CCM 4300 Lecture 5 Computer Networks, Wireless and Mobile Communications. Dr Shahedur Rahman. Room: T115

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "CCM 4300 Lecture 5 Computer Networks, Wireless and Mobile Communications. Dr Shahedur Rahman. Room: T115"

Transcription

1 CCM 4300 Lecture 5 Computer Networks, Wireless and Mobile Communications Dr Shahedur Rahman Room: T115 1

2 Recap of Last Session Described the physical layer Analogue and Digital signal bandwidth and throughput Transmission medium - Twisted pair, Coaxial cabling and optical fiber Described the data link layer Explained Basic definitions Media Access Control CSMA/CD, Token Passing 2

3 Session Content ALOHA, FDMA/TDMA/CDMA OSI Model/Internetworking Repeater, hub, switches, bridges, router 3

4 Lesson objectives At the completion of this lesson you should be able to : - describe the operation of ALOHA, FDMA, TDMA, CDMA - understand interconnection devices, mechanisms, and their operations. 4

5 Pure (unslotted) ALOHA Norman Abramson surfing & packet switching unslotted Aloha: simpler, no synchronization pkt needs transmission: - send without awaiting for beginning of slot collision probability increases: - pkt sent at t 0 collide with other pkts sent in [t 0-1, t 0 +1] If collision occurs transmit after different time intervals 5

6 Slotted Aloha time is divided into equal size slots (= pkt trans. time) node with new arriving pkt: transmit at beginning of next slot if collision: retransmit pkt in future slots with probability p, until successful. decentralized independently decides when to transmit but needs synchronization Success (S), Collision (C), Empty (E) slots 6

7 Recap: Pure/Slotted ALOHA Pure ALOHA access protocol - Data from remote terminals to the central computer site share a common transmission medium, a uhf radio channel. - Any terminals with data to transmit simply sends a packet. Hence there are occasional collisions. Slotted ALOHA access protocol - Similar to pure ALOHA except that packet transmission occurs only in agreed time slot - This doubles the maximum throughput compared to pure ALOHA, because a collision occupies no more than one time slot 7

8 Recap.. Cont. Nodes decision to transmit is made independent of the activity of the other nodes attached to the broadcast channel Nodes neither pays attention to whether another node begins transmitting nor stops transmission if another node begins to interfere with transmission 8

9 Channel Partitioning MAC protocols What is multiplexing? A mux (acronym for multiplexer) enables data of multiple transmission channels to share a common link. In Its simplest form, multiplexing involves combining data from several relatively low-speed input channels and transmitting these across a single high-speed circuit. Which layer of the OSI does multiplexing occurs? Layer 1 - Physical Layer 9

10 Network Core: Circuit Switching Capacity of medium exceeds the capacity required for transmission of a single signal How can we improve efficiency? Let s multiplex! Divide link bandwidth into pieces : frequency division - FDMA time division TDMA 10

11 Channel Partitioning MAC protocols: TDM TDM: time division multiplexing access to channel in "rounds" each station gets fixed length slot (length = pkt trans time) in each round unused slots go idle example: 6-station LAN, 1,3,4 have pkt, slots 2,5,6 idle 11

12 Channel Partitioning MAC protocols: FDM FDM: frequency division multiplexing channel spectrum divided into frequency bands each station assigned fixed frequency band unused transmission time in frequency bands go idle example: 6-station LAN, 1,3,4 have pkt, frequency bands 2,5,6 idle frequency bands 12

13 Example: FDMA and TDMA FDMA Example: 4 users frequency TDMA time frequency time 13

14 Advantages / Disadvantages Advantages - eliminates collision - perfectly fair; each node gets dedicated transmission Disadvantages - node is limited to average rate even when it is the only node with frames to send - node must always wait for its turn in transmission sequence even when it is the only node with a frame to send only for TDM 14

15 Channel Partitioning (CDMA) CDMA (Code Division Multiple Access) unique code assigned to each user; ie, code set partitioning used mostly in wireless broadcast channels (cellular, satellite,etc) all users share same frequency, but each user has own chipping sequence (ie, code) to encode data encoded signal = (original data) X (chipping sequence) decoding: inner-product of encoded signal and chipping sequence allows multiple users to coexist and transmit simultaneously with minimal interference (if codes are orthogonal ) 15

16 OSI Reference Model 16

17 Internetworking? We defined a network as a collection of computers and other devices. Collection of computer networks or network of networks are called an internetwork or internet Individual networks comprising an internetwork are called subnetworks Devices that interconnect subnetworks are called intermediate nodes (or intermediate systems) An internetwork can involve - local networks (e.g. LAN-to-LAN or LAN-tomainframe) - long-distance connections (e.g. LAN-to-WAN) - WAN-to-WAN connections 17

18 Internetwork (LAN-to-LAN) Intermediate Nodes router Subnetwork 1 Subnetwork 2 Network cloud consisting of many intermediate nodes 18

19 Network hardware devices Repeaters / Hubs Simplest level of interconnection, operating at the bottom layer of OSI (Layer 1) Suitable if: - both sides of the interconnection are identical - essentially repeaters operating at bit levels - the requirement is simply to repeat and boost all the digital signal transmission across similar media Some repeaters also provide re-timing capabilities A Multiport Repeater is called a Hub 19

