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EECS122 - UCB 1
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