ECE 358: Computer Networks. Homework #3. Chapter 5 and 6 Review Questions 1

Size: px
Start display at page:

Download "ECE 358: Computer Networks. Homework #3. Chapter 5 and 6 Review Questions 1"

Transcription

1 ECE 358: Computer Networks Homework #3 Chapter 5 and 6 Review Questions 1 Chapter 5: The Link Layer P26. Let's consider the operation of a learning switch in the context of a network in which 6 nodes labeled A through F are star connected into an Ethernet switch. Suppose that (i) B sends a frame to E, (ii) E replies with a frame to B, (iii) A sends a frame to B, (iv) B replies with a frame to A. The switch table is initially empty. Show the state of the switch table before and after each of these events. For each of these events, identify the link(s) on which the transmitted frame will be forwarded, and briefly justify your answers. : Action Switch Table State Link(s) packet is forwarded to Explanation B sends a frame to E Switch learns interface MAC address of B A, C, D, E, and F Since switch table is empty, so switch does not know the interface MAC address of E E replies with a frame to B Switch learns interface MAC address of E B Since switch already knows interface MAC address of B A sends a frame to B Switch learns the interface MAC address of A B Since switch already knows the interface MAC address of B B replies with a frame to A Switch table state remains the same as before A Since switch already knows the interface MAC address of A 1 From the textbook (Computer Networking: A Top- Down Approach, 6 Th edition) Pages 508, 579 & 581

2 P27. In this problem, we explore the use of small packets for Voice-over IP applications. One of the drawbacks of a small packet size is that a large fraction of link bandwidth is consumed by overhead bytes. To this end, suppose that the packet consists of L bytes and 5 bytes of header. a. Consider sending a digitally encoded voice source directly. Suppose the source is encoded at a constant rate of 128 kbps. Assume each packet is entirely filled before the source sends the packet into the network. The time required to fill a packet is the packetization delay. In terms of L, determine the packetization delay in milliseconds. b. Packetization delays greater than 20 msec. can cause a noticeable and unpleasant echo. Determine the packetization delay for L = 1,500 bytes (roughly corresponding to a maximumsized Ethernet packet) and for L = 50 (corresponding to an ATM packet). c. Calculate the store-and-forward delay at a single switch for a link rate of R = 622 Mbps for L=1,500 bytes, and for L = 50 bytes. d. Comment on the advantages of using a small packet size. a) The time required to fill L 8 bits is L L sec = 16 3 m sec. b) For L = 1,500, the packetization delay is 1500 m sec = 93.75msec. 16 For L = 50, the packetization delay is 50 m sec = 3.125msec. 16 c) Store-and-forward delay For L = 1, 500, the delay is sec 19.4µ sec L = R

3 For L = 50, store-and-forward delay < 1µ sec. d) Store-and-forward delay is small for both cases for typical link speeds. However, packetization delay for L = 1500 is too large for real-time voice applications. Chapter 6: Wireless Networks R6. True or false: Before an station transmits a data frame; it must first send an RTS frame and receive a corresponding CTS frame. False R10. Suppose the IEEE RTS and CTS frames were as long as the standard DATA and ACK frames. Would there be any advantage to using the CTS and RTS frames? Why or why not? No, there wouldn t be any advantage. Suppose there are two stations that want to transmit at the same time, and they both use RTS/CTS. If the RTS frame is as long as a DATA frames, the channel would be wasted for as long as it would have been wasted for two colliding DATA frames. Thus, the RTS/CTS exchange is only useful when the RTS/CTS frames are significantly smaller than the DATA frames. P7. Suppose an b station is configured to always reserve the channel with the RTS/CTS sequence. Suppose this station suddenly wants to transmit 1,000 bytes of data, and all other stations are idle at this time. As a function of SIFS and DIFS, and ignoring propagation delay and assuming no bit errors, calculate the time required to transmit the frame and receive the acknowledgment.

4 A frame without data is 32 bytes long. Assuming a transmission rate of 11 Mbps, the time to transmit a control frame (such as an RTS frame, a CTS frame, or an ACK frame) is (256 bits)/(11 Mbps) = 23 usec. The time required to transmit the data frame is (8256 bits)/(11 Mbps) = 751 DIFS + RTS + SIFS + CTS + SIFS + FRAME + SIFS + ACK = DIFS + 3SIFS + (3* ) usec = DIFS + 3SIFS usec Selected questions from previous midterms 1. In this part of the question, all stations use the IEEE MAC protocol, DIFS = 130 µs and aslot = 50 µs. Assume that, while in the DCF mode of operation, station A generates a random value 12 for its BTC (Back-off Time Counter) at time instant t1. The carrier sensing mechanism of station A detects the medium to be busy/free as follows: - Busy for 400 µs from instant t1. - Free for 300 µs after the previous busy period. - Busy for 1000 µs after the previous free period. - Free for long enough for BTC to expire at some time instant t2. Compute the actual time gap between t2 and t1. Only the last period X (free for long enough until BTC=0) is unknown. Δ= t 2 -t 1 = ( X)µs DIFS: Distributed InterFrame Spaces; the medium needs to be idle for this period of time, before station can start transmitting. BTC: once medium is sensed to be idle for DIFS, BTC is decreased by one, then the medium is sensed again after an aslot period. Every time, i.e. after an aslot period, the medium is sensed to be idle, the counter is decremented. Station starts transmitting once medium is idle and BTC=0 t2- t1 = DIFS + 9*aSlot = 2280