20 Repeaters / Hubs - cont The performance of a repeater does not impact upon the network or its access techniques - e.g. if the network operates at 10Mbps, so does the repeater Repeaters operate at the bit level - typically introduces a few bits delay whilst the signal is boosted Media access techniques operate across the extended network as if it were a single cable - e.g the repeater does not separate CSMA/CD access techniques on either side of it 20

21 IWUs (Inter Working Unit) Repeaters Simple two-way amplifiers. Distance limitation in local-area networks Electrical signal becomes weaker as it travels Imposes a limit on the length of a LAN Clean up, amplify, and pass on bits. Used to extend the length of LANs. Functionality at the physical layer of the OSI framework. Media dependent and protocol independent Normally confined to a single building. Repeater 21

22 IWUs Repeaters (2) They provide no traffic isolation. They generally provide no network monitoring tools, you will not want to use repeaters for a link that is likely to fail. Maximum 4 Repeaters between source and destination (Ethernet). 22

23 Simple Repeater Operates at a very low level. Its primary purpose is to get around limitations in cable length. Passes on individual bits in the signal (even collisions), without doing any processing at the packet level. Note: The basic Ethernet design requires that signals must be able to get from one end of the network to the other within a specified amount of time. This determines a maximum allowable length. 23

24 Buffered Repeater Operates at the level of whole data packets. It receives an entire packet from one network into an internal buffer and then retransmits it onto the other network. Because such low-level features, as collisions are not repeated, the two networks continue to be separate as far as the Ethernet specifications are concerned. Thus there are no restrictions on the number of buffered repeaters that can be used. 24

25 Hubs Multi-port repeaters. Generally speaking, the term hub is used instead of repeater when referring to the device that serves as the centre of a star topology network Repeaters and Hubs have the following limitations Aggregate throughput is limited (Each bit is sent everywhere) Cannot support multiple LAN technologies Limitations on maximum nodes and distances 25

26 Bridges / Switches Link Layer (Layer 2) devices Designed to connect IEEE 802.x LANs together and provide a relay service at the MAC layer Bridge: Store and Forward - nodes connected to bridges share bandwidth Switch (multiport bridge): Store and Forward or Cut Through - Full-duplex (switching matrix / switch port assigned MAC address) - they have private connections Bridges learn which hosts can be reached through which interface: maintains filtering tables - when frame received, bridge learns location of sender by adding sender location in filtering table 26

27 Bridges Store and transmit packets. Functionality at DLL so media dependent and protocol independent above the DL layer. It is possible to use more repeaters by using switches. 16

28 Bridges (2) Bridges can determine whether the destination MAC address carried by data is a part of the same network segment as its source. It makes no determination as to what network segmentthedatashouldbesentto. Bridges indiscriminately pass data along to all other segments of the network. This may cause broadcast storms. Switch: Multi-port bridge. 28

29 Bridge Learning: example Suppose C sends frame to D and D replies back with frame to C C sends frame, bridge has no information about D, so floods to both LANs bridge notes that C is on port 1 frame ignored on upper LAN frame received by D C 1 entry added 29

30 Bridge Learning: example - cont D generates reply to C, sends it bridge sees frame from D bridge notes that D is on interface 2 C 1 D 2 entry added bridge knows C on interface 1, so selectively forwards frame out via interface 1 30

31 Routers Network Layer (Layer 3) devices - address used to route data (i.e. internet address) WAN is clearly beyond the LAN s domain - used to interconnect two or more administratively separate networks - each network can be set up and operated without knowledge of the other Routers are concerned with addressing 31

32 Routers - cont Stores information about the whole network, not just about a particular device Default gateway is used to decrease the size of routing table Different from hardware address used in bridging Disadvantages: - high cost - high latency of the device router has to analyse Layer 3 information 32

33 Summary ALOHA, other random access protocols OSI ref model and Internetworking Interconnection devices Repeater Hub Switches Bridges Router 33

Topics. Link Layer Services (more) Link Layer Services LECTURE 5 MULTIPLE ACCESS AND LOCAL AREA NETWORKS. flow control: error detection:

Topics. Link Layer Services (more) Link Layer Services LECTURE 5 MULTIPLE ACCESS AND LOCAL AREA NETWORKS. flow control: error detection: 1 Topics 2 LECTURE 5 MULTIPLE ACCESS AND LOCAL AREA NETWORKS Multiple access: CSMA/CD, CSMA/CA, token passing, channelization LAN: characteristics, i basic principles i Protocol architecture Topologies

More information

ECE 4450:427/527 - Computer Networks Spring 2017

ECE 4450:427/527 - Computer Networks Spring 2017 ECE 4450:427/527 - Computer Networks Spring 2017 Dr. Nghi Tran Department of Electrical & Computer Engineering Lecture 5.4: Multiple Access Protocols Dr. Nghi Tran (ECE-University of Akron) ECE 4450:427/527

More information

CS 43: Computer Networks Media Access. Kevin Webb Swarthmore College November 30, 2017

CS 43: Computer Networks Media Access. Kevin Webb Swarthmore College November 30, 2017 CS 43: Computer Networks Media Access Kevin Webb Swarthmore College November 30, 2017 Multiple Access Links & Protocols Two classes of links : point-to-point dial-up access link between Ethernet switch,

More information

Multiple-access protocols

Multiple-access protocols Multiple Access Multiple-access protocols Random Access MA CSMA CSMA/CD CSMA/CA RANDOM ACCESS In a random access method, each station has the right to the medium without being controlled by any other station.

