1999, Scott F. Midkiff

Size: px
Start display at page:

Download "1999, Scott F. Midkiff"

Transcription

1 Lecture Topics Direct Link Networks: Multiaccess Protocols (.7) Multiaccess control IEEE 80.5 Token Ring and FDDI CS/ECpE 556: Computer Networks Originally by Scott F. Midkiff (ECpE) Modified by Marc Abrams (CS) Virginia Tech courses.cs.vt.edu/~cs556 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - Multiaccess Communication () Previous discussion considered point-to-point links Received signal is transmitted signal (plus noise) Many networks are such that received signal at one node depends on transmitted signal at two or more other nodes Satellite systems Radio networks Multi-tap bus systems Multiaccess Communication () Multiaccess media are communication media where received signal is sum of attenuated transmitted signals plus effects of delay, distortion, and noise Examples: Multitap bus (Ethernet) Radio (wireless) network ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - Medium Access Control -- MAC () With multiaccess media, protocol is needed to coordinate sharing of media Medium access control (MAC) protocol performs this function MAC is sublayer between data link control (DLC) layer and physical layer (usually grouped with DLC) Medium Access Control -- MAC () LLC provides link to adjacent node MAC coordinates access to shared media Physical provides hardware interface Data Link LLC MAC physical ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 5 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols , Scott F. Midkiff

2 Medium Access Control -- MAC () Separation of layer functions in multiaccess networks is not as well-defined as in networks with point-to-point links Feedback about errors is part of ARQ strategy of DLC, but may depend on how media is shared Flow and congestion control needed to provide fair, efficient access to shared media Broadcast nature of shared media implements some routing functions Token Ring Networks Token ring networks are common form of LAN & MAN IEEE 80.5 (Token Ring): Mbps or 6 Mbps Fiber Distributed Data Interface (FDDI): 00 Mbps ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 7 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 8 Nodes Arranged in Ring Topology Nodes Arranged in Ring Topology 7 8 Node receives bit stream from last node relays bit stream to next node Node can repeat or replace each bit interface logic Point-to-point links between stations At least bit delay at each node: Propagation Processing Regeneration & transmission ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 9 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 0 Token () To transmit its own data, node must discard input & output its data interface logic But we can't discard data until it has reached its destination Token is used to coordinate use of ring Ring is shared medium, so network is multiaccess system Token () Conceptually, token is passed from node to node Only send your data when you've got token Pass token when data reaches destination or you've got no data to send So what is a token anyway? Special pattern -- distinguished from data Similar to framing flags ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 999, Scott F. Midkiff

3 Token () Token can be in states Free token (or idle token): ring available Discard bits following free token Busy token: ring in use Follow busy token with data Token indicates upcoming data (if busy), as well as permission to transmit (if free) Basic Token Ring Operation () When node with data to transmit receives free token, it marks token as busy and appends its own data Subsequent nodes forward data since token is marked busy Destination node both forwards and stores data Destination node may mark data as received, but token is still busy Data returns to originating node where it is discarded ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - Basic Token Ring Operation () Ring Example () After node finishes transmission, it marks token as free forwards token next node follows token with idle fill (until it sees busy or idle token again) data busy Node receives free token Node transmits busy token followed by data for node ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 5 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 6 Ring Example () Ring Example () idle free token Busy token followed by data continues around ring, node stores data Busy token completes round trip and is stripped at node Node strips old data from ring and transmits new data until finished When finished, node puts free token on ring, followed by idle fill ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 7 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols , Scott F. Midkiff

4 Ring Example () Ring Example (5) Node forwards free token (no data to send), node still storing data Node receives all of data from, forwards free token (no data to send) Node receives free token, transmits busy token followed by data Node forwards bits (busy token) after its last data bit arrives ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 9 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 0 Additional Details of Ring Operation Propagation delay around ring must be long enough to store complete token Otherwise first part of free token would be discarded to transmit last part Error detection Receiving node can check CRC and put an ACK or NAK in packet trailer on its way back to sender Sending node can also check CRC since it sees all transmitted data Numerous variations are possible in ring operation Token Holding Time How long can node hold free token? Option : Transmit only packet Lets token rotates at maximum rate Minimizes latency Option : Transmit all waiting packets Reduces token transmission overhead Maximizes throughput : Transmit waiting packets up to time limit Best of both worlds ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - Retransmission Schemes () options in handling retransmissions Selfless operation (FDDI): Give up token when done transmitting; if error detected, reacquire token & retransmit Selfish (IEEE 80.5): Hold token for round trip time, to be sure receiver got data correctly Pros/Cons Retransmission Schemes () Selfless (FDDI): Penalty: higher latency on error Selfish (80.5): Ring transmits idle fill until sender gets ack Penalty: lower throughput for low error rates Advantage: Lower latency for retransmissions ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 999, Scott F. Midkiff