5 300µs 400µs DIFS 1000µs DIFS t1 BTC= Three important time intervals in the operation of the IEEE MAC protocol are DIFS, SIFS, and PIFS. - State the desired relationship among the three intervals, and explain where and why those intervals are used. - Explain the consequence(s) of a faulty protocol implementation where PIFS > DIFS. Relation: SIFS<PIFS<DIFS SIFS (Short Inter Frame Spacing): Is the smallest interval; gives the highest priority to on-going communications. Separates RTS, CTS, DATA, ACK. The ACK or RTS are sent after SIFS and before PIFS. PIFS (Point Inter Frame Spacing): The second priority goes to Access Point. It gives the Access Point (working in PCF mode) a chance to grab the control of the channel. Access Point can either starts transmitting to the desired station or gives the permission to desired stations to communicate. PIFS>SIFS, to detect an on-going transmission. DIFS (Distributed Inter Frame Spacing): Third (lowest) priority. After this interval all the stations, in DCF mode, start competing for the channel. DIFS>SIFS, to detect an on-going transmission. DIFS>PIFS, to give the priority to Access Point (see part 2). If PIFS>DIFS, stations in DCF mode have higher priority than Access Point. The Access Point can only grab the channel when no other station wants to transmit anything. It may take a long time before Access Point is being able to grab the control of the channel.

6 3. In the IEEE standard, explain the function and operation of the Network Allocation Vector (Be sure to use a diagram to help in your explanation). In DCF mode, A sender obtains permission from the intended receiver before transmitting a packet by sending a Request to Send (RTS) packet The receiver granting permission by transmitting a Clear To Send (CTS) packet Stations other than the two communicating hearing either RTS or CTS will lock themselves out of the channel for a period of time this is the Network Allocation Vector NAV this process is also called virtual carrier sense The objective is to provide collision avoidance or reduce the number of collisions (but preventing other stations from transmitting) It is important to note that stations may be within range of only one of the two communicating parties so they respond differently to the RTS and CTS messages.

CSMA/CA. Information Networks p. 1

CSMA/CA. Information Networks p. 1 Information Networks p. 1 CSMA/CA IEEE 802.11 standard for WLAN defines a distributed coordination function (DCF) for sharing access to the medium based on the CSMA/CA protocol Collision detection is not

More information

Wiereless LAN 802.11

Wiereless LAN 802.11 Tomasz Kurzawa Wiereless LAN 802.11 Introduction The 802.11 Architecture Channels and Associations The 802.11 MAC Protocol The 802.11 Frame Introduction Wireless LANs are most important access networks

More information

802.11 standard. Acknowledgement: Slides borrowed from Richard Y. Yang @ Yale

802.11 standard. Acknowledgement: Slides borrowed from Richard Y. Yang @ Yale 802.11 standard Acknowledgement: Slides borrowed from Richard Y. Yang @ Yale IEEE 802.11 Requirements Design for small coverage (e.g. office, home) Low/no mobility High data-rate applications Ability to

More information

... neither PCF nor CA used in practice

... neither PCF nor CA used in practice IEEE 802.11 MAC CSMA/CA with exponential backoff almost like CSMA/CD drop CD CSMA with explicit ACK frame added optional feature: CA (collision avoidance) Two modes for MAC operation: Distributed coordination

More information

Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - III

Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - III Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - III CS: 647 Advanced Topics in Wireless Networks Drs. Baruch Awerbuch & Amitabh Mishra Department of Computer Science Johns Hopkins

More information

802.11 Wireless LAN Protocol CS 571 Fall 2006. 2006 Kenneth L. Calvert All rights reserved

802.11 Wireless LAN Protocol CS 571 Fall 2006. 2006 Kenneth L. Calvert All rights reserved 802.11 Wireless LAN Protocol CS 571 Fall 2006 2006 Kenneth L. Calvert All rights reserved Wireless Channel Considerations Stations may move Changing propagation delays, signal strengths, etc. "Non-transitive"

More information

LAN Switching. 15-441 Computer Networking. Switched Network Advantages. Hubs (more) Hubs. Bridges/Switches, 802.11, PPP. Interconnecting LANs

LAN Switching. 15-441 Computer Networking. Switched Network Advantages. Hubs (more) Hubs. Bridges/Switches, 802.11, PPP. Interconnecting LANs LAN Switching 15-441 Computer Networking Bridges/Switches, 802.11, PPP Extend reach of a single shared medium Connect two or more segments by copying data frames between them Switches only copy data when

More information

Attenuation (amplitude of the wave loses strength thereby the signal power) Refraction Reflection Shadowing Scattering Diffraction

Attenuation (amplitude of the wave loses strength thereby the signal power) Refraction Reflection Shadowing Scattering Diffraction Wireless Physical Layer Q1. Is it possible to transmit a digital signal, e.g., coded as square wave as used inside a computer, using radio transmission without any loss? Why? It is not possible to transmit

More information

CSE 123: Computer Networks

CSE 123: Computer Networks CSE 123: Computer Networks Homework 2 Out: 4/20, Due: 4/27 Instructions 1. Turn in a physical copy at the beginning of the class on 4/27 2. Ensure the HW cover page has the following information clearly

More information

17.4 IEEE MEDIUM ACCESS CONTROL

17.4 IEEE MEDIUM ACCESS CONTROL 17.4 / IEEE 802.11 MEDIUM ACCESS CONTROL 535 refers to a wired LAN that is physically connected to the DS and whose stations may be logically connected to an IEEE 802.11 LAN via the integration service.