More information

Internetworking is connecting two or more computer networks with some sort of routing device to exchange traffic back and forth, and guide traffic on

Internetworking is connecting two or more computer networks with some sort of routing device to exchange traffic back and forth, and guide traffic on CBCN4103 Internetworking is connecting two or more computer networks with some sort of routing device to exchange traffic back and forth, and guide traffic on the correct path across the complete network

More information

RMIT University. Data Communication and Net-Centric Computing COSC 1111/2061/1110. Lecture 8. Medium Access Control Methods & LAN

RMIT University. Data Communication and Net-Centric Computing COSC 1111/2061/1110. Lecture 8. Medium Access Control Methods & LAN RMIT University Data Communication and Net-Centric Computing COSC 1111/2061/1110 Medium Access Control Methods & LAN Technology Slide 1 Lecture Overview During this lecture, we will Look at several Multiple

More information

Lecture 5 The Data Link Layer. Antonio Cianfrani DIET Department Networking Group netlab.uniroma1.it

Lecture 5 The Data Link Layer. Antonio Cianfrani DIET Department Networking Group netlab.uniroma1.it Lecture 5 The Data Link Layer Antonio Cianfrani DIET Department Networking Group netlab.uniroma1.it Link Layer: setting the context two physically connected devices: host-router, router-router, host-host,

More information

CH : 15 LOCAL AREA NETWORK OVERVIEW

CH : 15 LOCAL AREA NETWORK OVERVIEW CH : 15 LOCAL AREA NETWORK OVERVIEW P. 447 LAN (Local Area Network) A LAN consists of a shared transmission medium and a set of hardware and software for interfacing devices to the medium and regulating

More information

Medium Access Protocols

Medium Access Protocols Medium Access Protocols Summary of MAC protocols What do you do with a shared media? Channel Partitioning, by time, frequency or code Time Division,Code Division, Frequency Division Random partitioning

More information

More on LANS. LAN Wiring, Interface

More on LANS. LAN Wiring, Interface More on LANS Chapters 10-11 LAN Wiring, Interface Mostly covered this material already NIC = Network Interface Card Separate processor, buffers incoming/outgoing data CPU might not be able to keep up network

More information

Local Area Network Overview

Local Area Network Overview Local Area Network Overview Chapter 15 CS420/520 Axel Krings Page 1 LAN Applications (1) Personal computer LANs Low cost Limited data rate Back end networks Interconnecting large systems (mainframes and

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

Medium Access Control

Medium Access Control Medium Access Control Mark Handley UCL Computer Science CS 3035/GZ01 Context: OSI Layer 2, S&K Link Layer email WWW phone...! SMTP HTTP RTP...! TCP UDP!! IP!! ethernet PPP! CSMA async sonet...! copper

More information

Chapter 6 Medium Access Control Protocols and Local Area Networks

Chapter 6 Medium Access Control Protocols and Local Area Networks Chapter 6 Medium Access Control Protocols and Local Area Networks Part I: Medium Access Control Part II: Local Area Networks CSE 3213, Winter 2010 Instructor: Foroohar Foroozan Chapter Overview Broadcast

More information

Introduction to LAN Protocols

Introduction to LAN Protocols CHAPTER 2 Introduction to LAN Protocols This chapter introduces the various media-access methods, transmission methods, topologies, and devices used in a local area network (LAN). Topics addressed focus

More information

Outline: Connecting Many Computers

Outline: Connecting Many Computers Outline: Connecting Many Computers Last lecture: sending data between two computers This lecture: link-level network protocols (from last lecture) sending data among many computers 1 Review: A simple point-to-point

More information

Chapter 5 Link Layer. Computer Networking: A Top Down Approach. 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012

Chapter 5 Link Layer. Computer Networking: A Top Down Approach. 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 Chapter 5 Link Layer A note on the use of these ppt slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you see the animations; and can

More information

Chapter 5 Link Layer and LANs

Chapter 5 Link Layer and LANs Chapter 5 Link Layer and LANs A note on the use of these ppt slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you can add, modify, and

More information

Principles behind data link layer services

Principles behind data link layer services Data link layer Goals: Principles behind data link layer services Error detection, correction Sharing a broadcast channel: Multiple access Link layer addressing Reliable data transfer, flow control: Done!

More information

transferring datagram from one node data-link layer has responsibility of to adjacent node over a link 5-1 TDTS06 Computer networks

transferring datagram from one node data-link layer has responsibility of to adjacent node over a link 5-1 TDTS06 Computer networks TDTS06 Computer networks Lecture 7: The link layer I Link Layer: Introduction Some terminology: hosts and routers are nodes communication channels that connect adjacent nodes along communication path are

More information

Underlying Technologies -Continued-

Underlying Technologies -Continued- S465 omputer Networks Spring 2004 hapter 3 (Part B) Underlying Technologies -ontinued- Dr. J. Harrison These slides were produced from material by Behrouz Forouzan for the text TP/IP Protocol Suite (2

More information

Adaptors Communicating. Link Layer: Introduction. Parity Checking. Error Detection. Multiple Access Links and Protocols

Adaptors Communicating. Link Layer: Introduction. Parity Checking. Error Detection. Multiple Access Links and Protocols Link Layer: Introduction daptors ommunicating hosts and routers are nodes links connect nodes wired links wireless links layer-2 packet is a frame, encapsulates datagram datagram controller sending host

More information

Packet multiple access and the Aloha protocol

Packet multiple access and the Aloha protocol Packet multiple access and the Aloha protocol Massachusetts Institute of Technology Department of Aeronautics and Astronautics Slide 1 Packet Multiple Access PMA SHARED UPLINK TERMINAL TERMINAL APPL TRANS

