TOC Introduction Network Examples Network Components Ethernet Interconnected

TOC: Introduction Network Examples Network Components Ethernet Interconnected LANs Internetwork Types of Networks Internet Packets Transport EECS 122 - UCB 13

Introduction: Network Examples UCB Backbone: n n n Teleglobe Global Crossing Williams Regional: Palo Alto Types of Networks Internet Packets Transport EECS 122 - UCB 14

Network Examples: UCB SODA E 3 BACKBONE 2 nd Floor Cory E 1 E 2 1 st Floor Cory REGIONAL LOCAL EECS 122 - UCB CAMPUS EVANS 15

Network Examples: Backbone Teleglobe Communications Corporation – Fiber + Satellite EECS 122 - UCB 16

Network Examples: Backbone Global Crossing Corporation EECS 122 - UCB 17

Network Examples: Backbone Williams Communications EECS 122 - UCB 18

Network Examples: Regional Palo Alto Network EECS 122 - UCB 19

Introduction: Network Components Links: carry bits from one place to another (or maybe to many other places) Interface: attaches device to link Switch/router: interconnect links Host: communication endpoint (workstation, PDA, cell phone, toaster, tank) – connected to links EECS 122 - UCB 20

Network Components: Links Fibers Cat 5 Unshielded Twisted Pairs Coaxial Cable Wireless EECS 122 - UCB 21

Network Components: NIC Ethernet Network Interface Card EECS 122 - UCB 22

Network Components Telephone Switch EECS 122 - UCB Large Router 23

Introduction: Ethernet is a Local Area Network (LAN) • Architecture: Switch and/or Hub • System View: Services EECS 122 - UCB 24

Ethernet: Architecture Switch and/or Hub: EECS 122 - UCB 25

Ethernet: System View Ethernet is a broadcast-capable, multi-access LAN Provides a “Link” service between nodes Abstract view: EECS 122 - UCB 26

Introduction: Interconnected LANs interconnected by routers LAN 2 LAN 1 R 1 LAN 3 EECS 122 - UCB R 3 R 2 R 4 Internet 27

Introduction: Internetwork Provides message delivery between multiple networks that may belong to different organizations: ISP 1 Subnet 1 ISP 2 Subnet 2 Example: Subnet 1 = network of LANs of previous slide ISP 1 = Sprint, ISP 2 = MCI Subnet 2 = UCB network EECS 122 - UCB 28

Introduction: Types of Network Classification 1: Size, Information, Application Classification 2: Use, Protocols, Technologies Switching Broadcast vs. Switched n Characteristics n How to switch n Taxonomy n EECS 122 - UCB 29

Types of Network: Classification 1 Geographical distance n Local Area Networks (LAN): Ethernet, Token ring, FDDI Metropolitan Area Networks (MAN): DQDB, SMDS n Wide Area Networks (WAN): X. 25, ATM, frame relay n Caveat: LAN, MAN, WAN may mean different things: Service, network technology, networks n Information type n Data networks vs. telecommunication networks Application type n Special purpose networks: airline reservation n General purpose network: Internet network, banking network, credit card network, telephony, CATV EECS 122 - UCB 30

Types of Network: Classification 2 Right to use Private: enterprise networks n Public: telephony network, Internet n Protocols: Proprietary: SNA, Apple. Talk n Open: IP n Technologies Terrestrial vs. satellite n Wired vs. wireless n EECS 122 - UCB 31

Types of Network: Broadcast vs. Switched Broadcast Network: Switched Network: EECS 122 - UCB 32

Types of Network: Characteristics Broadcast n n n 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 n n n One to subset Examples: WANs (Telephony Network, Internet) Problem: how to forward information to intended node(s) w This is done by special nodes (e. g. , routers, switches) running routing protocols EECS 122 - UCB 33

Types of Network: How to Switch? Circuit-Switched: 1. 2. 3. Set up circuit between two devices Exchange information Release circuit Packet-Switched: n Send packets with source and destination addresses Vircuit-Circuit Switched: 1. 2. 3. 4. Select path from source to destination (Virtual Circuit) Assign a “label” to that path Send packets with that label Release Virtual Circuit {Note: Some VCs are permanent. } EECS 122 - UCB 34

Types of Network: Taxonomy Based on the way in which the nodes exchange information: Switched Circuit Telephone EECS 122 - UCB Virtual Circuit MPLS ATM Frame Relay Broadcast Packet Sw. -Ethernet Internet Hub-Ethernet CATV 35

Introduction: The Internet Overview Scale EECS 122 - UCB 36

Internet: Overview A global network of networks all using a common protocol (IP, the Internet Protocol) Focus of this class A challenge to understand: n n large scale (10’s of millions of users, 10’s of thousands of networks) heterogeneity, irregular topology, decentralized management EECS 122 - UCB 37

Internet: Scale • Data from www. nw. com EECS 122 - UCB 38

Introduction: Packets Illustration Main Ideas EECS 122 - UCB 39

Packets: Illustration B 1 A | B |. . . 2 3 A B port 2 EECS 122 - UCB 40

Packets: Main Ideas The switches have no memory of packets: scalability The network is independent of the applications: flexibility The packet formats and addresses are independent of the technology: extensibility EECS 122 - UCB 41

Introduction: Transport Acknowledgments Link Sharing EECS 122 - UCB 42

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. EECS 122 - UCB 43

Transport: Link Sharing Shared links The sources base their transmissions on when they get acknowledgments. The scheme regulates the sharing of common links EECS 122 - UCB 44