More information

ECE 428 Computer Networks and Security

ECE 428 Computer Networks and Security ECE 428 Computer Networks and Security 1 Instructor: Sagar Naik About the Instructor Office: EIT 4174, ECE Dept. Other courses that I teach ECE 355: Software Engineering ECE 453/CS 447/ SE 465: Software

More information

Announcements : Wireless Networks Lecture 9: MAC. Outline. History. Page 1

Announcements : Wireless Networks Lecture 9: MAC. Outline. History. Page 1 Announcements 18-759: Wireless Networks Lecture 9: 80.11 Peter Steenkiste Departments of Computer Science and Electrical and Computer Engineering Spring Semester 016 http://www.cs.cmu.edu/~prs/wirelesss16/

More information

Second Midterm for ECE374 04/23/12 Solution!!

Second Midterm for ECE374 04/23/12 Solution!! 1 Second Midterm for ECE374 04/23/12 Solution!! Instructions: Put your name and student number on each sheet of paper! The exam is closed book. You have 90 minutes to complete the exam. Be a smart exam

More information

Ethernet. Outline Multiple Access and Ethernet Intro Ethernet Framing CSMA/CD protocol Exponential backoff

Ethernet. Outline Multiple Access and Ethernet Intro Ethernet Framing CSMA/CD protocol Exponential backoff Ethernet Outline Multiple Access and Ethernet Intro Ethernet Framing CSMA/CD protocol Exponential backoff Our Focus is Ethernet History Developed by Bob Metcalfe and others at Xerox PARC in mid-1970s Roots

More information

Medium Access Sublayer

Medium Access Sublayer Medium Access Sublayer Topology of the Network Bus, Ring, Tree Protocols IEEE 802.3 for bus topology IEEE 802.4 for token bus IEEE 802.5 for token ring FDDI for fibre ring IEEE 802.11 for wireless networks

More information

VoIP in 802.11. Mika Nupponen. S-72.333 Postgraduate Course in Radio Communications 06/04/2004 1

VoIP in 802.11. Mika Nupponen. S-72.333 Postgraduate Course in Radio Communications 06/04/2004 1 VoIP in 802.11 Mika Nupponen S-72.333 Postgraduate Course in Radio Communications 06/04/2004 1 Contents Introduction VoIP & WLAN Admission Control for VoIP Traffic in WLAN Voice services in IEEE 802.11

More information

CS/ECE 438: Communication Networks for Computers Spring 2014 Midterm Study Guide

CS/ECE 438: Communication Networks for Computers Spring 2014 Midterm Study Guide CS/ECE 438: Communication Networks for Computers Spring 2014 Midterm Study Guide 1. Channel Rates and Shared Media You are entrusted with the design of a network to interconnect a set of geographically

More information

CSE 123: Computer Networks

CSE 123: Computer Networks Total Points = 28 CSE 123: Computer Networks Homework 2 Solutions Out: 4/20, Due: 4/27 Problems 1. High Frequency Trading [5 pts] Companies like Goldman Sachs put a high value on using very low latency

More information

802.11. Markku Renfors. Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak

802.11. Markku Renfors. Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak 802.11 Markku Renfors Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak Contents 802.11 Overview & Architecture 802.11 MAC 802.11 Overview and Architecture

More information

Based on Computer Networking, 4 th Edition by Kurose and Ross

Based on Computer Networking, 4 th Edition by Kurose and Ross Computer Networks Ethernet Hubs and Switches Based on Computer Networking, 4 th Edition by Kurose and Ross Ethernet dominant wired LAN technology: cheap $20 for NIC first widely used LAN technology Simpler,

More information

WLAN (802.11) Nomadic Communications. Renato Lo Cigno - Tel: 2026. Dipartimento di Ingegneria e Scienza dell Informazione

WLAN (802.11) Nomadic Communications. Renato Lo Cigno - Tel: 2026. Dipartimento di Ingegneria e Scienza dell Informazione Nomadic Communications WLAN (802.11) Renato Lo Cigno LoCigno@disi.unitn.it - Tel: 2026 Dipartimento di Ingegneria e Scienza dell Informazione Home Page: http://isi.unitn.it/locigno/index.php/teaching-duties/nomadic-communications

More information

(cont d.), Mobile IP, WAP

(cont d.), Mobile IP, WAP College of Computer Science Lecture 11 Northeastern University October 20th 2008 Wireless Networks CS G250 Lecturer: R. Sundaram 1 802.11 802.11 (cont d.), Mobile IP, WAP 1.1 The OSI and IEEE models Any

More information

IEEE 802 LANs. LAN: Local Area Network What is a local area network?

IEEE 802 LANs. LAN: Local Area Network What is a local area network? IEEE 802 LANs LAN: Local Area Network What is a local area network? A LAN is a network that resides in a geographically restricted area LANs usually span a building or a campus 1 Characteristics of LANs

More information

Collision of wireless signals. The MAC layer in wireless networks. Wireless MAC protocols classification. Evolutionary perspective of distributed MAC

Collision of wireless signals. The MAC layer in wireless networks. Wireless MAC protocols classification. Evolutionary perspective of distributed MAC The MAC layer in wireless networks The wireless MAC layer roles Access control to shared channel(s) Natural broadcast of wireless transmission Collision of signal: a /space problem Who transmits when?