More information

Chapter 4 Network Layer

Chapter 4 Network Layer Chapter 4 Network Layer Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 Slides adopted from original ones provided by the textbook authors. Network

More information

Integrating Information Systems: Technology, Strategy, and Organizational Factors

Integrating Information Systems: Technology, Strategy, and Organizational Factors MASSACHUSETTS INSTITUTE OF TECHNOLOGY SLOAN SCHOOL OF MANAGEMENT 15.565 Integrating Information Systems: Technology, Strategy, and Organizational Factors 15.578 Global Information Systems: Communications

More information

Data Link Layer: Collisions

Data Link Layer: Collisions Data Link Layer: Collisions 1 Multiple Access Data Link layer divided into two sublayers. The upper sublayer is responsible for datalink control, The lower sublayer is responsible for resolving access

More information

Chapter 11 in Stallings 10 th Edition

Chapter 11 in Stallings 10 th Edition Local Area Network Overview Chapter 11 in Stallings 10 th Edition CS420/520 Axel Krings Page 1 LAN Applications (1) Personal computer LANs Low cost Limited data rate Back end networks Interconnecting large

More information

Lecture 05 Chapter 16 High Speed LANs

Lecture 05 Chapter 16 High Speed LANs NET 456 High Speed Networks Lecture 05 Chapter 16 High Speed LANs Dr. Anis Koubaa Reformatted slides from textbook Data and Computer Communications, Ninth Edition by William Stallings, 1 (c) Pearson Education

More information

Data Link Protocols. TCP/IP Suite and OSI Reference Model. The TCP/IP protocol stack does not define the lower layers of a complete protocol stack

Data Link Protocols. TCP/IP Suite and OSI Reference Model. The TCP/IP protocol stack does not define the lower layers of a complete protocol stack Data Link Protocols TCP/IP Suite and OSI Reference Model The TCP/IP protocol stack does not define the lower layers of a complete protocol stack In this lecture, we will address how the TCP/IP protocol

More information

Multiple Access (1) Required reading: Garcia 6.1, 6.2.1, CSE 3213, Fall 2010 Instructor: N. Vlajic

Multiple Access (1) Required reading: Garcia 6.1, 6.2.1, CSE 3213, Fall 2010 Instructor: N. Vlajic 1 Multiple Access (1) Required reading: Garcia 6.1, 6.2.1, 6.2.2 CSE 3213, Fall 2010 Instructor: N. Vlajic Multiple Access Communications 2 Broadcast Networks aka multiple access networks multiple sending

More information

Chapter 5: The Data Link Layer

Chapter 5: The Data Link Layer Chapter 5: The Data Link Layer Our goals: principles behind data link layer services: error detection, correction sharing a broadcast channel: multiple access link layer addressing reliable data transfer,

More information

CSE 461 Multiple Access. David Wetherall

CSE 461 Multiple Access. David Wetherall CSE 461 Multiple Access David Wetherall djw@cs.washington.edu How to share a link Multiplexing = networking term for sharing a resource among multiple users (e.g., link, protocol instance) Topics: Multiplexing

More information

Contention Protocols and Networks

Contention Protocols and Networks 4/13/2005 314 Lecture Contention Protocols and Networks 1 Contention Protocols and Networks Contention Protocols CSMA/CD Network Topologies Ethernet 4/13/2005 314 Lecture Contention Protocols and Networks

More information

LANs do not normally operate in isolation. They are connected to one another or to the Internet. To connect LANs, connecting devices are needed.

LANs do not normally operate in isolation. They are connected to one another or to the Internet. To connect LANs, connecting devices are needed. LAN interconnecting devices INTRODUCTION LANs do not normally operate in isolation. They are connected to one another or to the Internet. To connect LANs, connecting devices are needed. Connecting devices

More information

Local Area Network(LAN)

Local Area Network(LAN) Local Area Network() Sarawuth Chaimool ศราว ธ ช ยม ล jaounarak@hotmail.com Wireless Communications Research Group (WCR) Department of Electrical Engineering King Mongkut s Institute of Technology North

More information

Data Link Layer, Part 3 Medium Access Control. Preface

Data Link Layer, Part 3 Medium Access Control. Preface Data Link Layer, Part 3 Medium Access Control These slides are created by Dr. Yih Huang of George Mason University. Students registered in Dr. Huang's courses at GMU can make a single machine-readable

More information

Computer Networks. Medium Access Sublayer (Part I)

Computer Networks. Medium Access Sublayer (Part I) Computer Networks Medium Access Sublayer (Part I) Topics Introduction Multiple Access Protocols Ethernet Wireless LAN Protocols Bridges Misc (brief) High-Speed LANs Satellite Networks Introduction Remember,

More information

Multiple Access Communications. EEE 538, WEEK 11 Dr. Nail Akar Bilkent University Electrical and Electronics Engineering Department

Multiple Access Communications. EEE 538, WEEK 11 Dr. Nail Akar Bilkent University Electrical and Electronics Engineering Department Multiple Access Communications EEE 538, WEEK 11 Dr. Nail Akar Bilkent University Electrical and Electronics Engineering Department 1 Multiple Access Satellite systems, radio networks (WLAN), ethernet segment