5 Type of Token Failures () Lost token -- no node can transmit! Corrupted by noise (bit errors alter token code) Node holding token fails Token is permanently marked busy -- no node can transmit Idle token corrupted by noise (is marked busy) Multiple tokens created -- conflicts for access Non-token corrupted by noise to become token Node failure Ring protocol recognizes token failures & recovers (e.g. generating new token) ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 5 Fiber Distributed Data Interface -- FDDI 00 Mbps timed token ring network based on fiber optics Developed under auspices of ANSI committee XT9 formed in 98 Limited popularity Lack of high BW apps in 980's High cost of NIC's ($5000) and concentrators ($$) Was popular for backbones & switching fabric ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 6 FDDI Standard LLC Data Link Physical MAC PHY PMD SMT LLC Logical Link Control MAC Media Access Control PHY Physical PMD Physical Media Dependent SMT Station Management FDDI Versus Token Ring Token Ring: sender waits until all of transmitted data goes round ring before releasing token FDDI: sending node releases token after sending last bit of data Busy token not sent Data frame header recognized as busy token Improves FDDI s throughput FDDI supports low-priority (asynchronous) and high-priority (synchronous) packets Guarantees throughput and latency Suitable for digitized voice, real-time control, etc. ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 7 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 8 Capacity Allocation in FDDI () Capacity allocation for high-priority data is provided by timed token scheme Each node measures times between token arrivals Low-priority traffic can be sent only if intertoken time is sufficiently small High-priority traffic can be sent anytime token arrives Limited amount of high priority traffic can be sent for each token arrival (token holding time is limited) Guaranteed transmit time a i is allocated to node i ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 9 Capacity Allocation in FDDI () Target token rotation time (TTRT), t, is established when FDDI ring is initialized Used to determine when to send low-priority traffic It can be shown that: TTRT, t, is upper bound on time-average intertoken arrival time t is worst-case intertoken arrival time Transmission time for node i, a i, i = 0,,..., m- (m-node network), allocated such that α0 + α α m τ ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols , Scott F. Midkiff

6 Capacity Allocation in FDDI () To be more exact, other factors must be considered in setting TTRT, t Maximum propagation time around ring, T P,max Time to transmit maximum length frame (500 bytes), T F,max Token transmission time, T T So, allocations a i must be set such that m T + T + T + α τ P,max F,max T i Can group other factors into values i = 0 for a i Capacity Allocation in FDDI () Let t 0, t,..., t m-, be times at which token arrives at nodes 0,,..., m-, for some given cycle Assume that node k = (i mod m) receives token at time t i, i 0; node measures intertoken arrival time, t i - t i-m If t i - t i-m < t, node can send low-priority traffic for t - (t i - t i-m ) seconds and can send high-priority traffic for its allocated time of a k seconds ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - Capacity Allocation in FDDI (5) If t i - t i-m t, node cannot send low-priority traffic, but it can still send high-priority traffic for a k seconds Capacity Allocation Algorithm () All stations know same value for TTRT (t) and each has its own value a i Each node maintains two timers and counter Token rotation timer (TRT): Times intertoken arrival time (using LC) Token holding timer (THT): Times token holding time at node Late counter (LC): Counter for number of times that TRT expires ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - Capacity Allocation Algorithm () TRT is initialized to TTRT (t) and counts down, LC is 0 If token is received before TRT expires, TRT is reset to TTRT If TRT expires before token is received, LC is incremented to and TRT is reinitialized to TTRT If TRT expires second time, LC is incremented to and token is considered lost Capacity Allocation Algorithm () If token is received before TRT expires once (early token) THT is set to TRT (t - [t i - t i-m ]) TRT is reset to TTRT and started Station transmits high-priority frames until all are transmitted, but for at most a i seconds Station starts THT and transmits low-priority frames until done or THT expires ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 5 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols , Scott F. Midkiff

7 Capacity Allocation Algorithm () If TRT expires before token is received (late token) LC reset to 0, TRT resets ( rolls over ) Station can transmit high-priority frames for at most a i seconds (cannot transmit low-priority frames) Latency in FDDI For high-priority stream-type traffic, delay is bounded by t + T, where T is allocated traffic T m = i = 0 αi Delay is loosely bounded by t Short TTRT decreases delay, but at expense of efficiency (throughput) ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 7 ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols - 8 You should now be able to () Describe IEEE 80.5 LAN protocol Describe operation of Token Rings and FDDI Compare operation of FDDI to IEEE 80.5 Token Ring Analyze allocated capacity and latency in an FDDI network ECPE/CS 556 (//00) Direct Link Networks: Multiaccess Protocols , Scott F. Midkiff

Medium Access Control. IEEE , Token Rings. CSMA/CD in WLANs? Ethernet MAC Algorithm. MACA Solution for Hidden Terminal Problem

Medium Access Control. IEEE , Token Rings. CSMA/CD in WLANs? Ethernet MAC Algorithm. MACA Solution for Hidden Terminal Problem Medium Access Control IEEE 802.11, Token Rings Wireless channel is a shared medium Need access control mechanism to avoid interference Why not CSMA/CD? 9/15/06 CS/ECE 438 - UIUC, Fall 2006 1 9/15/06 CS/ECE

More information

IEEE , Token Rings. 10/11/06 CS/ECE UIUC, Fall

IEEE , Token Rings. 10/11/06 CS/ECE UIUC, Fall IEEE 802.11, Token Rings 10/11/06 CS/ECE 438 - UIUC, Fall 2006 1 Medium Access Control Wireless channel is a shared medium Need access control mechanism to avoid interference Why not CSMA/CD? 10/11/06

More information

FDDI by default supports Early Token Release. Below is the operation of FDDI ring.

