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University of British Columbia CICS 515 (Part 1) Internet Computing Lecture 1 - Overview

University of British Columbia CICS 515 (Part 1) Internet Computing Lecture 1 - Overview. Instructor: Dr. Son T. Vuong Email: vuong@cs.ubc.ca May 8, 2012 The World Connected. Information and Organization. Instructor: Dr. Son Vuong Email: vuong@cs.ubc.ca

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University of British Columbia CICS 515 (Part 1) Internet Computing Lecture 1 - Overview

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  1. University of British ColumbiaCICS 515 (Part 1)Internet ComputingLecture 1 - Overview Instructor: Dr. Son T. Vuong Email: vuong@cs.ubc.ca May 8, 2012 The World Connected Introduction

  2. Information and Organization • Instructor: Dr. Son Vuong • Email: vuong@cs.ubc.ca • Office Hours: T, Th: 1:00-2:00pm (CS 329) • TA: • Jonatan Schroederjonatan@cs.ubc.ca • ShahedAlammalam@cs.ubc.ca • Lectures: T, Th: 11am-1 pm in DMP 110 • Lab: Th: 2-4 pm (CS 045/051) Introduction

  3. Text and Workload • Text:Computer Networking: A Top Down Approach Featuring the Internet, 6th edition. Jim Kurose, Keith Ross. Addison-Wesley, April 2012. • Course Load: • 2 Projects/Asgmts (20%) • 2 Quizzes (10%) • Midterm (25%) • Final exam (45%) • Bonus for class participation, BlueCT + Peerwise (4%) • Late penalty: 5*2i %, 0< i =< 3 (i = # days late) • Website:www.icics.ubc.ca/~cics515 • Vista: http://www.vista.ubc.ca/ (id=pwd=CWL) Introduction

  4. Revised CISC 515 Outline (Tentative) • (T - 08/5) Overview (Chapter 1) P1 • (Th - 10/5) Application Layer (The Web and HTTP) (Ch 2) • (T - 15/5) WebCache and Transport Layer (Ch 3) • (Th - 17/5) Transport Layer (Ch 3) • (T- 22/5) Transport Layer (TCP) (Ch 3) Quiz1 • (Th - 24/5) TCP Congestion (P1) P2 • (T-29/5) IP (Ch 4) IPv6 (Ch 4) Midterm • (Th - 31/6) Other Protocols (ICMP, DHCP, DNS), Routing (RIP, OSPF) (Ch 4) • (T - 05/6) Routing (RIP, OSPF, BGP) (Ch 4) • (Th- 07/6) Data Link protocols (Ethernet) (Ch 5) (P2) • (T- 12/6) Wireless Networks (WiFi) (Ch 6) Quiz2 • (Th-14/6) Review 13. (F-15/6) Final Exam Introduction

  5. Our goal: get context, overview, “feel” of networking more depth, detail later in course approach: descriptive use Internet as example Overview: what’s the Internet what’s a protocol? network edge network core access net, physical media Internet/ISP structure performance: loss, delay protocol layers, service models history Chapter 1: Introduction Introduction

  6. Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Protocol layers, service models 1.7 Delay & loss in packet-switched networks 1.8 History Introduction

  7. millions of connected computing devices: hosts, end-systems PCs workstations, servers PDAs phones, toasters running network apps communication links fiber, copper, radio, satellite transmission rate = bandwidth routers: forward packets (chunks of data) router workstation server mobile local ISP regional ISP company network What’s the Internet: “nuts and bolts” view Introduction

  8. “Cool” internet appliances IP picture frame http://www.ceiva.com/ Web-enabled toaster+weather forecaster World’s smallest web server http://www-ccs.cs.umass.edu/~shri/iPic.html Introduction

  9. protocolscontrol sending, receiving of msgs e.g., TCP, IP, HTTP, FTP, PPP Internet: “network of networks” loosely hierarchical public Internet versus private intranet Internet standards RFC: Request for comments IETF: Internet Engineering Task Force What’s the Internet: “nuts and bolts” view router workstation server mobile local ISP regional ISP company network Introduction

  10. communication infrastructure enables distributed applications: Web, email, games, e-commerce, database., voting, file (MP3) sharing communication services provided to apps: connectionless connection-oriented What’s the Internet: a service view • cyberspace [Gibson]: “a consensual hallucination experienced daily by billions of operators, in every nation, ...." Introduction

  11. Uses of Internet • Business Applications • Home Applications • Mobile Users • Social Issues Introduction

  12. Business Applications of Networks • A network with two clients and one server. Introduction

  13. Business Applications of Networks (2) • The client-server model involves requests and replies. Introduction

  14. Home Network Applications • Access to remote information • Person-to-person communication • Interactive entertainment • Electronic commerce Introduction

