundation www.nsf.gov 2 Program at a Glance (see pages 4 - 8 for detailed program) Thursday, November 29, 2007 - General Program 7:30 - 8:30 a.m. Registration and Continental Breakfast 8:30 - 9:15 Welcome Speakers: Eric M. Aupperle and Jane Caviness The Internet History Archive Speaker: Doug Gale Introductory Comments Speaker: John H. Marburger, III Keynote - NSFNET: The Phenomenon Speaker: Douglas E. Van Houweling 9:20 - 10:35 Panel - NSFNET: The Beginnings Moderator: Lawrence Landweber 10:35 - 11:00 Break 11:00 - 11:55 Panel - NSFNET: The Solicitation & The Merit Partnership Moderator: Jane Caviness 11:55 - 12:45 Lunch 12:45 - 1:45 Panel - NSFNET: The T1—The Internet Comes of Age Moderator: Eric M. Aupperle 1:50 - 2:50 Panel - NSFNET: The T3 Backbone Service—The Internet Matures Moderator: Allan H. Weis 2:50 - 3:15 Break 3:15 - 4:35 Panel - NSFNET: The Community Moderator: Doug Gale 4:40 - 5:30 Panel - NSFNET: The Impact on Research and Science Moderator: George O.
    [Show full text]
  • Computer Networking: a Top-Down Approach, 7Th Edition
    Computer Networking A Top-Down Approach Seventh Edition James F. Kurose University of Massachusetts, Amherst Keith W. Ross NYU and NYU Shanghai Boston Columbus Indianapolis New York San Francisco Hoboken Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo Vice President, Editorial Director, ECS: Marcia Horton Acquisitions Editor: Matt Goldstein Editorial Assistant: Kristy Alaura Vice President of Marketing: Christy Lesko Director of Field Marketing: Tim Galligan Product Marketing Manager: Bram Van Kempen Field Marketing Manager: Demetrius Hall Marketing Assistant: Jon Bryant Director of Product Management: Erin Gregg Team Lead, Program and Project Management: Scott Disanno Program Manager: Joanne Manning and Carole Snyder Project Manager: Katrina Ostler, Ostler Editorial, Inc. Senior Specialist, Program Planning and Support: Maura Zaldivar-Garcia Cover Designer: Joyce Wells Manager, Rights and Permissions: Ben Ferrini Project Manager, Rights and Permissions: Jenny Hoffman, Aptara Corporation Inventory Manager: Ann Lam Cover Image: Marc Gutierrez/Getty Images Media Project Manager: Steve Wright Composition: Cenveo Publishing Services Printer/Binder: Edwards Brothers Malloy Cover and Insert Printer: Phoenix Color/ Hagerstown Credits and acknowledgments borrowed from other sources and reproduced, with ­permission, in this textbook appear on appropriate page within text. Copyright © 2017, 2013, 2010 Pearson Education, Inc. All rights reserved. Manufactured in the United States of America. This publication is protected by Copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, request forms and the appropriate contacts within the Pearson Education Global Rights & Permissions Department, please visit www.pearsoned.com/permissions/.
    [Show full text]
  • Computer Networking a Top-Down Approach 6Th Edition
    COMPUTER SIXTH EDITION NETWORKING A Top-Down Approach James F. Kurose University of Massachusetts, Amherst Keith W. Ross Polytechnic Institute of NYU Boston Columbus Indianapolis New York San Francisco Upper Saddle River Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo Vice President and Editorial Director, ECS: Art Director, Cover: Anthony Gemmellaro Marcia Horton Art Coordinator: Janet Theurer/ Editor in Chief: Michael Hirsch Theurer Briggs Design Editorial Assistant: Emma Snider Art Studio: Patrice Rossi Calkin/ Vice President Marketing: Patrice Jones Rossi Illustration and Design Marketing Manager: Yez Alayan Cover Designer: Liz Harasymcuk Marketing Coordinator: Kathryn Ferranti Text Designer: Joyce Cosentino Wells Vice President and Director of Production: Cover Image: ©Fancy/Alamy Vince O’Brien Media Editor: Dan Sandin Managing Editor: Jeff Holcomb Full-Service Vendor: PreMediaGlobal Senior Production Project Manager: Senior Project Manager: Andrea Stefanowicz Marilyn Lloyd Printer/Binder: Edwards Brothers Manufacturing Manager: Nick Sklitsis Cover Printer: Lehigh-Phoenix Color Operations Specialist: Lisa McDowell This book was composed in Quark. Basal font is Times. Display font is Berkeley. Copyright © 2013, 2010, 2008, 2005, 2003 by Pearson Education, Inc., publishing as Addison-Wesley. All rights reserved. Manufactured in the United States of America. This publication is protected by Copyright, and permission should be obtained from the pub- lisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or like- wise. To obtain permission(s) to use material from this work, please submit a written request to Pearson Education, Inc., Permissions Department, One Lake Street, Upper Saddle River, New Jersey 07458, or you may fax your request to 201-236-3290.