FDDI by default supports Early Token Release. Below is the operation of FDDI ring. Lecture 9 Fault Tolerance FDDI is also built for fault tolerance. It is actually two networks, one going counter-clockwise and the other clockwise (as usually drawn). Normally only the primary links, i.e.

More information

ECE 333: Introduction to Communication Networks Fall Lecture 19: Medium Access Control VII

ECE 333: Introduction to Communication Networks Fall Lecture 19: Medium Access Control VII ECE : Introduction to Communication Networks Fall 2002 Lecture 9: Medium Access Control VII More on token ring networks LAN bridges and switches. More on token rings In the last lecture we began discussing

More information

Direct Link Networks: Building Blocks (2.1), Encoding (2.2), Framing (2.3)

Direct Link Networks: Building Blocks (2.1), Encoding (2.2), Framing (2.3) Direct Link Networks: Building Blocks (2.1), Encoding (2.2), Framing (2.3) ECPE/CS 5516: Computer Networks Originally by Scott F. Midkiff (ECpE) Modified by Marc Abrams (CS) Virginia Tech courses.cs.vt.edu/~cs5516

More information

Module 5. Broadcast Communication Networks. Version 2 CSE IIT, Kharagpur

Module 5. Broadcast Communication Networks. Version 2 CSE IIT, Kharagpur Module 5 Broadcast Communication Networks Lesson 5 High Speed LANs Token Ring Based Specific Instructional Objectives On completion, the student will be able to: Explain different categories of High Speed

More information

Goals. Fundamentals of Network Media. More topics. Topics. Multiple access communication. Multiple access solutions

Goals. Fundamentals of Network Media. More topics. Topics. Multiple access communication. Multiple access solutions Fundamentals of Network Media Local Area Networks Ursula Holmström Goals Learn the basic concepts related to LAN technologies, for example use of shared media medium access control topologies Know the

More information

ET4254 Communications and Networking 1

ET4254 Communications and Networking 1 Topic 10:- Local Area Network Overview Aims:- LAN topologies and media LAN protocol architecture bridges, hubs, layer 2 & 3 switches 1 LAN Applications (1) personal computer LANs low cost limited data

More information

FDDI. L26 - Fibre Distributed Data Interface (FDDI) L26 - Fibre Distributed Data Interface (FDDI) FDDI - Fiber Distributed Data Interface

FDDI. L26 - Fibre Distributed Data Interface (FDDI) L26 - Fibre Distributed Data Interface (FDDI) FDDI - Fiber Distributed Data Interface FDDI - Fiber Distributed Data Interface FDDI Fiber Distributed Data Interface Principles, Framing and Procedures set of standards defining a shared media 100 Mbps LAN (MAN) main topology: dual ring of

More information

TSIN01 Information Networks Lecture 3

TSIN01 Information Networks Lecture 3 TSIN01 Information Networks Lecture 3 Danyo Danev Division of Communication Systems Department of Electrical Engineering Linköping University, Sweden September 10 th, 2018 Danyo Danev TSIN01 Information

More information

Good day. In the last lecture, we talked about various multiple access schemes and one of this set of schemes is token bus DQD etc.

Good day. In the last lecture, we talked about various multiple access schemes and one of this set of schemes is token bus DQD etc. Computer Networks Prof. Sujoy Ghosh Department of Computer Science & Engineering Indian Institute of Technology, Kharagpur Lecture - 14 Token-Based MAC Good day. In the last lecture, we talked about various

More information

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

Local Area Networks (LANs) SMU CSE 5344 /

Local Area Networks (LANs) SMU CSE 5344 / Local Area Networks (LANs) SMU CSE 5344 / 7344 1 LAN/MAN Technology Factors Topology Transmission Medium Medium Access Control Techniques SMU CSE 5344 / 7344 2 Topologies Topology: the shape of a communication

More information

Data always flows in one direction around ring Like Ethernet, all nodes see all frames, and protocol is necessary to decide when to send

Data always flows in one direction around ring Like Ethernet, all nodes see all frames, and protocol is necessary to decide when to send Token Ring Developed by IBM, adopted by IEEE as 802.5 standard Token rings latter extended to FDDI (Fiber Distributed Data Interface) and 802.17 (Resilient Packet Ring) standards Nodes connected in a ring

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 Area Network. Review of Lecture 7. Review of Lecture 7. Review of Lecture 7. Review of Lecture 7. Review of Lecture 7.