  15. Home Network Applications (2) • In peer-to-peer system there are no fixed clients and servers. Introduction

  16. Home Network Applications (3) • Some forms of e-commerce. Introduction

  17. Mobile Network Users • Combinations of wireless networks and mobile computing. Introduction

  18. Classification of Networks • Classification of interconnected processors by scale. Introduction

  19. Example Networks • The Internet • Connection-Oriented Networks: X.25, Frame Relay, and ATM • Ethernet • Wireless LANs: 802:11 (WiFi) Introduction

  20. Network Perspective • Network users: services that their applications need, e.g., guarantee that each message it sends will be delivered without error within a certain amount of time • Network designers: cost-effective design e.g., that network resources are efficiently utilized and fairly allocated to different users • Network providers: system that is easy to administer and manage e.g., that faults can be easily isolated and it is easy to account for usage Introduction

  21. Connectivity • Building Blocks • links: coax cable, optical fiber... • nodes: general-purpose workstations... • Direct Links • point-to-point • multiple access Introduction

  22. Switched Networks • A network can be defined recursively as: • two or more nodes connected by a physical link, • or by two or more networks connected by one or more nodes • Internetworks • Internet vs internet Introduction

  23. network edge: applications and hosts network core: routers network of networks access networks, physical media: communication links A closer look at network structure: Introduction

  24. Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Protocol layers, service models 1.7 Delay & loss in packet-switched networks 1.8 History Introduction

  25. end systems (hosts): run application programs e.g. Web, email at “edge of network” client/server model client host requests, receives service from always-on server e.g. Web browser/server; email client/server peer-peer model: minimal (or no) use of dedicated servers e.g. Gnutella, KaZaA The network edge: Introduction

  26. Goal: data transfer between end systems handshaking: setup (prepare for) data transfer ahead of time Hello, hello back human protocol set up “state” in two communicating hosts TCP - Transmission Control Protocol Internet’s connection-oriented service TCP service[RFC 793] reliable, in-order byte-stream data transfer loss: acknowledgements and retransmissions flow control: sender won’t overwhelm receiver congestion control: senders “slow down sending rate” when network congested Network edge: connection-oriented service Introduction

  27. Goal: data transfer between end systems same as before! UDP - User Datagram Protocol [RFC 768]: Internet’s connectionless service unreliable data transfer no flow control no congestion control App’s using TCP: HTTP (Web), FTP (file transfer), Telnet (remote login), SMTP (email) App’s using UDP: streaming media, teleconferencing, DNS, Internet telephony Network edge: connectionless service Introduction

  28. Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Protocol layers, service models 1.7 Delay & loss in packet-switched networks 1.8 History Introduction

  29. mesh of interconnected routers the fundamental question: how is data transferred through net? circuit switching: dedicated circuit per call: telephone net packet-switching: data sent thru net in discrete “chunks” The Network Core Introduction

  30. Switching Strategies • Circuit switching: dedicated circuit; send/receive a bit stream • original telephone network • Packet switching: store-and-forward; send/receive messages (packets) • Internet Introduction

  31. Switching Strategies (a) Circuit switching (b) Message switching (c) Packet switching Introduction

  32. Nodal delay • dproc = processing delay • typically a few microsecs or less • dqueue = queuing delay • depends on congestion • dtrans = transmission delay • = L/R, significant for low-speed links • dprop = propagation delay • a few microsecs to hundreds of msecs Introduction

  33. Great for bursty data resource sharing simpler, no call setup Excessive congestion: packet delay and loss protocols needed for reliable data transfer, congestion control Q: How to provide circuit-like behavior? bandwidth guarantees needed for audio/video apps still an unsolved problem (chapter 6) Is packet switching a “slam dunk winner?” Packet switching versus circuit switching Introduction

  34. Takes L/R seconds to transmit (push out) packet of L bits on to link or R bps Entire packet must arrive at router before it can be transmitted on next link: store and forward delay = 3L/R Example: L = 7.5 Mbits R = 1.5 Mbps delay = 3x 5 sec = 15 sec Packet-switching: store-and-forward L R R R Introduction

  35. Now break up the message into 5000 packets Packet Switching: Message Segmenting • Each packet 1,500 bits • 1 msec to transmit packet on one link • pipelining: each link works in parallel • Delay reduced from 15 sec to 5.002 sec Introduction

  36. Now assume the message/packets go through 2 additional switches (over the path of 4 switches) Packet Switching: Message Segmenting L R R R R • What is the total delay to send the message without breaking into packets (i.e. non-pipelining) ? • What is the total delay to send the message as 5000 packets (i.e. pipelining) ? Introduction

  37. Q 1.1  Peer Instruction packet switching Now assume the message/packets go through 2 additional switches (over the path of 4 switches) What is the total delay to send the message as 5000 packets (i.e. pipelining) ? Answer: (A) 25 s  (B) 15 s  (C) 5.002 s  (D) 5.004 s (E) None of the above Introduction