    [Show full text]
  • The Value of Repeatable Experiments and Negative Results
    The value of repeatable experiments and negative results Dave Täht Bufferbloat.net Sigcomm CCW th Aug 18 , 2014 Installing netperf-wrapper ● Linux (debian or ubuntu) – sudo apt-get install python-matplotlib python-qt4 fping subversion git-core – git clone https://github.com/tohojo/netperf-wrapper.git – cd netperf-wrapper; sudo python setup.py install – See the readme for other dependencies.(netperf needs to be compiled with –enable-demo) ● OSX – Requires macports or brew, roughly same sequence ● Data Set: http://snapon.lab.bufferbloat.net/~d/datasets/ ● This slide set: http://snapon.lab.bufferbloat.net/~d/sigcomm2014.pdf Bufferbloat.net Resources Reducing network delays since 2011... Bufferbloat.net: http://bufferbloat.net Email Lists: http://lists.bufferbloat.net (codel, bloat, cerowrt-devel, etc) IRC Channel: #bufferbloat on chat.freenode.net Codel: https://www.bufferbloat.net/projects/codel CeroWrt: http://www.bufferbloat.net/projects/cerowrt Other talks: http://mirrors.bufferbloat.net/Talks Jim Gettys Blog: http://gettys.wordpress.com Google for bloat-videos on youtube... Netperf-wrapper test suite: https://github.com/tohojo/netperf-wrapper “Reproducible” vs “Repeatable” Experiments ● Researcher MIGHT be ● Researcher MUST be easily able to repeat experiment repeat the experiment in in light of new data. light of new data. ● Reviewer SHOULD be able ● Reviewer typically lacks to re-run the experiment time to reproduce. and inspect the code. ● Reader MIGHT be able, ● Reader SHOULD be able from the descriptions in from the code and data the paper, reproduce the supplied by the research, result, by rewriting the repeat the experiment code from scratch. quickly and easily. What's wrong with reproducible? ● Coding errors are terribly ● You have 30 seconds to get common – code review is my attention.
    [Show full text]
  • ACM SIGARCH Order # Is 415972. IEEE Computer Society Press Order # Is RS00160
    ACM SIGARCH Order # is 415972. IEEE Computer Society Press Order # is RS00160. ISBN: 0-89791-985-8 Copies may be ordered from ACM Member Services: 1-800-342-6626 (U.S. and Canada) +1 212-626-0500 (Global) +1 212-944-1318 (Fax) Email: [email protected] Online: http://www.acm.org/catalog The SC97 Technical Program, presented Tuesday through Friday, November 18-21, includes both plenary and parallel sessions. The parallel sessions have been organized to ensure that topics of interest to a wide range of audiences are available during these times. The parallel tracks are divided into two components as follows: Presentations by authors of contributed papers. These represent the very best papers submitted to the conference. Each has been through a competitive peer review process and has been selected as an outstanding contribution. There will be a total of 57 technical papers presented at SC97. Topics of general interest in a wide variety of areas. Sessions will include invited talks on a variety of subjects, presented by an impressive array of experts, as well as panel discussions that are sure to engage attendees' interest. Tuesday, November 18 -- 10:30am-noon [Room B1] Communication in Clusters Session Chair: David Culler, University of California, Berkeley 1. The Effects of Communication Parameters on End Performance of Shared Virtual Memory Clusters Angelos Bilas, Jaswinder Pal Singh, Princeton University 2. FM-QoS: Real-time Communication Using Self-synchronizing Schedules Kay H. Connelly, Andrew A. Chien, University of Illinois at Urbana-Champaign 3. Multi-protocol Active Messages on a Cluster of SMPs Steven S.