Local Area Network. Review of Lecture 7. Review of Lecture 7. Review of Lecture 7. Review of Lecture 7. Review of Lecture 7. Review of Lecture 7 Local rea Network! Question - What are the station types supported by HDLC? Describe each. References: Chapters 15 and 16 Stallings Chapters 14 and 16 Forouzan Study Guide 8 Review

More information

CARRIER SENSE MULTIPLE ACCESS (CSMA):

CARRIER SENSE MULTIPLE ACCESS (CSMA): Lecture Handout Computer Networks Lecture No. 8 CARRIER SENSE MULTIPLE ACCESS (CSMA): There is no central control management when computers transmit on Ethernet. For this purpose the Ethernet employs CSMA

More information

Data Link Control Protocols

Data Link Control Protocols Protocols : Introduction to Data Communications Sirindhorn International Institute of Technology Thammasat University Prepared by Steven Gordon on 23 May 2012 Y12S1L07, Steve/Courses/2012/s1/its323/lectures/datalink.tex,

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

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

Chapter 15 Local Area Network Overview

Chapter 15 Local Area Network Overview Chapter 15 Local Area Network Overview LAN Topologies Bus and Tree Bus: stations attach through tap to bus full duplex allows transmission and reception transmission propagates throughout medium heard

More information

Data Link Technology. Suguru Yamaguchi Nara Institute of Science and Technology Department of Information Science

Data Link Technology. Suguru Yamaguchi Nara Institute of Science and Technology Department of Information Science Data Link Technology Suguru Yamaguchi Nara Institute of Science and Technology Department of Information Science Agenda Functions of the data link layer Technologies concept and design error control flow

More information

LAN. CS 4/55231 Internet Engineering. Kent State University Dept. of Computer Science

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

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

Local Area Networks transmission system private speedy and secure kilometres shared transmission medium hardware & software

Local Area Networks transmission system private speedy and secure kilometres shared transmission medium hardware & software Local Area What s a LAN? A transmission system, usually private owned, very speedy and secure, covering a geographical area in the range of kilometres, comprising a shared transmission medium and a set

More information

Link Layer and Ethernet

Link Layer and Ethernet Link Layer and Ethernet 14-740: Fundamentals of Computer Networks Bill Nace Material from Computer Networking: A Top Down Approach, 6 th edition. J.F. Kurose and K.W. Ross traceroute Data Link Layer Multiple

More information

Data Link Layer, Part 5. Medium Access Control

Data Link Layer, Part 5. Medium Access Control CS 455 Medium Access Control, Page 1 Data Link Layer, Part 5 Medium Access Control These slides are created by Dr. Yih Huang of George Mason University. Students registered in Dr. Huang s courses at GMU

More information

Direct Link Networks (II)

Direct Link Networks (II) Direct Link Networks (II) Computer Networking Lecture 03 HKU SPACE Community College January 30, 2012 HKU SPACE CC CN Lecture 03 1/25 Outline Reliable Link Service Stop-and-Wait Sliding Window Media Access

More information

CS 43: Computer Networks. 27: Media Access Contd. December 3, 2018

CS 43: Computer Networks. 27: Media Access Contd. December 3, 2018 CS 43: Computer Networks 27: Media Access Contd. December 3, 2018 Last Class The link layer provides lots of functionality: addressing, framing, media access, error checking could be used independently

More information

CS 455/555 Intro to Networks and Communications. Link Layer

CS 455/555 Intro to Networks and Communications. Link Layer CS 455/555 Intro to Networks and Communications Link Layer Dr. Michele Weigle Department of Computer Science Old Dominion University mweigle@cs.odu.edu http://www.cs.odu.edu/~mweigle/cs455-s13 1 Link Layer

More information

Computer Network Fundamentals Spring Week 3 MAC Layer Andreas Terzis

Computer Network Fundamentals Spring Week 3 MAC Layer Andreas Terzis Computer Network Fundamentals Spring 2008 Week 3 MAC Layer Andreas Terzis Outline MAC Protocols MAC Protocol Examples Channel Partitioning TDMA/FDMA Token Ring Random Access Protocols Aloha and Slotted

More information

Reminder: Datalink Functions Computer Networking. Datalink Architectures

Reminder: Datalink Functions Computer Networking. Datalink Architectures Reminder: Datalink Functions 15-441 15 441 15-641 Computer Networking Lecture 5 Media Access Control Peter Steenkiste Fall 2015 www.cs.cmu.edu/~prs/15-441-f15 Framing: encapsulating a network layer datagram

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

Direct Link Communication I: Basic Techniques. Data Transmission. ignore carrier frequency, coding etc.

