EECS 122“Communications

Networks”

Department of Electrical Engineering and Computer Sciences

Table of Contents1. Course Organization2. Introduction3. Applications/Design4. Architecture 15. Models6. Physical Layer7. Ethernet8. 802.119. IP: Network Layer10. Switching and Forwarding11. TCP/UDP: Transport Layer12. Flow and Congestion Control13. WWW/DNS; RTP; etc.14. Socket Programming15. Distributed Algorithms16. Network Security17. Overlay Networks and Peer-to-Peer Networks18. Sensor Networks19. Architecture 2

Course Logistics – SP2004� Instructors:

� Dr. Shyam Parekh: OH M 3-4, F 3-4, 463 Cory; shyam@eecs� Prof. Jean Walrand: OH Tu 11-12, W 2-3, 257M Cory; wlr@eecs

� TAs:� Rajarshi Gupta: OH Tu 2-3 (493 Cory)� Rishi Kant: OH TBA� John Musacchio: OH Th 1-2 (493 Cory)

� Course Manager:� Dr. Shyam Parekh; shyam@eecs

� Class Homepage:� http://walrandpc.eecs.berkeley.edu/122S04.html

� Discussion Sections:� Tu 1-2, 170 Barrows (Rajarshi Gupta)� W 10-11, 122 Wheeler – Cancelled, Please switch� W 4-5, 106 Moffit (Rishi Kant)� Th 11-12, 299 Cory (John Musacchio)

TOC - Logistics

Grading

� Final Exam (25%), Mid-term (15%)� Homework Assignments (25%) – 5 Assignments� Projects (35%)

� Socket Programming (1 Project – Weighted 2x)� OPNET Exercises (5 Assignments)

TOC - Logistics - grading

Projects

� Network Programming� Application of socket programming� Client/Server; Get and manage files; handle

errors

� OPNET� Study protocols through simulation experiments� OPNET environment provided;

Minimize learning curve

TOC - Logistics - Projects

Books� Required Textbook:

L. Peterson & B. Davie,Computer Networks: A Systems Approach, 3rd Ed.

� Other Useful Networking Texts:� A. Tanenbaum, Computer Networks� R. Stevens, TCP/IP Illustrated (vol 1)� S. Keshav, An Engineering Approach to

Computer Networking� Kurose and Ross, Computer Networking� Walrand, Communication Networks, 2nd Ed

TOC - Logistics - Books

Programming� This course will involve programming. Network

programming project will be implemented in C on either Windows or UNIX

� Your work can be done on your “named” account. If you lack one, you may log in as “newacct” on one of the clients listed below:

http://www-inst.eecs.berkeley.edu/clients

TOC - Logistics - Programming

Books on Programming

� S. Maguire, Writing Solid Code� S. Lippman, C++ Primer� R. Stevens, UNIX Network Programming,

Volume 1, 2nd ed.

TOC - Logistics – Books on Programming

IntroductionNetwork ExamplesNetwork Components EthernetInterconnected LANsInternetworkTypes of NetworksInternetPacketsTransport

TOC - Introduction

Network ExamplesUCBBackbone:

TeleglobeGlobal CrossingWilliams

Regional: Palo AltoTypes of NetworksInternetPacketsTransport

TOC - Introduction – Network Examples

UCB

E1E2

E3

REGIONAL1st Floor Cory

2nd FloorCory

SODA

EVANS

BACKBONE

LOCAL

CAMPUSTOC - Introduction – Network Examples - UCB

BackboneTeleglobe

TOC - Introduction – Network Examples – Backbone/Teleglobe

BackboneGlobal Crossing Corporation

TOC - Introduction – Network Examples – Backbone/Global Crossing

Backbone Williams Communications

TOC - Introduction – Network Examples – Backbone/Williams

Regional Palo Alto Network

TOC - Introduction – Network Examples – Regional/Palo Alto

Network Components

Links: carry bits from one place to another (or maybe to many other places)Interface: attaches device to linkSwitch/router: interconnect linksHost: communication endpoint (workstation, PDA, cell phone, toaster, tank) – connected to links

TOC - Introduction – Network Components

Links

Fibers

Cat5 UnshieldedTwisted Pairs

Wireless

Coaxial Cable

TOC - Introduction – Network Components - Links

Ethernet Network Interface Card

TOC - Introduction – Network Components - NIC

Telephone Switch Router

TOC - Introduction – Network Components – Switch & Router

Ethernet

Ethernet is a Local Area Network (LAN)

• Architecture: Switch and/or Hub

• System View: Services

TOC - Introduction – Ethernet

ArchitectureSwitch and/or Hub:

TOC - Introduction – Ethernet - Architecture

System View

Ethernet is a broadcast-capable, multi-access LANProvides a “Link” service between nodes

Abstract view:

TOC - Introduction – Ethernet – System View

Interconnected LANs

LANs interconnected by routers

LAN1

LAN3Internet

R1R2

R3 R4

LAN2

TOC - Introduction – Interconnected LANs

InternetworkProvides message delivery between multiple networks that may belong to different organizations:

Subnet 1

ISP 2ISP 1

Subnet 2

Example:Subnet 1 = network of LANs of previous slideISP 1 = Sprint, ISP 2 = MCISubnet 2 = UCB network

TOC - Introduction – Internetwork

Types of Network

Classification 1: Size, Information, ApplicationClassification 2: Use, Protocols, TechnologiesSwitching

Broadcast vs. SwitchedCharacteristicsHow to switchTaxonomy

TOC - Introduction – Types of Nework

Classification 1

Geographical distanceLocal Area Networks (LAN): Ethernet, Token ring, FDDIMetropolitan Area Networks (MAN): DQDB, SMDSWide Area Networks (WAN): X.25, ATM, frame relayCaveat: LAN, MAN, WAN may mean different things: Service, network technology, networks

Information typeData networks vs. telecommunication networks

Application typeSpecial purpose networks: airline reservation network, banking network, credit card network, telephony, CATVGeneral purpose network: Internet

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Classification 2

Right to usePrivate: enterprise networksPublic: telephony network, Internet

Protocols:Proprietary: SNA, AppleTalkOpen: IP

TechnologiesTerrestrial vs. satelliteWired vs. wireless

TOC - Introduction – Types of Nework – Classification 2

Broadcast vs. Switched

Broadcast Network:

Switched Network:

TOC - Introduction – Types of Nework – Switching – Broadcast vs. Switched

Characteristics

BroadcastOne to allExamples: some LANs (Hub-Ethernet, 802.11) Problem: coordinate the access of all nodes to the shared communication medium (Multiple Access Problem)

SwitchedOne to subsetExamples: WANs (Telephony Network, Internet)Problem: how to forward information to intended node(s)

This is done by special nodes (e.g., routers, switches) running routing protocols

TOC - Introduction – Types of Nework – Switching – Characteristics

How to Switch?

Circuit-Switched: 1. Set up circuit between two devices2. Exchange information3. Release circuit

Packet-Switched:Send packets with source and destination addresses

Vircuit-Circuit Switched:1. Select path from source to destination (Virtual

Circuit)2. Assign a “label” to that path3. Send packets with that label4. Release Virtual Circuit

{Note: Some VCs are permanent.}

TOC - Introduction – Types of Nework – Switching – How to Switch?

Based on the way in which the nodes exchange information:

Taxonomy

Switched Broadcast

Circuit PacketVirtualCircuit

Telephone MPLSATMFrame Relay

Sw.-EthernetInternet

Hub-EthernetCATV

TOC - Introduction – Types of Nework – Switching – Taxonomy

The InternetOverviewScale

TOC - Introduction – The Internet

OverviewA global network of networks all using a

common protocol (IP, the Internet Protocol)Focus of this classA challenge to understand:

large scale (10’s of millions of users, 10’s of thousands of networks)heterogeneity, irregular topology, decentralized management

TOC - Introduction – The Internet - Overview

Scale

• Data from www.nw.comTOC - Introduction – The Internet - Scale

Packets

IllustrationMain Ideas

TOC - Introduction – Packets

Illustration

A

B

B → port 2

12

3A | B | ...

TOC - Introduction – Packets - Illustration

Main Ideas

The switches have no memory of packets: scalabilityThe network is independent of the applications: flexibilityThe packet formats and addresses are independent of the technology: extensibility

TOC - Introduction – Packets – Main Ideas

Transport

AcknowledgmentsLink Sharing

TOC - Introduction – Transport

Acknowledgments

The destination sends back an acknowledgment for every correct packet it gets.The source uses these ACKs to- Retransmit unacknowledged packets- Adjust the rate of its transmissions.

The destination sends back an acknowledgment for every correct packet it gets.The source uses these ACKs to- Retransmit unacknowledged packets- Adjust the rate of its transmissions.

TOC - Introduction – Transport - Acknowledgments

Link SharingShared links

The sources base theirtransmissions on when they get acknowledgments.The scheme regulates the sharing of common links

The sources base theirtransmissions on when they get acknowledgments.The scheme regulates the sharing of common links

TOC - Introduction – Transport – Link Sharing