TOC : Introduction

1. TOC: Introduction • Network Examples • Network Components • Ethernet • Interconnected LANs • Internetwork • Types of Networks • Internet • Packets • Transport

2. Introduction: Network Examples • UCB • Backbone: • Teleglobe • Global Crossing • Williams • Regional: Palo Alto • Types of Networks • Internet • Packets • Transport

3. E3 E1 E2 Network Examples: UCB BACKBONE SODA 2nd Floor Cory 1st Floor Cory REGIONAL EVANS LOCAL CAMPUS

4. Network Examples: Backbone Teleglobe Communications Corporation – Fiber + Satellite

5. Network Examples: Backbone Global Crossing Corporation

6. Network Examples: Backbone Williams Communications

7. Network Examples: Regional Palo Alto Network

8. 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

9. Network Components: Links Fibers Cat5 Unshielded Twisted Pairs Coaxial Cable Wireless

10. Network Components: NIC Ethernet Network Interface Card

11. Network Components Telephone Switch Large Router

12. Introduction: Ethernet • Ethernet is a Local Area Network (LAN) • Architecture: Switch and/or Hub • System View: Services

13. Ethernet: Architecture Switch and/or Hub:

14. Ethernet: System View • Ethernet is a broadcast-capable, multi-access LAN • Provides a “Link” service between nodes • Abstract view:

15. Introduction: Interconnected LANs LANs interconnected by routers LAN2 LAN1 R1 R2 Internet LAN3 R4 R3

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

17. Introduction: Types of Network • Classification 1: Size, Information, Application • Classification 2: Use, Protocols, Technologies • Switching • Broadcast vs. Switched • Characteristics • How to switch • Taxonomy

18. 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

19. Types of Network: Classification 2 • Right to use • Private: enterprise networks • Public: telephony network, Internet • Protocols: • Proprietary: SNA, AppleTalk • Open: IP • Technologies • Terrestrial vs. satellite • Wired vs. wireless

20. Types of Network: Broadcast vs. Switched • Broadcast Network: Switched Network:

21. Types of Network: Characteristics • 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

22. Types of Network: How to Switch? Circuit-Switched: • Set up circuit between two devices • Exchange information • Release circuit • Packet-Switched: • Send packets with source and destination addresses • Vircuit-Circuit Switched: • 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.}

23. Switched Broadcast VirtualCircuit Circuit Packet Types of Network: Taxonomy • Based on the way in which the nodes exchange information: Hub-Ethernet CATV Telephone MPLS ATM Frame Relay Sw.-Ethernet Internet

24. Introduction: The Internet • Overview • Scale

25. 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

26. Internet: Scale • Data from www.nw.com

27. Introduction: Packets • Illustration • Main Ideas

28. B 1 2 3 A B  port 2 Packets: Illustration A | B | ...

29. 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

30. Introduction: Transport • Acknowledgments • Link Sharing

31. 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.

32. Shared links Transport: Link Sharing The sources base their transmissions on when they get acknowledgments. The scheme regulates the sharing of common links