Direct Link Communication I: Basic Techniques. Data Transmission. ignore carrier frequency, coding etc. Direct Link Communication I: Basic Techniques Link speed unit: bps abstraction Data Transmission ignore carrier frequency, coding etc. Point-to-point link: wired or wireless includes broadcast case Interested

More information

Link Layer and Ethernet

Link Layer and Ethernet Link Layer and Ethernet 14-740: Fundamentals of Computer Networks Bill Nace Material from Computer Networking: A Top Down Approach, 6 th edition. J.F. Kurose and K.W. Ross traceroute Data Link Layer Multiple

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

Lecture 9: Bridging. CSE 123: Computer Networks Alex C. Snoeren

Lecture 9: Bridging. CSE 123: Computer Networks Alex C. Snoeren Lecture 9: Bridging CSE 123: Computer Networks Alex C. Snoeren Lecture 9 Overview Finishing up media access Ethernet Contention-free methods (rings) Moving beyond one wire Link technologies have limits

More information

Direct Link Communication I: Basic Techniques. Data Transmission. ignore carrier frequency, coding etc.

Direct Link Communication I: Basic Techniques. Data Transmission. ignore carrier frequency, coding etc. Direct Link Communication I: Basic Techniques Link speed unit: bps abstraction Data Transmission ignore carrier frequency, coding etc. Point-to-point link: wired or wireless includes broadcast case Interested

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

Unit II. Part A (2 Marks)

Unit II. Part A (2 Marks) Unit II Part A (2 Marks) 1. Differentiate fast Ethernet and Gigabit Ethernet. Fast Ethernet increased speed from 10 to 100 megabits per second (Mbit/s). Gigabit Ethernet was the next iteration, increasing

More information

Lecture 26: Data Link Layer

Lecture 26: Data Link Layer Introduction We have seen in previous lectures that the physical layer is responsible for the transmission of row bits (Ones and Zeros) over the channel. It is responsible for issues related to the line

More information

SRI RAMAKRISHNA INSTITUTE OF TECHNOLOGY DEPARTMENT OF INFORMATION TECHNOLOGY COMPUTER NETWORKS UNIT - II DATA LINK LAYER

SRI RAMAKRISHNA INSTITUTE OF TECHNOLOGY DEPARTMENT OF INFORMATION TECHNOLOGY COMPUTER NETWORKS UNIT - II DATA LINK LAYER SRI RAMAKRISHNA INSTITUTE OF TECHNOLOGY DEPARTMENT OF INFORMATION TECHNOLOGY COMPUTER NETWORKS UNIT - II DATA LINK LAYER 1. What are the responsibilities of data link layer? Specific responsibilities of

More information

1. Data Link Layer Protocols

1. Data Link Layer Protocols 1. Data Link Layer Protocols Purpose of the Data Link Layer The Data Link Layer Purpose of the Data Link Layer Data Link Sublayers Network LLC Sublayer Data Link Physical MAC Sublayer 802.3 Ethernet 802.11

More information

Goal and Outline. Computer Networking. What Do We Need? Today s Story Lecture 3: Packet Switched Networks Peter Steenkiste

Goal and Outline. Computer Networking. What Do We Need? Today s Story Lecture 3: Packet Switched Networks Peter Steenkiste Goal and Outline 15-441 15-641 Computer Networking Lecture 3: Packet Switched Networks Peter Steenkiste Fall 2016 www.cs.cmu.edu/~prs/15 441 F16 Goal: gain a basic understanding of how you can build a

More information

Networking Link Layer

Networking Link Layer Networking Link Layer ECE 650 Systems Programming & Engineering Duke University, Spring 2018 (Link Layer Protocol material based on CS 356 slides) TCP/IP Model 2 Layer 1 & 2 Layer 1: Physical Layer Encoding

More information

Lecture 9: Bridging & Switching"

Lecture 9: Bridging & Switching Lecture 9: Bridging & Switching" CSE 123: Computer Networks Alex C. Snoeren HW 2 due Wednesday! Lecture 9 Overview" Finishing up media access Contention-free methods (rings) Moving beyond one wire Link

More information

SIMULATION OF PACKET DATA NETWORKS USING OPNET

SIMULATION OF PACKET DATA NETWORKS USING OPNET SIMULATION OF PACKET DATA NETWORKS USING OPNET Nazy Alborz, Maryam Keyvani, Milan Nikolic, and Ljiljana Trajkovic * School of Engineering Science Simon Fraser University Vancouver, British Columbia, Canada

More information

2.1 CHANNEL ALLOCATION 2.2 MULTIPLE ACCESS PROTOCOLS Collision Free Protocols 2.3 FDDI 2.4 DATA LINK LAYER DESIGN ISSUES 2.5 FRAMING & STUFFING

2.1 CHANNEL ALLOCATION 2.2 MULTIPLE ACCESS PROTOCOLS Collision Free Protocols 2.3 FDDI 2.4 DATA LINK LAYER DESIGN ISSUES 2.5 FRAMING & STUFFING UNIT-2 2.1 CHANNEL ALLOCATION 2.2 MULTIPLE ACCESS PROTOCOLS 2.2.1 Pure ALOHA 2.2.2 Slotted ALOHA 2.2.3 Carrier Sense Multiple Access 2.2.4 CSMA with Collision Detection 2.2.5 Collision Free Protocols 2.2.5.1