More information

CS6956: Wireless and Mobile Networks Lecture Notes: 2/11/2015. IEEE 802.11 Wireless Local Area Networks (WLANs)

CS6956: Wireless and Mobile Networks Lecture Notes: 2/11/2015. IEEE 802.11 Wireless Local Area Networks (WLANs) CS6956: Wireless and Mobile Networks Lecture Notes: //05 IEEE 80. Wireless Local Area Networks (WLANs) CSMA/CD Carrier Sense Multi Access/Collision Detection detects collision and retransmits, no acknowledgement,

More information

Introduction to Local Area Networks

Introduction to Local Area Networks For Summer Training on Computer Networking visit Introduction to Local Area Networks Prepared by : Swapan Purkait Director Nettech Private Limited swapan@nettech.in + 91 93315 90003 Introduction A local

More information

IEEE 802.11 Technical Tutorial. Introduction. IEEE 802.11 Architecture

IEEE 802.11 Technical Tutorial. Introduction. IEEE 802.11 Architecture IEEE 802.11 Technical Tutorial Introduction The purpose of this document is to give technical readers a basic overview of the new 802.11 Standard, enabling them to understand the basic concepts, principle

More information

6.1. Why do LANs tend to use broadcast networks? Why not use networks consisting of multiplexers and switches?

6.1. Why do LANs tend to use broadcast networks? Why not use networks consisting of multiplexers and switches? TUTORIAL 2 (EKT 332) 6.1. Why do LANs tend to use broadcast networks? Why not use networks consisting of multiplexers and switches? Why broadcast network? -The computers in a LAN are separated by a short

More information

Ethernet, , Networking. CS158a Chris Pollett Mar 21, 2007.

Ethernet, , Networking. CS158a Chris Pollett Mar 21, 2007. Ethernet, 802.11, Networking CS158a Chris Pollett Mar 21, 2007. Outline Ethernet Performance Other types of Ethernet 802.11 Data Link Layer Switching Ethernet Performance To rigorously analyze the exponential

More information

WiFi. Is for Wireless Fidelity Or IEEE 802.11 Standard By Greg Goldman. WiFi 1

WiFi. Is for Wireless Fidelity Or IEEE 802.11 Standard By Greg Goldman. WiFi 1 WiFi Is for Wireless Fidelity Or IEEE 802.11 Standard By Greg Goldman WiFi 1 What is the goal of 802.11 standard? To develop a Medium Access Control (MAC) and Physical Layer (PHY) specification for wireless

More information

An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e

An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e Jahanzeb Farooq, Bilal Rauf Department of Computing Science Umeå University Sweden Jahanzeb Farooq, 2006 (tipputhegreat@hotmail.com) Chapter

More information

ECE 333: Introduction to Communication Networks Fall 2001

ECE 333: Introduction to Communication Networks Fall 2001 ECE 333: Introduction to Communication Networks Fall 2001 Lecture 17: Medium Access Control V Perfectly scheduled approaches Token ring networks 1 We have categorized channel allocation techniques as either

More information

06/02/ Local & Metropolitan Area Networks. Overview. Medium Access Sublayer (1) ACOE322

06/02/ Local & Metropolitan Area Networks. Overview. Medium Access Sublayer (1) ACOE322 1 Local & Metropolitan Area Networks ACOE322 Lecture 2 Medium Access Control and Logical Link Control 1 Overview The architecture of a LAN is best described in terms of a layering of protocols that organize

More information

RTT 60.5 msec receiver window size: 32 KB

RTT 60.5 msec receiver window size: 32 KB Real-World ARQ Performance: TCP Ex.: Purdue UCSD Purdue (NSL): web server UCSD: web client traceroute to planetlab3.ucsd.edu (132.239.17.226), 30 hops max, 40 byte packets 1 switch-lwsn2133-z1r11 (128.10.27.250)

More information

CS 5480/6480: Computer Networks Spring 2012 Homework 4 Solutions Due by 1:25 PM on April 11 th 2012

CS 5480/6480: Computer Networks Spring 2012 Homework 4 Solutions Due by 1:25 PM on April 11 th 2012 CS 5480/6480: Computer Networks Spring 2012 Homework 4 Solutions Due by 1:25 PM on April 11 th 2012 Important: The solutions to the homework problems from the course book have been provided by the authors.

More information

4. MAC protocols and LANs

4. MAC protocols and LANs 4. MAC protocols and LANs 1 Outline MAC protocols and sublayers, LANs: Ethernet, Token ring and Token bus Logic Link Control (LLC) sublayer protocol Bridges: transparent (spanning tree), source routing

More information

A Technical Tutorial on the IEEE 802.11 Protocol

A Technical Tutorial on the IEEE 802.11 Protocol A Technical Tutorial on the IEEE 802.11 Protocol By Pablo Brenner Director of Engineering copyright BreezeCOM 1997 Introduction The purpose of this document is to give technical readers a basic overview

More information

Inst: Chris Davison

Inst: Chris Davison ICS 153 Introduction to Computer Networks Inst: Chris Davison cbdaviso@uci.edu ICS 153 Introduction to Computer Networks MAC Sublayer Contents Fixed Assignment Protocols Demand Assignment Protocols Contention

More information

Local Area Networks (LANs)

Local Area Networks (LANs) Local Area Networks (LANs) Broadcast Networks Multiple Access Protocols Ethernet (IEEE 802.3) Token Ring (IEEE 802.5, FDDI) Introduction So far, we have dealt with switched communication networks. Recall

More information

LANs. Local Area Networks. via the Media Access Control (MAC) SubLayer. Networks: Local Area Networks