More information

Hubs, Bridges, and Switches (oh my) Hubs

Hubs, Bridges, and Switches (oh my) Hubs Hubs, Bridges, and Switches (oh my) Used for extending LANs in terms of geographical coverage, number of nodes, administration capabilities, etc. Differ in regards to: collision domain isolation layer

More information

Multiple Access Protocols

Multiple Access Protocols Multiple Access Protocols Computer Networks Lecture 2 http://goo.gl/pze5o8 Multiple Access to a Shared Channel The medium (or its sub-channel) may be shared by multiple stations (dynamic allocation) just

More information

CSCI-1680 Link Layer Wrap-Up Rodrigo Fonseca

CSCI-1680 Link Layer Wrap-Up Rodrigo Fonseca CSCI-1680 Link Layer Wrap-Up Rodrigo Fonseca Based partly on lecture notes by David Mazières, Phil Levis, John Jannotti Administrivia Homework I out later today, due next Thursday Today: Link Layer (cont.)

More information

Switching and Forwarding Reading: Chapter 3 1/30/14 1

Switching and Forwarding Reading: Chapter 3 1/30/14 1 Switching and Forwarding Reading: Chapter 3 1/30/14 1 Switching and Forwarding Next Problem: Enable communication between hosts that are not directly connected Fundamental Problem of the Internet or any

More information

CCNA Exploration1 Chapter 7: OSI Data Link Layer

CCNA Exploration1 Chapter 7: OSI Data Link Layer CCNA Exploration1 Chapter 7: OSI Data Link Layer LOCAL CISCO ACADEMY ELSYS TU INSTRUCTOR: STELA STEFANOVA 1 Explain the role of Data Link layer protocols in data transmission; Objectives Describe how the

More information

Data Link Layer -2- Network Access

Data Link Layer -2- Network Access EITF25 Internet: Technology and Applications Data Link Layer -2- Network Access 2013, Lecture 03 Kaan Bür, Stefan Höst Previously on EITF25 Logical Link Control Sublayer Flow control Send data Wait for

More information

CS 716: Introduction to communication networks. - 9 th class; 19 th Aug Instructor: Sridhar Iyer IIT Bombay

CS 716: Introduction to communication networks. - 9 th class; 19 th Aug Instructor: Sridhar Iyer IIT Bombay CS 716: Introduction to communication networks - 9 th class; 19 th Aug 2011 Instructor: Sridhar Iyer IIT Bombay Contention-based MAC: ALOHA Users transmit whenever they have data to send Collisions occur,

More information

Switched Ethernet Virtual LANs

Switched Ethernet Virtual LANs Switched Ethernet Virtual LANs Computer Networks Lecture 4 http://goo.gl/pze5o8 Switched Ethernet 2 LAN Switches Behave as bridges (operates in the logical tree topology) Switching is implemented by hardware

More information

Lecture 6 Datalink Framing, Switching. From Signals to Packets

Lecture 6 Datalink Framing, Switching. From Signals to Packets Lecture 6 Datalink Framing, Switching David Andersen Department of Computer Science Carnegie Mellon University 15-441 Networking, Spring 2005 http://www.cs.cmu.edu/~srini/15-441/s05/ 1 From Signals to

More information

A closer look at network structure:

A closer look at network structure: T1: Introduction 1.1 What is computer network? Examples of computer network The Internet Network structure: edge and core 1.2 Why computer networks 1.3 The way networks work 1.4 Performance metrics: Delay,

More information

Computer Networks. Wenzhong Li. Nanjing University

Computer Networks. Wenzhong Li. Nanjing University Computer Networks Wenzhong Li Nanjing University 1 Chapter 2. Direct Link Networks Link Service and Framing Error Detection and Reliable Transmission HDLC, PPP, and SONET Token Ring Ethernet Bridges and

More information

Media Access Control. Networked Systems (H) Lecture 5

Media Access Control. Networked Systems (H) Lecture 5 Media Access Control Networked Systems (H) Lecture 5 Lecture Outline Controlling access to the channel Link contention Media access control protocols Contention-based protocols CSMA/CD Token ring Slotted

More information

Internetwork Basic. Possible causes of LAN traffic congestion are

Internetwork Basic. Possible causes of LAN traffic congestion are Internetworking 1 C H A P T E R 2 Internetworking Basics Internetworking Model The OSI Reference Model Ethernet Networking Wireless Networking Data Encapsulation Topic 3 1 Internetwork Basic 4 Possible

More information

A LAN is a high-speed data network that covers a relatively small geographic area. It typically connects workstations, personal computers, printers,

A LAN is a high-speed data network that covers a relatively small geographic area. It typically connects workstations, personal computers, printers, CBCN4103 A LAN is a high-speed data network that covers a relatively small geographic area. It typically connects workstations, personal computers, printers, servers, and other devices. LANs offer computer

More information

Chapter 6 The Data Link layer

Chapter 6 The Data Link layer Chapter 6 The Data Link layer 6.1 introduction, services 6.2 error detection, correction 6.3 multiple access protocols 6.4 LANs addressing, ARP Ethernet layer-2 switches VLANS 6.5 link virtualization:

More information

Multiple Access Links and Protocols

Multiple Access Links and Protocols Multiple Access Links and Protocols Two types of links : point-to-point PPP for dial-up access point-to-point link between Ethernet switch and host broadcast (shared wire or medium) old-fashioned Ethernet

More information

Chapter 4. The Medium Access Control Sublayer

Chapter 4. The Medium Access Control Sublayer Chapter 4 The Medium Access Control Sublayer The Channel Allocation Problem Static Channel Allocation in LANs and MANs Dynamic Channel Allocation in LANs and MANs Dynamic Channel Allocation in LANs and