More information

Part 5: Link Layer Technologies. CSE 3461: Introduction to Computer Networking Reading: Chapter 5, Kurose and Ross

Part 5: Link Layer Technologies. CSE 3461: Introduction to Computer Networking Reading: Chapter 5, Kurose and Ross Part 5: Link Layer Technologies CSE 3461: Introduction to Computer Networking Reading: Chapter 5, Kurose and Ross 1 Outline PPP ATM X.25 Frame Relay 2 Point to Point Data Link Control One sender, one receiver,

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

Your favorite blog :www.vijay-jotani.weebly.com (popularly known as VIJAY JOTANI S BLOG..now in facebook.join ON FB VIJAY

Your favorite blog :www.vijay-jotani.weebly.com (popularly known as VIJAY JOTANI S BLOG..now in facebook.join ON FB VIJAY VISIT: Course Code : MCS-042 Course Title : Data Communication and Computer Network Assignment Number : MCA (4)/042/Assign/2014-15 Maximum Marks : 100 Weightage : 25% Last Dates for Submission : 15 th

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

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

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

CSE 461: Multiple Access Networks. This Lecture

CSE 461: Multiple Access Networks. This Lecture CSE 461: Multiple Access Networks This Lecture Key Focus: How do multiple parties share a wire? This is the Medium Access Control (MAC) portion of the Link Layer Randomized access protocols: 1. Aloha 2.

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

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 5.5: Ethernet Dr. Nghi Tran (ECE-University of Akron) ECE 4450:427/527 Computer Networks

More information

The Link Layer and LANs. Chapter 6: Link layer and LANs

The Link Layer and LANs. Chapter 6: Link layer and LANs The Link Layer and LANs EECS3214 2018-03-14 4-1 Chapter 6: Link layer and LANs our goals: understand principles behind link layer services: error detection, correction sharing a broadcast channel: multiple

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

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

Chapter 5 Link Layer and LANs

Chapter 5 Link Layer and LANs Chapter 5 Link Layer and LANs Computer Networking: A Top Down Approach 4 th edition. Jim Kurose, Keith Ross Addison-Wesley, July 2007. All material copyright 1996-2007 J.F Kurose and K.W. Ross, All Rights

More information

Computer Networks รศ.ดร.อน นต ผลเพ ม. Assoc. Prof. Anan Phonphoem, Ph.D. Kasetsart University, Bangkok, Thailand

Computer Networks รศ.ดร.อน นต ผลเพ ม. Assoc. Prof. Anan Phonphoem, Ph.D. Kasetsart University, Bangkok, Thailand Jan May 2018 Computer Networks รศ.ดร.อน นต ผลเพ ม Assoc. Prof. Anan Phonphoem, Ph.D. anan.p@ku.ac.th http://www.cpe.ku.ac.th/~anan Computer Engineering Department Kasetsart University, Bangkok, Thailand

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

Digital Communication Networks

Digital Communication Networks Digital Communication Networks MIT PROFESSIONAL INSTITUTE, 6.20s July 25-29, 2005 Professor Muriel Medard, MIT Professor, MIT Slide 1 Digital Communication Networks Introduction Slide 2 Course syllabus

More information

Computer Networks Medium Access Control. Mostafa Salehi Fall 2008

Computer Networks Medium Access Control. Mostafa Salehi Fall 2008 Computer Networks Medium Access Control Mostafa Salehi Fall 2008 2008 1 Outline Issues ALOHA Network Ethernet Token Ring Wireless 2 Main Issues Local Area Network (LAN) : Three or more machines are physically

More information

Data Networks. Lecture 1: Introduction. September 4, 2008

Data Networks. Lecture 1: Introduction. September 4, 2008 Data Networks Lecture 1: Introduction September 4, 2008 Slide 1 Learning Objectives Fundamental aspects of network Design and Analysis: Architecture: layering, topology design, switching mechanisms Protocols:

More information

CS 123: Lecture 12, LANs, and Ethernet. George Varghese. October 24, 2006

CS 123: Lecture 12, LANs, and Ethernet. George Varghese. October 24, 2006 CS 123: Lecture 12, LANs, and Ethernet George Varghese October 24, 2006 Selective Reject Modulus failure Example w = 2, Max = 3 0 0 1 3 0 A(1) A(2) 1 0 retransmit A(1) A(2) buffer Case 1 Case 2 reject

More information

Physical and Data Link layers

Physical and Data Link layers Physical and Data Link layers Youki Kadobayashi Graduate School of Science Nara Institute of Science and Technology Physical Layer All rights reserved. 2 Types of transmission medium! Cables Optical fiber

More information

Overview. Data Link Technology. Role of the data-link layer. Role of the data-link layer. Function of the physical layer

Overview. Data Link Technology. Role of the data-link layer. Role of the data-link layer. Function of the physical layer Overview Data Link Technology Functions of the data link layer Technologies concept and design error control flow control fundamental protocols Suguru Yamaguchi Nara Institute of Science and Technology

More information

1/29/2008. From Signals to Packets. Lecture 6 Datalink Framing, Switching. Datalink Functions. Datalink Lectures. Character and Bit Stuffing.