LANs. Local Area Networks. via the Media Access Control (MAC) SubLayer. Networks: Local Area Networks LANs Local Area Networks via the Media Access Control (MAC) SubLayer 1 Local Area Networks Aloha Slotted Aloha CSMA (non-persistent, 1-persistent, p-persistent) CSMA/CD Ethernet Token Ring 2 Network Layer

More information

Local & Metropolitan Area Networks

Local & Metropolitan Area Networks Local & Metropolitan Area Networks CS455 Yonshik Choi, Ph.D. Department of Computer Science Illinois Institute of Technology Rice Campus Local Area Networks Characteristic Smaller geographical area a

More information

Basic processes in IEEE802.11 networks

Basic processes in IEEE802.11 networks Module contents IEEE 802.11 Terminology IEEE 802.11 MAC Frames Basic processes in IEEE802.11 networks Configuration parameters.11 Architect. 1 IEEE 802.11 Terminology Station (STA) Architecture: Device

More information

Link Layer Standards and Protocols

Link Layer Standards and Protocols Link Layer Standards and Protocols Link Layer Standards IP Layer (Network Layer) LLC IEEE 802.2 MAC IEEE 802.X Physical Layer Medium Access Control Layer Services Concerned with the following Channel allocation

More information

Ethernet. Ethernet Frame Structure. Ethernet Frame Structure (more) Ethernet: uses CSMA/CD

Ethernet. Ethernet Frame Structure. Ethernet Frame Structure (more) Ethernet: uses CSMA/CD Ethernet dominant LAN technology: cheap -- $20 for 100Mbs! first widely used LAN technology Simpler, cheaper than token rings and ATM Kept up with speed race: 10, 100, 1000 Mbps Metcalfe s Etheret sketch

More information

Philippe Klein. avb-phkl-802-11-qos-overview-0811-1

Philippe Klein. avb-phkl-802-11-qos-overview-0811-1 802.11 QoS Overview Philippe Klein IEEE Plenary Meeting Nov 08 Dallas, TX avb-phkl-802-11-qos-overview-0811-1 Disclaimer This presentation is not a highly detailed technical presentation but a crash course

More information

Second Midterm for ECE374 04/16/12 Solution!!

Second Midterm for ECE374 04/16/12 Solution!! ECE374: Second Midterm 1 Second Midterm for ECE374 04/16/12 Solution!! Instructions: Put your name and student number on each sheet of paper! The exam is closed book. You have 90 minutes to complete the

More information

New York University Computer Science Department Courant Institute of Mathematical Sciences

New York University Computer Science Department Courant Institute of Mathematical Sciences ew York University Computer Science Department Courant Institute of Mathematical Sciences Course Title: Data Communication & etworks Course umber: g22.2662-00 Instructor: Jean-Claude Franchitti Session:

More information

CSE331: Introduction to Networks and Security Homework 1 Fall 2006 Due: 29 Sept. 2006

CSE331: Introduction to Networks and Security Homework 1 Fall 2006 Due: 29 Sept. 2006 CSE331: Introduction to Networks and Security Homework 1 Fall 006 Due: 9 Sept. 006 What to turn in: Submit hardcopy answers to the questions below. Please include your name, e-mail address, and the number

More information

Nov doc.: IEEE / aa QoS Tutorial. Date: Authors: Submission. Graham Smith, DSP Group

Nov doc.: IEEE / aa QoS Tutorial. Date: Authors: Submission. Graham Smith, DSP Group Authors: 802.11 QoS Tutorial Date: 2008-11-10 Slide 1 Abstract The channel access schemes for 802.11 are outlined and the two QoS schemes, introduce in 802.11e, described in more detail. The major differences

More information

TCP in Wireless Networks

TCP in Wireless Networks Outline Lecture 10 TCP Performance and QoS in Wireless s TCP Performance in wireless networks TCP performance in asymmetric networks WAP Kurose-Ross: Chapter 3, 6.8 On-line: TCP over Wireless Systems Problems

More information

EXAMPLES AND PROBLEMS. Competence Based Education Internet Protocols

EXAMPLES AND PROBLEMS. Competence Based Education Internet Protocols EXAMPLES AND PROBLEMS Competence Based Education Internet Protocols Example 1 In following figure frames are generated at node A and sent to node C through node B. Determine the minimum transmission rate

More information

Telecommunication Systems

Telecommunication Systems PUF-HCM Master Informatics Telecommunication Systems RTEL 1 Team teaching Responsible Team: Email Rami Langar Rami Langar (Courses) Su Tam Nguyen (TD) Rami.Langar@lip6.fr guitar1911@yahoo.com RTEL 2 Organisation

More information

Chapter 7 Low-Speed Wireless Local Area Networks

Chapter 7 Low-Speed Wireless Local Area Networks Wireless# Guide to Wireless Communications 7-1 Chapter 7 Low-Speed Wireless Local Area Networks At a Glance Instructor s Manual Table of Contents Overview Objectives s Quick Quizzes Class Discussion Topics

More information

Tutorial for Chapter 1

Tutorial for Chapter 1 Tutorial for Chapter 1 CEN 444 Computer Networks Dr. Mostafa Dahshan Department of Computer Engineering College of Computer and Information Sciences King Saud University mdahshan@ksu.edu.sa Tutorial for

More information

Enhanced TXOP scheme for efficiency improvement of WLAN IEEE 802.11e

Enhanced TXOP scheme for efficiency improvement of WLAN IEEE 802.11e Enhanced TXOP scheme for efficiency improvement of WLAN IEEE 802.11e Jakub Majkowski, Ferran Casadevall Palacio Dept. of Signal Theory and Communications Universitat Politècnica de Catalunya (UPC) C/ Jordi

More information

MEDIA ACCESS CONTROL

MEDIA ACCESS CONTROL MEDIA ACCESS CONTROL Random Access & Token Rings 18 The Data Link Layer Simplest way to create a network of nodes Ø Connect the nodes directly with a physical medium Point-to-point links: Ø Choice of Media

More information

Final for ECE374 05/06/13 Solution!!