More information

COMP/ELEC 429/556 Introduction to Computer Networks

COMP/ELEC 429/556 Introduction to Computer Networks COMP/ELEC 429/556 Introduction to Computer Networks Broadcast network access control Some slides used with permissions from Edward W. Knightly, T. S. Eugene Ng, Ion Stoica, Hui Zhang T. S. Eugene Ng eugeneng

More information

Physical and Link Layers. CS144 Review Session 6 November 6 th, 2008 Roger Liao Based on slides by Ben Nham

Physical and Link Layers. CS144 Review Session 6 November 6 th, 2008 Roger Liao Based on slides by Ben Nham Physical and Link Layers CS144 Review Session 6 November 6 th, 2008 Roger Liao Based on slides by Ben Nham Outline Physical layer Encoding of signals Chips vs. bits Link layer Communication through shared

More information

ECEN 5032 Data Networks Medium Access Control Sublayer

ECEN 5032 Data Networks Medium Access Control Sublayer ECEN 5032 Data Networks Medium Access Control Sublayer Peter Mathys mathys@colorado.edu University of Colorado, Boulder c 1996 2005, P. Mathys p.1/35 Overview (Sub)networks can be divided into two categories:

More information

We are going to see a basic definition of the devices you can find in a corporate wired network, so you can understand basic IT engineering jargon.

We are going to see a basic definition of the devices you can find in a corporate wired network, so you can understand basic IT engineering jargon. Computer network devices, also known as communication devices, are the backbone of a data communication network. In this category we can find routers, switches, hubs, LAN cards, gateways, modems, hardware

More information

Operating Systems. 16. Networking. Paul Krzyzanowski. Rutgers University. Spring /6/ Paul Krzyzanowski

Operating Systems. 16. Networking. Paul Krzyzanowski. Rutgers University. Spring /6/ Paul Krzyzanowski Operating Systems 16. Networking Paul Krzyzanowski Rutgers University Spring 2015 1 Local Area Network (LAN) LAN = communications network Small area (building, set of buildings) Same, sometimes shared,

More information

UNIT-II OVERVIEW OF PHYSICAL LAYER SWITCHING & MULTIPLEXING

UNIT-II OVERVIEW OF PHYSICAL LAYER SWITCHING & MULTIPLEXING 1 UNIT-II OVERVIEW OF PHYSICAL LAYER SWITCHING & MULTIPLEXING Syllabus: Physical layer and overview of PL Switching: Multiplexing: frequency division multiplexing, wave length division multiplexing, synchronous

More information

Announcements. TAs office hours: Mohamed Grissa: Mohamed Alkalbani:

Announcements. TAs office hours: Mohamed Grissa: Mohamed Alkalbani: Announcements TAs office hours: Mohamed Grissa: grissam@oregonstate.edu Tuesday: 4-5 Friday: 11-12 Mohamed Alkalbani: alkalbmo@oregonstate.edu Wednesday: 11-12 Thursday: 11-12 Lecture slides: Will be posted

More information

Media Access Control (MAC) Sub-layer and Ethernet

Media Access Control (MAC) Sub-layer and Ethernet Media Access Control (MAC) Sub-layer and Ethernet Dr. Sanjay P. Ahuja, Ph.D. Fidelity National Financial Distinguished Professor of CIS School of Computing, UNF MAC Sub-layer The MAC sub-layer is a sub-layer

More information

Mobile Wireless Networking Medium Access Control

Mobile Wireless Networking Medium Access Control Mobile Wireless Networking The University of Kansas EECS 882 Medium Access Control James P.G. Sterbenz Department of Electrical Engineering & Computer Science Information Technology & Telecommunications

More information

The Medium Access Sublayer

The Medium Access Sublayer The Medium Access Sublayer shivkuma@ecse.rpi.edu http://www.ecse.rpi.edu/homepages/shivkuma 1-1 Based in part upon the slides of Prof. Raj Jain (OSU), K. Vastola (RPI) Overview Multiple Access: Aloha,

More information

Jaringan Komputer. Broadcast Network. Outline. MAC (Medium Access Control) Channel Allocation Problem. Dynamic Channel Allocation

Jaringan Komputer. Broadcast Network. Outline. MAC (Medium Access Control) Channel Allocation Problem. Dynamic Channel Allocation Broadcast Network Jaringan Komputer Medium Access Control Sublayer 2 network categories: point-to-point connections broadcast channels Key issue in broadcast network: how to determine who gets to use the

More information

Ethernet. Introduction. CSE 3213 Fall 2011

Ethernet. Introduction. CSE 3213 Fall 2011 Ethernet CSE 3213 Fall 2011 19 October 2011 1 Introduction Rapid changes in technology designs Broader use of LANs New schemes for high-speed LANs High-speed LAN technologies: Fast and gigabit Ethernet

More information

Lecture 4b. Local Area Networks and Bridges

Lecture 4b. Local Area Networks and Bridges Lecture 4b Local Area Networks and Bridges Ethernet Invented by Boggs and Metcalf in the 1970 s at Xerox Local area networks were needed to connect computers, share files, etc. Thick or Thin Ethernet Cable

More information

LANs Local Area Networks LANs provide an efficient network solution : To support a large number of stations Over moderately high speed