  38. Q 1.1  Peer Instruction packet switching Now assume the message/packets go through 2 additional switches (over the path of 4 switches) What is the total delay to send the message as 5000 packets (i.e. pipelining) ? Answer: (A) 25 s  (B) 15 s  (C) 5.002 s  (D) 5.004 s (E) None of the above Introduction

  39. Goal: move packets through routers from source to destination we’ll study several path selection (i.e. routing)algorithms (chapter 4) datagram network: destination address in packet determines next hop routes may change during session analogy: driving, asking directions virtual circuit network: each packet carries tag (virtual circuit ID), tag determines next hop fixed path determined at call setup time, remains fixed thru call routers maintainper-call state Packet-switched networks: forwarding Introduction

  40. Addressing and Routing • Address: byte-string that identifies a node • usually unique • Routing: how to forward messages towards the destination node based on its address • Types of addresses • unicast: node-specific • broadcast: all nodes on the network • multicast: some subset of nodes on the network Introduction

  41. L1 R1 L2 R2 Switch 1 Switch 2 L3 R3 Multiplexing • Time-Division Multiplexing (TDM) • Frequency-Division Multiplexing (FDM) Introduction

  42. Example: 4 users FDMA frequency time TDMA frequency time Circuit Switching: FDMA and TDMA Introduction

  43. Time Division Multiplexing (T1 Carrier) The T1 carrier (1.544 Mbps). (1 bit + 24 slots * 8 bits/slot) * 8000 frames/s = 193 bits/frame * 8000 frames/s =1.544 Mbps Introduction

  44. Peer Instruction 1.1 – T1 TDM Question • How long does it take to send a file of 640,000 bits from host A to host B over a (sub)channel (a circuit) in a T1 TDM based circuit-switched network? • Overall T1 TDM carrier capacity is 1.536 Mbps • Data transmission uses one of the 24 slots of the T1 carrier • 500 msec to establish end-to-end circuit Work it out! (A) 510 ms (B) 1500 ms (C) 2.5 s (D) 10.5 s (E) None of the above Introduction

  45. 1.1 Peer Instruction – T1 TDM Answer • How long does it take to send a file of 640,000 bits from host A to host B over a (sub)channel (a circuit) in a T1 TDM based circuit-switched network? • Overall TDM channel capacity is 1.536 Mbps (T1: 1.544 Mbps with 8Kbps framing) • Data transmission uses one of the 24 slots of the TDM channel • 500 msec = 0.5s to establish end-to-end circuit Answer: Each circuit= 1.536Mbps/24 = 64Kbps Tx(file) = 640Kb/64Kbps = 10s plus Tsetup (A) 510 ms (B) 1500 ms (C) 2.5 s (D)10.5 s (E) None of the above Introduction

  46. Peer Instruction 1.1 – T1 TDM Question • How long does it take to send a file of 640,000 bits from host A to host B over 5 (sub)channels (circuits) in a T1 TDM based circuit-switched network? • Overall T1 TDM carrier capacity is 1.536 Mbps • Data transmission uses one of the 24 slots of the T1 carrier • 500 msec to establish end-to-end circuit Work it out! (A) 510 ms (B) 1500 ms (C) 2.5 s (D) 10.5 s (E) None of the above Introduction

  47. 1.1 Peer Instruction – T1 TDM Answer • How long does it take to send a file of 640,000 bits from host A to host B over 5 (sub)channel (circuits) in a T1 TDM based circuit-switched network? • Overall TDM channel capacity is 1.536 Mbps (T1: 1.544 Mbps with 8Kbps framing) • Data transmission uses one of the 24 slots of the TDM channel • 500 msec = 0.5s to establish end-to-end circuit Answer: Each circuit= 1.536Mbps/24 = 64Kbps Tx(file) = 640Kb/(5x64Kbps) = 2splus Tsetup (A) 510 ms (B) 1500 ms (C) 2.5 s (D)10.5 s (E) None of the above Introduction

  48. … Statistical Multiplexing (ATDM) • On-demand time-division, rather than fixed (STDM) • Schedule link on a per-packet basis • Packets from different sources interleaved on link • Buffer packets that are contending for the link • Packet queue may be processed FIFO • Buffer (queue) overflow is called congestion ATDM or Concentrator Introduction

  49. Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Protocol layers, service models 1.7 Delay & loss in packet-switched networks 1.8 History Introduction

  50. Protocols • Building blocks of a network architecture • Each protocol object has two different interfaces: • service: operations on this protocol • peer-to-peer (protocol): messages exchanged with peer • Term “protocol” is overloaded • specification of peer-to-peer interface • module that implements this interface Introduction

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