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TOC: IntroductionNetwork ExamplesNetwork Components EthernetInterconnected LANsInternetworkTypes of NetworksInternetPacketsTransport

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Introduction: Network Examples

UCBBackbone: Teleglobe Global Crossing Williams

Regional: Palo AltoTypes of NetworksInternetPacketsTransport

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Network Examples: UCB

E1E2

E3

REGIONAL1st Floor Cory

2nd FloorCory

SODA

EVANS

BACKBONE

CAMPUS

LOCAL

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Network Examples: Backbone

Teleglobe Communications Corporation – Fiber + Satellite

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Network Examples: Backbone

Global Crossing Corporation

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Network Examples: Backbone

Williams Communications

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Network Examples: Regional

Palo Alto Network

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Introduction: 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

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Network Components: Links

Fibers

Cat5 UnshieldedTwisted Pairs

Coaxial Cable

Wireless

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Network Components: NIC

Ethernet Network Interface Card

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Network ComponentsTelephone Switch Large Router

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Introduction: EthernetEthernet is a Local Area Network (LAN)

• Architecture: Switch and/or Hub

• System View: Services

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Ethernet: ArchitectureSwitch and/or Hub:

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

Abstract view:

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Introduction: Interconnected LANsLANs interconnected by routers

LAN1

LAN2

LAN3Internet

R1R2

R3 R4

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

Subnet 1Subnet 2

ISP 2ISP 1

Example: Subnet 1 = network of LANs of previous

slideISP 1 = Sprint, ISP 2 = MCISubnet 2 = UCB network

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Introduction: Types of Network

Classification 1: Size, Information, Application

Classification 2: Use, Protocols, Technologies

Switching Broadcast vs. Switched Characteristics How to switch Taxonomy

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Types of Network: Classification 1

Geographical distance Local Area Networks (LAN): Ethernet, Token ring, FDDI Metropolitan Area Networks (MAN): DQDB, SMDS Wide Area Networks (WAN): X.25, ATM, frame relay Caveat: LAN, MAN, WAN may mean different

things: Service, network technology, networks

Information type Data networks vs. telecommunication networks

Application type Special purpose networks: airline reservation network,

banking network, credit card network, telephony, CATV General purpose network: Internet

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Types of Network: Classification 2

Right to usePrivate: enterprise networksPublic: telephony network, Internet

Protocols:Proprietary: SNA, AppleTalkOpen: IP

TechnologiesTerrestrial vs. satelliteWired vs. wireless

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Broadcast Network:

Types of Network: Broadcast vs. Switched

Switched Network:

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Broadcast One to all Examples: some LANs (Hub-Ethernet, 802.11) Problem: coordinate the access of all nodes

to the shared communication medium (Multiple Access Problem)

Switched One to subset Examples: 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

Types of Network: Characteristics

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

Types of Network: How to Switch?

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Based on the way in which the nodes exchange information:

Types of Network: Taxonomy

Switched Broadcast

Circuit PacketVirtual

CircuitTelephone MPLS

ATMFrame Relay

Sw.-EthernetInternet

Hub-EthernetCATV

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Introduction: The Internet

Overview Scale

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Internet: Overview

A global network of networks all using a common protocol (IP, the Internet Protocol) Focus of this class A challenge to understand: large scale (10’s of millions of users,

10’s of thousands of networks) heterogeneity, irregular topology,

decentralized management

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Internet: Scale

• Data from www.nw.com

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Introduction: Packets

IllustrationMain Ideas

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Packets: Illustration

A

B

B port 2

12

3A | B | ...

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Packets: 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

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Introduction: Transport

Acknowledgments Link Sharing

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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.

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Transport: 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