LANs Local Area Networks LANs provide an efficient network solution : To support a large number of stations Over moderately high speed Local Area Networks LANs provide an efficient network solution : To support a large number of stations Over moderately high speed With relatively small bit errors Multiaccess Protocols Communication among

More information

Chapter 4: The Medium Access Layer

Chapter 4: The Medium Access Layer Chapter 4: The Medium Access Layer Computer Networks Maccabe Computer Science Department The University of New Mexico September 2002 Medium Access Layer Point-to-point versus broadcast networks Broadcast

More information

Chapter 8 LAN Topologies

Chapter 8 LAN Topologies Chapter 8 LAN Topologies Point-to-Point Networks In a Point-to-Point network, each wire connects exactly two computers Point To Point Link Machine A Machine B Figure 1: Each line connects two machines

More information

Chapter 6 The Data Link layer

Chapter 6 The Data Link layer Chapter 6 The Data Link layer 6.1 introduction, services 6.2 error detection, correction 63 6.3 multiple lil access protocols 64LAN 6.4 LANs addressing, ARP Ethernet layer-2 switches VLANS 6.5 link virtualization:

More information

CHAPTER -1. Introduction to Computer Networks

CHAPTER -1. Introduction to Computer Networks CHAPTER -1 Introduction to Computer Networks PRELIMINARY DEFINITIONS computer network :: [Tanenbaum] a collection of autonomous computers interconnected by a single technology. communications network ::a

More information

Chapter 6 Medium Access Control Protocols and Local Area Networks

Chapter 6 Medium Access Control Protocols and Local Area Networks Chapter 6 Medium Access Control Protocols and Local Area Networks Part I: Medium Access Control Part II: Local Area Networks Chapter Overview Broadcast Networks All information sent to all users No routing

More information

Computer Communication Networks Lecture No. 1

Computer Communication Networks Lecture No. 1 Computer Communication Networks Lecture No. 1 Reference books used in lectures 1- Computer Networks, Tanenbaum 2- Communication networks, Sharam Hekmat 3- Computer Networks, a system approach, L. Peterson

More information

end systems, access networks, links circuit switching, packet switching, network structure

end systems, access networks, links circuit switching, packet switching, network structure Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge end systems, access networks, links 1.3 Network core circuit switching, packet switching, network structure 1.4 Delay, loss and throughput

More information

CS 43: Computer Networks Switches and LANs. Kevin Webb Swarthmore College December 5, 2017

CS 43: Computer Networks Switches and LANs. Kevin Webb Swarthmore College December 5, 2017 CS 43: Computer Networks Switches and LANs Kevin Webb Swarthmore College December 5, 2017 Ethernet Metcalfe s Ethernet sketch Dominant wired LAN technology: cheap $20 for NIC first widely used LAN technology

More information

Router Router Microprocessor controlled traffic direction home router DSL modem Computer Enterprise routers Core routers

Router Router Microprocessor controlled traffic direction home router DSL modem Computer Enterprise routers Core routers Router Router is a Microprocessor controlled device that forwards data packets across the computer network. It is used to connect two or more data lines from different net works. The function of the router

More information

2. LAN Topologies Gilbert Ndjatou Page 1

2. LAN Topologies Gilbert Ndjatou Page 1 2. LAN Topologies Two basic categories of network topologies exist, physical topologies and logical topologies. The physical topology of a network is the cabling layout used to link devices. This refers

More information

Lecture 6 - Link layer. Lecture 5 Review. Link Layer. Introduction, Services. Notes. Notes. Notes. Notes. Networks and Security. Jacob Aae Mikkelsen

Lecture 6 - Link layer. Lecture 5 Review. Link Layer. Introduction, Services. Notes. Notes. Notes. Notes. Networks and Security. Jacob Aae Mikkelsen Lecture 6 - Link layer Networks and Security Jacob Aae Mikkelsen IMADA October 21, 2013 October 21, 2013 1 / 91 Lecture 5 Review Explain in short the following abbreviations, and the concept behind it.

More information

Networks 15.2 Multiplexing Technologies Access Networks 15.5 Common Peripheral Interfaces

Networks 15.2 Multiplexing Technologies Access Networks 15.5 Common Peripheral Interfaces Chapter 15 Computer and Multimedia Networks 15.11 Basics of Computer and Multimedia Networks 15.2 Multiplexing Technologies 15.3 LAN and WAN 15.4 Access Networks 15.5 Common Peripheral Interfaces 15.6

More information

Growth. Individual departments in a university buy LANs for their own machines and eventually want to interconnect with other campus LANs.

Growth. Individual departments in a university buy LANs for their own machines and eventually want to interconnect with other campus LANs. Internetworking Multiple networks are a fact of life: Growth. Individual departments in a university buy LANs for their own machines and eventually want to interconnect with other campus LANs. Fault isolation,

More information

Distributed Queue Dual Bus

Distributed Queue Dual Bus Distributed Queue Dual Bus IEEE 802.3 to 802.5 protocols are only suited for small LANs. They cannot be used for very large but non-wide area networks. IEEE 802.6 DQDB is designed for MANs It can cover

More information

Bridging and Switching Basics

Bridging and Switching Basics CHAPTER 4 Bridging and Switching Basics This chapter introduces the technologies employed in devices loosely referred to as bridges and switches. Topics summarized here include general link-layer device

More information

Chapter 6 Wireless and Mobile Networks

Chapter 6 Wireless and Mobile Networks Chapter 6 Wireless and Mobile Networks Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2004. 6: Wireless and Mobile Networks 6