Final for ECE374 05/06/13 Solution!! 1 Final for ECE374 05/06/13 Solution!! Instructions: Put your name and student number on each sheet of paper! The exam is closed book. You have 90 minutes to complete the exam. Be a smart exam taker -

More information

Star topology. Ethernet. Ethernet Frame Structure (more) Ethernet Frame Structure. Ethernet uses CSMA/CD. Unreliable, connectionless service

Star topology. Ethernet. Ethernet Frame Structure (more) Ethernet Frame Structure. Ethernet uses CSMA/CD. Unreliable, connectionless service thernet dominant wired LN technology: cheap $0 for 00Mbs! first widely used LN technology Simpler, cheaper than token LNs and TM Kept up with speed race: 0 Mbps 0 bps Star topology us topology popular

More information

Tutorial Questions EG/ES The tutorial questions illustrate the style of examination questions for EG/ES 3567.

Tutorial Questions EG/ES The tutorial questions illustrate the style of examination questions for EG/ES 3567. The tutorial questions illustrate the style of examination questions for EG/ES 3567. The paper will be of 3 hours duration, and each student should attempt four questions during this time. You should aim

More information

Note! The problem set consists of two parts: Part I: The problem specifications pages Part II: The answer pages

Note! The problem set consists of two parts: Part I: The problem specifications pages Part II: The answer pages Part I: The problem specifications NTNU The Norwegian University of Science and Technology Department of Telematics Note! The problem set consists of two parts: Part I: The problem specifications pages

More information

USN 06EC71 Seventh Semester D.E. Degree Examination, December 2010 Computer Communication Networks Time: 3 hrs. Note: Answer any FIVE full questions, selecting at least TWO questions/rom each part. Max.

More information

Mobile Communications Exercise: Satellite Systems and Wireless LANs. Georg von Zengen, IBR, TU Braunschweig, www.ibr.cs.tu-bs.de

Mobile Communications Exercise: Satellite Systems and Wireless LANs. Georg von Zengen, IBR, TU Braunschweig, www.ibr.cs.tu-bs.de Mobile Communications Exercise: Satellite Systems and Wireless LANs N 1 Please define the terms inclination and elevation using the following two figures. How do these parameters influence the usefulness

More information

Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks

Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks 1 Mr. Praveen S Patil, 2 Mr. Rabinarayan Panda, 3 Mr. Sunil Kumar R D 1,2,3 Asst. Professor, Department of MCA, The Oxford College of Engineering,

More information

Rohit Sharma SUSCET, Tangori, Mohali, Punjab, India

Rohit Sharma SUSCET, Tangori, Mohali, Punjab, India ISSN : 2229-4333(Print) ISSN : 976-8491(Online) Simulator to Analyze QoS for /a/g standards Rohit Sharma SUSCET, Tangori, Mohali, Punjab, India E-mail : rohit9299@yahoo.com IJCST Vo l. 1, Is s u e 2, De

More information

ISSN: 2319-5967 ISO 9001:2008 Certified International Journal of Engineering Science and Innovative Technology (IJESIT) Volume 2, Issue 5, September

ISSN: 2319-5967 ISO 9001:2008 Certified International Journal of Engineering Science and Innovative Technology (IJESIT) Volume 2, Issue 5, September Analysis and Implementation of IEEE 802.11 MAC Protocol for Wireless Sensor Networks Urmila A. Patil, Smita V. Modi, Suma B.J. Associate Professor, Student, Student Abstract: Energy Consumption in Wireless

More information

Token Passing: IEEE802.5 standard. IEEE802.5 standard

Token Passing: IEEE802.5 standard. IEEE802.5 standard Token Passing: IEEE802.5 standard. 4 Mbps. maximum token holding time: 10 ms, limiting packet length. packet (token, data) format:. SD, ED mark start, end of packet 1 IEEE802.5 standard. AC access control

More information

An Experimental Study of Throughput for UDP and VoIP Traffic in IEEE 802.11b Networks

An Experimental Study of Throughput for UDP and VoIP Traffic in IEEE 802.11b Networks An Experimental Study of Throughput for UDP and VoIP Traffic in IEEE 82.11b Networks Sachin Garg sgarg@avaya.com Avaya Labs Research Basking Ridge, NJ USA Martin Kappes mkappes@avaya.com Avaya Labs Research

More information

MAC Addresses and ARP. Mac Addressing, Ethernet, and Interconnections. LAN Addresses and ARP. LAN Address (more) ARP protocol: Same LAN (network)

MAC Addresses and ARP. Mac Addressing, Ethernet, and Interconnections. LAN Addresses and ARP. LAN Address (more) ARP protocol: Same LAN (network) M ddresses and RP Mac ddressing, thernet, and Interconnections 32-bit IP address: network-layer address used to get datagram to destination IP subnet M (or LN or physical or thernet) address: used to get

More information

Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh

Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh, Ph.D. benveniste@ieee.org Mesh 2008, Cap Esterel, France 1 Abstract Abundant hidden node collisions and correlated channel access