1/29/2008. From Signals to Packets. Lecture 6 Datalink Framing, Switching. Datalink Functions. Datalink Lectures. Character and Bit Stuffing. /9/008 From Signals to Packets Lecture Datalink Framing, Switching Peter Steenkiste Departments of Computer Science and Electrical and Computer Engineering Carnegie Mellon University Analog Signal Digital

More information

Token Ring and. Fiber Distributed Data Interface (FDDI) Networks: Token Ring and FDDI 1

Token Ring and. Fiber Distributed Data Interface (FDDI) Networks: Token Ring and FDDI 1 Token Ring and Fiber Distributed Data Interface (FDDI) Networks: Token Ring and FDDI 1 IEEE 802.5 Token Ring Proposed in 1969 and initially referred to as a Newhall ring. Token ring :: a number of stations

More information

COMPUTER NETWORKS MODEL QUESTION PAPER WITH SOLUTION. (c) Peer-to-peer processes are processes on two or more devices communicating at a

COMPUTER NETWORKS MODEL QUESTION PAPER WITH SOLUTION. (c) Peer-to-peer processes are processes on two or more devices communicating at a COMPUTER NETWORKS MODEL QUESTION PAPER WITH SOLUTION Q-1(a) In half-duplex transmission, only one entity can send at a time; in a full-duplex transmission, both entities can send at the same time. (b)

More information

M242 COMPUTER NETWORS AND SECURITY

M242 COMPUTER NETWORS AND SECURITY M242 COMPUTER NETWORS AND SECURITY 2.1. Network Models: UNIT - II OSI MODEL AND LAN PROTOCOLS 1. Explain Network model A network is a combination of hardware and software that sends data from one location

More information

CSE/EE 461 Section 2

CSE/EE 461 Section 2 CSE/EE 461 Section 2 Latency in a store-and-forward network 4ms, 10MB/s B How long does it take to send a 2kB packet from to B? 2ms, 10MB/s C 2ms, 10MB/s B What if it has to pass through a node C? Plan

More information

Lecture 11 Overview. Last Lecture. This Lecture. Next Lecture. Medium Access Control. Flow and error control Source: Sections , 23.

Lecture 11 Overview. Last Lecture. This Lecture. Next Lecture. Medium Access Control. Flow and error control Source: Sections , 23. Last Lecture Lecture 11 Overview Medium Access Control This Lecture Flow and error control Source: Sections 11.1-11.2, 23.2 Next Lecture Local Area Networks 1 Source: Sections 13 Data link layer Logical

More information

Lecture 6: Example LAN: Ethernet

Lecture 6: Example LAN: Ethernet Lecture 6: Example LAN: Ethernet Dr. Mohammed Hawa Electrical Engineering Department University of Jordan EE426: Communication Networks Network Types Local Area Networks (LANs):privately-owned networks

More information

DP83261 BMAC TM Device (FDDI Media Access Controller)

DP83261 BMAC TM Device (FDDI Media Access Controller) DP83261 BMAC TM Device (FDDI Media Access Controller) General Description The DP83261 BMAC device implements the Media Access Control (MAC) protocol for operation in an FDDI token ring The BMAC device

More information

16.682: Communication Systems Engineering. Lecture 17. ARQ Protocols

16.682: Communication Systems Engineering. Lecture 17. ARQ Protocols 16.682: Communication Systems Engineering Lecture 17 ARQ Protocols Eytan Modiano Automatic repeat request (ARQ) Break large files into packets FILE PKT H PKT H PKT H Check received packets for errors Use

More information

Link Layer and LANs 안상현서울시립대학교컴퓨터 통계학과.

Link Layer and LANs 안상현서울시립대학교컴퓨터 통계학과. Link Layer and LANs 안상현서울시립대학교컴퓨터 통계학과 ahn@venus.uos.ac.kr Data Link Layer Goals: understand principles behind data link layer services: error detection, correction sharing a broadcast channel: multiple

More information

The MAC Address Format

The MAC Address Format Directing data is what addressing is all about. At the Data Link layer, this is done by pointing PDUs to the destination MAC address for delivery of a frame within a LAN. The MAC address is the number

More information

IEEE standards for local area networks

IEEE standards for local area networks IEEE standards for local area networks Telecommunication Networks Group firstname.lastname@polito.it http://www.telematica.polito.it/ COMPUTER NETWORKS Standard for LANs 1 Copyright Quest opera è protetta

More information

UNIT II DATA LINK LAYER 10

UNIT II DATA LINK LAYER 10 UNIT II DATA LINK LAYER 10 Error detection and correction Parity LRC CRC Hamming code flow Control and Error control - stop and wait go back-n ARQ selective repeat ARQ- sliding window HDLC. - LAN - Ethernet

More information

Internetworking Part 1

Internetworking Part 1 CMPE 344 Computer Networks Spring 2012 Internetworking Part 1 Reading: Peterson and Davie, 3.1 22/03/2012 1 Not all networks are directly connected Limit to how many hosts can be attached Point-to-point:

More information

William Stallings Data and Computer Communications. Chapter 7 Data Link Control

William Stallings Data and Computer Communications. Chapter 7 Data Link Control William Stallings Data and Computer Communications Chapter 7 Data Link Control Flow Control Ensuring the sending entity does not overwhelm the receiving entity Preventing buffer overflow Transmission time

More information

Introduction to Networks and the Internet

Introduction to Networks and the Internet Introduction to Networks and the Internet HTML tutorial today. Announcements CMPE 80N Spring 2003 Week 5 1 2 MAC Protocols MAC Protocols Round-robin. Scheduled-access. Contention-based. Contention-based

More information

Links Reading: Chapter 2. Goals of Todayʼs Lecture. Message, Segment, Packet, and Frame

Links Reading: Chapter 2. Goals of Todayʼs Lecture. Message, Segment, Packet, and Frame Links Reading: Chapter 2 CS 375: Computer Networks Thomas Bressoud 1 Goals of Todayʼs Lecture Link-layer services Encoding, framing, and error detection Error correction and flow control Sharing a shared

More information

Introductory to Computer Networks Local Area Networks. Lecture 16 Fall Isfahan University of technology Dr.

Introductory to Computer Networks Local Area Networks. Lecture 16 Fall Isfahan University of technology Dr. Introductory to Computer Networks Local Area Networks Lecture 16 Fall 2010 Isfahan University of technology Dr. Faramarz Hendessi What is a LAN? Local area means: Private ownership freedom from regulatory

More information

LAN Overview (part 2) Interconnecting LANs - Hubs

LAN Overview (part 2) Interconnecting LANs - Hubs LAN Overview (part 2) CSE 3213 Fall 2011 1 November 2011 Interconnecting LANs - Hubs active central element of star layout each station connected to hub by two UTP lines hub acts as a repeater limited

More information

ECE4110 Internetwork Programming. Introduction and Overview

ECE4110 Internetwork Programming. Introduction and Overview ECE4110 Internetwork Programming Introduction and Overview 1 EXAMPLE GENERAL NETWORK ALGORITHM Listen to wire Are signals detected Detect a preamble Yes Read Destination Address No data carrying or noise?

More information

Links. CS125 - mylinks 1 1/22/14

Links. CS125 - mylinks 1 1/22/14 Links 1 Goals of Today s Lecture Link-layer services Encoding, framing, and error detection Error correction and flow control Sharing a shared media Channel partitioning Taking turns Random access Shared

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

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

Data Link Layer (cont.) ( h h h ) (Sicherungsschicht) HDLC - 1.

Data Link Layer (cont.) ( h h h ) (Sicherungsschicht) HDLC - 1. Data Link Layer (cont.) ( h h h ) (Sicherungsschicht) HDLC - 1 LOGICAL L LINK CONTROL MEDIUM ACCESS CONTROL PHYSICAL SIGNALING DATA LINK LAYER PHYSICAL LAYER ACCESS UNIT INTERFACE PHYSICAL MEDIA ATTACHMENT

More information

Multiple Access Channels

Multiple Access Channels Multiple Access Channels Some Queuing Theory MAC: Aloha, ethernet Exponential backoff & friends LANs: Local Area Networks Goal: extend benefits of simple connection as far as possible Means: Share medium

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 7. OSI Data Link Layer. CCNA1-1 Chapter 7

Chapter 7. OSI Data Link Layer. CCNA1-1 Chapter 7 Chapter 7 OSI Data Link Layer CCNA1-1 Chapter 7 Note for Instructors These presentations are the result of a collaboration among the instructors at St. Clair College in Windsor, Ontario. Thanks must go

More information

Chapter 7. OSI Data Link Layer

Chapter 7. OSI Data Link Layer Chapter 7 OSI Data Link Layer CCNA1-1 Chapter 7 Note for Instructors These presentations are the result of a collaboration among the instructors at St. Clair College in Windsor, Ontario. Thanks must go

More information

Department of Computer and IT Engineering University of Kurdistan. Data Communication Netwotks (Graduate level) Data Link Layer

Department of Computer and IT Engineering University of Kurdistan. Data Communication Netwotks (Graduate level) Data Link Layer Department of Computer and IT Engineering University of Kurdistan Data Communication Netwotks (Graduate level) Data Link Layer By: Dr. Alireza Abdollahpouri Data Link Layer 2 Data Link Layer Application

More information

Chapter 4: Network Access

Chapter 4: Network Access 4.0.1.1 Chapter 4: Network Access To support our communication, the OSI model divides the functions of a data network into layers. Each layer works with the layers above and below to transmit data. 4.0.1.2

More information

Data and Computer Communications

Data and Computer Communications Data and Computer Communications Chapter 16 High Speed LANs Eighth Edition by William Stallings Why High Speed LANs? speed and power of PCs has risen graphics-intensive applications and GUIs see LANs as

More information