More information

Announcements: ECE/CS 372 introduction to computer networks. Assignment 4 due now. Chapter 7

Announcements: ECE/CS 372 introduction to computer networks. Assignment 4 due now. Chapter 7 ECE/CS 372 introduction to computer networks Announcements: Assignment 4 due now Chapter 7 Acknowledgement: slides drawn heavily from Kurose & Ross and Prof. Bechir Hamdaoui Chapter 7, slide 1 Wireless

More information

Layer 2 functionality bridging and switching

Layer 2 functionality bridging and switching Layer 2 functionality bridging and switching BSAD 141 Dave Novak Sources: Network+ Guide to Networks, Dean 2013 Overview Layer 2 functionality Error detection Bridges Broadcast and collision domains How

More information

Internet Architecture and Protocol

Internet Architecture and Protocol Internet Architecture and Protocol Set# 03 Local Area Networks Delivered By: Engr Tahir Niazi Layer Reference to Protocol Application Presentation Session Application FTP, Telnet, SMTP, HTTP, SNMP.. Transport

More information

CDMA-Based MAC Protocol for Wireless Ad Hoc Networks

CDMA-Based MAC Protocol for Wireless Ad Hoc Networks CDMA-Based MAC Protocol for Wireless Ad Hoc Networks Alaa Muqattash and Marwan Krunz Presented by: Habibullah Pagarkar for 600.647-Advanced Topics in Wireless Networks. JHU. Spring 04 Today s Presentation

More information

Chapter 2. Switch Concepts and Configuration. Part I

Chapter 2. Switch Concepts and Configuration. Part I Chapter 2 Switch Concepts and Configuration Part I CCNA3-1 Chapter 2-1 Note for Instructors These presentations are the result of a collaboration among the instructors at St. Clair College in Windsor,

More information

Internetworking Concepts Overview. 2000, Cisco Systems, Inc. 2-1

Internetworking Concepts Overview. 2000, Cisco Systems, Inc. 2-1 Internetworking Concepts Overview 2000, Cisco Systems, Inc. 2-1 2000, Cisco Systems, Inc. www.cisco.com ICND v1.0a 2-2 Objectives On completion of this chapter, you will be able to perform the following

More information

Medium Access Control Sublayer

Medium Access Control Sublayer Wireless (WLAN) Medium Access Control Sublayer Mahalingam Mississippi State University, MS October 20, 2014 Outline Medium Access Protocols Wireless (WLAN) 1 Medium Access Protocols ALOHA Slotted ALOHA

More information

Network Connectivity and Mobility

Network Connectivity and Mobility Network Connectivity and Mobility BSAD 141 Dave Novak Topics Covered Lecture is structured based on the five elements of creating a connected world from the text book (with additional content) 1. Network

More information

Chapter 6 Medium Access Control Protocols and Local Area Networks. Part I: Medium Access Control Part II: Local Area Networks

Chapter 6 Medium Access Control Protocols and Local Area Networks. Part I: Medium Access Control Part II: Local Area Networks Chapter 6 Medium Access Control Protocols and Local Area Networks Part I: Medium Access Control Part II: Local Area Networks Chapter Overview Broadcast Networks All information sent to all users No routing

More information

CS 428/528 Computer Networks Lecture 01. Yan Wang

CS 428/528 Computer Networks Lecture 01. Yan Wang 1 CS 428/528 Computer Lecture 01 Yan Wang 2 Motivation: Why bother? Explosive growth of networks 1989, 100,000 hosts on the Internet Distributed Applications and Systems E-mail, WWW, multimedia, distributed

More information

Data Link Protocols. TCP/IP Suite and OSI Reference Model

Data Link Protocols. TCP/IP Suite and OSI Reference Model Data Link Protocols Relates to Lab. This module covers data link layer issues, such as local area networks (LANs) and point-to-point links, Ethernet, and the Point-to-Point Protocol (PPP). 1 TCP/IP Suite

More information

Network Media and Layer 1 Functionality

Network Media and Layer 1 Functionality Network Media and Layer 1 Functionality BSAD 146 Dave Novak Dean, Chapter 3, pp 93-124 Objectives Introduction to transmission media Basic cabling Coaxial Twisted pair Optical fiber Basic wireless (NIC)

More information

Internet Structure. network edge:

Internet Structure. network edge: Midterm Review Internet Structure network edge: Hosts: clients and servers Server often in data centers access networks, physical media:wired, wireless communication links network core: interconnected

More information

Announcements: ECE/CS 372 introduction to computer networks. Assign 4 is due this Thursday Lab 4 is due next Tuesday Assignment 5 posted soon

Announcements: ECE/CS 372 introduction to computer networks. Assign 4 is due this Thursday Lab 4 is due next Tuesday Assignment 5 posted soon ECE/CS 372 introduction to computer networks Lecture 14 Announcements: Assign 4 is due this Thursday Lab 4 is due next Tuesday Assignment 5 posted soon Credit for lecture slides to Professor Bechir Hamdaoui

More information

Ethernet. Typical Setup. Names. Operations. Operations Switch: No Collisions EECS 122. Hub: Single Collision Domain

Ethernet. Typical Setup. Names. Operations. Operations Switch: No Collisions EECS 122. Hub: Single Collision Domain Overview Physical Layer MAC Bridged VLAN Link Aggregation XON/XOFF 802.11 Summary Overview Typical Setup Names Operations Perspective TOC TOC Overview Typical Setup Names Structure [rate][modulation][media

More information