More information

IEEE 802.11 Wireless LAN Standard. Updated: 5/10/2011

IEEE 802.11 Wireless LAN Standard. Updated: 5/10/2011 IEEE 802.11 Wireless LAN Standard Updated: 5/10/2011 IEEE 802.11 History and Enhancements o 802.11 is dedicated to WLAN o The group started in 1990 o First standard that received industry support was 802.11b

More information

WAN Data Link Protocols

WAN Data Link Protocols WAN Data Link Protocols In addition to Physical layer devices, WANs require Data Link layer protocols to establish the link across the communication line from the sending to the receiving device. 1 Data

More information

CS413: Computer Networks

CS413: Computer Networks CS413: Computer Networks 2005 Fall Term Midterm Exam Solution Student ID: Name: Problem No. Marks Your Marks 1 16 2 5 3 5 4 7 5 4 6 7 7 3 8 3 Total 50 1 [Marking schemes are given in blue color and the

More information

11/22/2013 1. komwut@siit

11/22/2013 1. komwut@siit 11/22/2013 1 Week3-4 Point-to-Point, LAN, WAN Review 11/22/2013 2 What will you learn? Representatives for Point-to-Point Network LAN Wired Ethernet Wireless Ethernet WAN ATM (Asynchronous Transfer Mode)

More information

Computer Networks Homework 1

Computer Networks Homework 1 Computer Networks Homework 1 Reference Solution 1. (15%) Suppose users share a 1 Mbps link. Also suppose each user requires 100 kbps when transmitting, but each user transmits only 10 percent of the time.

More information

How does IEEE fit into ISO OSI-7 layer model? Existing IEEE LAN standards. Access to physical medium. model?

How does IEEE fit into ISO OSI-7 layer model? Existing IEEE LAN standards. Access to physical medium. model? Existing IEEE LAN standards slide 1 slide 2 How does IEEE fit into ISO OSI-7 layer model? the standards produced by IEEE in LANs have widely been adopted by industry the 802 committee have become internationally

More information

Improving Throughput Performance of the IEEE 802.11 MAC Layer Using Congestion Control Methods

Improving Throughput Performance of the IEEE 802.11 MAC Layer Using Congestion Control Methods Improving Throughput Performance of the IEEE 802.11 MAC Layer Using Congestion Control Methods Song Ci CS Department University of Michigan-Flint Flint, MI48502 cisong@umich.edu Guevara Noubir College

More information

A Comparative Study of MAC Layer Protocols for Mobile Ad-Hoc Networks

A Comparative Study of MAC Layer Protocols for Mobile Ad-Hoc Networks International Journal of Information and Computation Technology. ISSN 0974-2239 Volume 4, Number 4 (2014), pp. 351-362 International Research Publications House http://www. irphouse.com /ijict.htm A Comparative

More information

Random Access Protocols

Random Access Protocols Lecture Today slotted vs unslotted ALOHA Carrier sensing multiple access Ethernet DataLink Layer 1 Random Access Protocols When node has packet to send transmit at full channel data rate R. no a priori

More information

IEEE 802.11e WLANs / WMM. S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd.

IEEE 802.11e WLANs / WMM. S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd. IEEE 802.11e WLANs / WMM S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd. Outline A short review of 802.11 MAC Drawbacks of 802.11 MAC Application

More information

A Real-Time Multimedia Streaming Protocol for Wireless Networks

A Real-Time Multimedia Streaming Protocol for Wireless Networks 1 A Real-Time Multimedia Streaming Protocol for Wireless Networks Hans Scholten, Pierre Jansen, Ferdy Hanssen, Wietse Mank and Arjan Zwikker University of Twente, Department of Computer Science (EEMCS),

More information

Networks. Master of Science (Computer Science and Engineering), December 2004, 45 pp.,

Networks. Master of Science (Computer Science and Engineering), December 2004, 45 pp., Park, Sangtae, Optimal Access Point Selection and Channel Assignment in IEEE 802.11 Networks. Master of Science (Computer Science and Engineering), December 2004, 45 pp., 9 tables, 17 figures, 29 titles.

More information

Performance Analysis of the IEEE 802.11 Wireless LAN Standard 1

Performance Analysis of the IEEE 802.11 Wireless LAN Standard 1 Performance Analysis of the IEEE. Wireless LAN Standard C. Sweet Performance Analysis of the IEEE. Wireless LAN Standard Craig Sweet and Deepinder Sidhu Maryland Center for Telecommunications Research

More information

Railway Freight Dispatching Telephone System Based on VoIP in Wireless Networks

Railway Freight Dispatching Telephone System Based on VoIP in Wireless Networks International Conference on Computer, Communications and Information Technology (CCIT 2014) Railway Freight Dispatching Telephone System Based on VoIP in Wireless Networks Jun Xiao1, Feng Liu1, 2 1 2 School

More information

CSE331: Introduction to Networks and Security. Lecture 6 Fall 2006

CSE331: Introduction to Networks and Security. Lecture 6 Fall 2006 CSE331: Introduction to Networks and Security Lecture 6 Fall 2006 Open Systems Interconnection (OSI) End Host Application Reference model not actual implementation. Transmits messages (e.g. FTP or HTTP)

More information

Can I add a VoIP call?