    [Show full text]
  • The Evolution of Internet Congestion
    The Evolution of Internet Congestion Steven Bauer 1, David Clark 2, William Lehr 3 Massachusetts Institute of Technology Abstract This paper discusses the evolution of the congestion controls that govern all Internet traffic. In particular we chronicle and discuss the implications of the fact that the most significant "congestion signals" are increasingly coming from network operators, not the TCP stack. Providers now nudge users into different traffic patterns using a variety of new technical and non-technical means. These 'network-based congestion management' techniques include volume-based limits and active traffic management of best effort traffic. The goal and effect of these techniques differs from the historically coveted flow-rate fairness of TCP, provoking some in the technical and policy community to question the appropriateness of such deviations, and feeding debates over network management and network neutrality. To appropriately evaluate emerging trends in congestion control, it is useful to understand how congestion control has evolved in the Internet, both with respect to its intellectual history within the technical community and with respect to the changing traffic/industry environment in which the Internet operates. This is important because a sophisticated and nuanced view of congestion and its management is necessary for good public policy in this space. We conclude the paper with a discussion of the policy implications and questions raised by the continual evolution of congestion. 1. Introduction The phenomenal growth of the Internet in terms of the volume of economic activity and traffic it carries over the past fifty years represents a remarkable example of the scalability of the Internet architecture, which in spite of the growth, remains in many respects, fundamentally unchanged.
    [Show full text]
  • CS 640 Introduction to Computer Networks Today's Lecture
    CS 640 Introduction to Computer Networks Lecture 1 CS 640 Today’s lecture • Introduction to communication networks – Purpose – History – Underlying technologies • Fundamental problems – Reliability – Resource sharing, cooperation and competition – Structure, growth and evolution CS 640 Purpose of communication networks • Carrying messages from sender to receiver • Supporting conversations between people • Enabling access to sources of information • Dissemination of information • Simulating user’s presence at remote locations • Remote monitoring • The list keeps evolving CS 640 1 A brief history of the Internet • Leonard Kleinrock published work in ‘61 – Shows packet switching effective for bursty traffic • DARPA contract for BBN to build switches – First network had four nodes in ‘69 • Email first application – Ray Tomlinson, ’72 • In ’74 Vint Cerf and Robert Kahn developed open architecture for Internet (TCP and IP) • By ’79 the 200 nodes and by’89 over 100K! – Much growth fueled by connecting universities – Larry Landweber from UW had important role • In ’89 Van Jacobson made MAJOR improvements to TCP • In ’91 Tim Berners-Lee invented the Web • In ’93 Marc Andreesen invented Mosaic CS 640 Building Blocks • Nodes: PC, special-purpose hardware… – hosts (PCs, cell phones, toasters, etc.) – routers (and switches, bridges, hubs, etc.) • Links: coax cable, optical fiber, wireless … – point-to-point … – multiple access CS 640 Nodes and links form networks • A network can be defined recursively as... – two or more nodes – two or more networks
    [Show full text]
  • Protocol Layering and Internet Policy
    ARTICLE PROTOCOL LAYERING AND INTERNET POLICY CHRISTOPHER S. YOO† An architectural principle known as protocol layering is widely recognized as one of the foundations of the Internet’s success. In addition, some scholars and industry participants have urged using the layers model as a central organizing principle for regulatory policy. Despite its importance as a concept, a comprehensive analysis of protocol layering and its implications for Internet policy has yet to appear in the literature. This Article attempts to correct this omission. It begins with a detailed description of the way the five-layer model developed, introducing protocol layering’s central features, such as the division of functions across layers, infor- mation hiding, peer communication, and encapsulation. It then discusses the model’s implications for whether particular functions are performed at the edge or in the core of the network, contrasts the model with the way that layering has been depicted in the legal commentary, and analyzes attempts to use layering as a basis for competition policy. Next the Article identifies certain emerging features of the Internet that are placing pressure on the layered model, including WiFi routers, network-based security, modern routing protocols, and wireless broadband. These developments illustrate how every architecture inevitably limits functionality as well as the architecture’s ability to evolve over time in response to changes in the † John H. Chestnut Professor of Law, Communication, and Computer & Information Sci- ence and Founding Director of the Center for Technology, Innovation and Competition (CTIC), University of Pennsylvania. I would like to thank the Milton and Miriam Handler Foundation, the New York Bar Foundation, and CTIC for their financial support for this project.
    [Show full text]