Can I add a VoIP call? Can I add a VoIP call? Sachin Garg Avaya Labs Basking Ridge, NJ 07920 Email: sgarg@avaya.com Martin Kappes Avaya Labs Basking Ridge, NJ 07920 Email: mkappes@avaya.com Abstract In this paper, we study the

More information

Chapter 2 Network Devices

Chapter 2 Network Devices Chapter 2 Network Devices Objectives Explain the uses, advantages, and disadvantages of repeaters, hubs, wireless access points, bridges, switches, and routers Define the standards associated with wireless

More information

Circuit vs. Packet Switching

Circuit vs. Packet Switching Circuit vs. Packet Switching 1 Taxonomy of Switched Wide Area Networks WAN Telecommunication Systems intelligent core dumb nodes Circuit-Switched Networks (e.g. telephone networks) dumb core intelligent

More information

Video Transmission over Wireless LAN. Hang Liu Hang.liu@thomson.net

Video Transmission over Wireless LAN. Hang Liu Hang.liu@thomson.net Video Transmission over Wireless LAN Hang Liu Hang.liu@thomson.net Page 1 Introduction! Introduction! Wi-Fi Multimedia and IEEE 802.11e for QoS Enhancement! Error Control Techniques Page 2 Introduction!

More information

Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - I

Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - I Medium Access Control (MAC) Protocols for Ad hoc Wireless Networks - I CS: 647 Advanced Topics in Wireless Networks Drs. Baruch Awerbuch & Amitabh Mishra Department of Computer Science Johns Hopkins University

More information

Introduction to LAN Protocols

Introduction to LAN Protocols CHAPTER 2 Chapter Goals Learn about different LAN protocols. Understand the different methods used to deal with media contention. Learn about different LAN topologies. This chapter introduces the various

More information

Point-to-Point Vs. Shared Channel Communication In LANs Point-to-point:

Point-to-Point Vs. Shared Channel Communication In LANs Point-to-point: Point-to-Point Vs. Shared Channel Communication In LANs Point-to-point: Computers connected by communication channels that each connect exactly two computers with access to full channel bandwidth. Forms

More information

A TCP-like Adaptive Contention Window Scheme for WLAN

A TCP-like Adaptive Contention Window Scheme for WLAN A TCP-like Adaptive Contention Window Scheme for WLAN Qixiang Pang, Soung Chang Liew, Jack Y. B. Lee, Department of Information Engineering The Chinese University of Hong Kong Hong Kong S.-H. Gary Chan

More information

EEC-484/584 Computer Networks

EEC-484/584 Computer Networks EEC-484/584 Computer Networks Lecture 8 wenbing@ieee.org (Lecture nodes are based on materials supplied by Dr. Louise Moser at UCSB and Prentice-Hall) Outline 2 Homework #1 Review Protocol verification

More information

Communication Networks. MAP-TELE 2011/12 José Ruela

Communication Networks. MAP-TELE 2011/12 José Ruela Communication Networks MAP-TELE 2011/12 José Ruela Network basic mechanisms Multiple Access Multiple Access In early data communication systems, one solution to provide access of remote terminals to a

More information

Circuit Switching and Packet Switching

Circuit Switching and Packet Switching Chapter 9: Circuit Switching and Packet Switching CS420/520 Axel Krings Page 1 Switching Networks Long distance transmission is typically done over a network of switched nodes Nodes not concerned with

More information

LAN. Kent State University Dept. of Computer Science. CS 4/55231 Internet Engineering. LAN Topologies-1. Disadvantage. Advantages LECT-4A4

LAN. Kent State University Dept. of Computer Science. CS 4/55231 Internet Engineering. LAN Topologies-1. Disadvantage. Advantages LECT-4A4 CS 4/55231 Internet Engineering Kent State University Dept. of Computer Science LECT-4A4 LAN 1 2 In the last class we saw how two computers can connect to each other. In this class we will see how a group

More information

DATA COMMUNICATIONS AND NETWORKING. Solved Examples

DATA COMMUNICATIONS AND NETWORKING. Solved Examples Page 1 of 10 DATA COMMUNICATIONS AND NETWORKING Solved Examples References: STA: Stallings, Data and Computer Communications, 6 th ed. TAN: Tannenbaum, Computer Networks, 4 th ed.) 1. Given the following

More information

EECS 122: Introduction to Computer Networks Multiaccess Protocols. ISO OSI Reference Model for Layers

EECS 122: Introduction to Computer Networks Multiaccess Protocols. ISO OSI Reference Model for Layers EECS 122: Introduction to Computer Networks Multiaccess Protocols Computer Science Division Department of Electrical Engineering and Computer Sciences University of California, Berkeley Berkeley, CA 94720-1776

More information

CSE 3461: Introduction to Computer Networking and Internet Technologies. Packet Switching. Presentation G

CSE 3461: Introduction to Computer Networking and Internet Technologies. Packet Switching. Presentation G CSE 3461: Introduction to Computer Networking and Internet Technologies Packet Switching Presentation G Study: 10.5, 10.6, 12.1, 12.2, 13.1, 13.2, 18.3, 18.4 Gojko Babić 10-09-2012 The Network Core mesh

More information

Not all Ethernet standards utilize CSMA/CD MAC, the most commonly used 3 Ethernet Standards that support shared transmission medium are:

Not all Ethernet standards utilize CSMA/CD MAC, the most commonly used 3 Ethernet Standards that support shared transmission medium are: Ethernet is a family of computer networking technologies for LANs. Typical Ethernet standards (e.g. IEEE 802.3) model the Physical and Data Link Layers of OSI/RM. Not all Ethernet standards utilize CSMA/CD

More information