# Data Link Layer(1) Principal service: Transferring data from the network layer of the source machine to the one of the destination machine

Save this PDF as:

Size: px
Start display at page:

Download "Data Link Layer(1) Principal service: Transferring data from the network layer of the source machine to the one of the destination machine"

## Transcription

1 Data Link Layer(1) Principal service: Transferring data from the network layer of the source machine to the one of the destination machine Virtual communication versus actual communication: Specific functions to carry out: determining how the bits of the physical layer are grouped into frames dealing with transmission errors providing flow control

2 Data Link Layer(2) Grouping into frames Methods for framing: character count character stuffing bit stuffing exploiting redundancy in the physical layer Example for character count:

3 Data Link Layer(3) Example for character stuffing: Example for bit stuffing:

4 Data Link Layer(4) Dealing with transmission errors Error Detecting Codes (EDC) and Error Correcting Codes (ECC) Definitions: Codeword:= source (original, payload) word + (redundant) check (control) bits m:= length of the source word (number of information bits) r:= number of check bits n:= m + r := length of the codeword ---> A binary code is a subset of R 2 n. Ist elements (words) also can be considered as code vectors. / Use of ECCs : Heavily disturbed transmission channels Data transmission via wireless transmitters (insbesondere bei militärischen Anwendungen) Secondary storage media, to correct reading errors without repeating the reading procedure Hamming distance: Let x and y be codewords in R 2 n. The function d(x,y):= x i +y i witht i= 1,...,n is called Hamming distance of x and y. The Hamming distance of the entire code (set of all correct codewords) is defined as the minimal Hamming distance between any 2 codewords of this code.

5 Data Link Layer(4a) Illustration of the principle of Error-Correcting Codes (ECC s) and Error-Detecting Codes (EDC s): 3-dimensional representation of codes:

6 Data Link Layer(5) Lower limits on the number of check bits needed to correct single errors depending on the word size: Each of the 2 m legal codewords has n illegal codewords at a distance 1 dedicated to it ---> (n+1) 2 m <= 2 n. Using n = m+ r ---> (m+ r +1) <= 2 r Some numbers for r depending on m:

7 Principal idea of the Hamming - Code: Data Link Layer(6) A B C

8 Data Link Layer(7) Example: parity bit 1 wrong (1,3,5,7,9,11,13,15,17,19,21 contain altogether 5 Ones) parity bit 2 correct (2,3,6,7,10,11,14,15,18,19, contain altogether 6 Ones) parity bit 4 wrong (4,5,6,7,12,13,14,15,20,21 contain altogether 5 Ones) parity bit 8 correct (8,9,10,11,12,13,14,15 contain altogether 2 Ones) parity bit 16 correct (16,17,18,19,20,21 contain altogether 4 Ones) ---> Bit No. 5 is wrong and has to be inverted!

9 Data Link Layer(8) Use of the Hamming - Code to correct burst errors: Parity code with odd and even parities:

10 Data Link Layer(10) Idea of the Polynomial or Cyclic Redundancy Code (CRC): Treat bit strings as representations of polynomials with coefficients of 0 and 1 only. Sender and receiver must agree upon a generator polynomial G(x) The sender computes the checksummed polynomial T(x) to be sent such that T(x) is divisible by G(x) The receiver divides the received T(x) by G(x). If there is a remainder ---> Error!!! Algorithm for computing the checksum: 1. Let r be the degree of G(x). Append r zero bits to the low-order end of the frame, so it now contains m+r bits and corresponds to the polynomial x r M(x). 2. Divide the bit string corresponding to G(x) into the bit string corresponding to x r M(x) using modulo 2 division. 3. Subtract the remainder (which is always r or fewer bits) from the bit string corresponding to x r M(x) using modulo 2 subtraction. The result is the checksummed frame to be transmitted. Call its polynomial T(x).

12 Data Link Layer(12) Three (generator) polynomials have become international standards: CRC-12 = x 12 +x 11 +x 3 +x 2 +x 1 +1 CRC-16 = x 16 +x 15 +x 2 +1 CRC-CCITT = x 16 +x 12 +x 5 +1 Properties of a 16-bit checksum (such as CRC-16 and CRC-CCITT): It catches all single and double errors all errors with an odd number of bits all burst errors of length 16 or less % of 17-bit error bursts % of 18-bit and longer bursts

13 Data Link Layer(13) Providing Flow Control A Simplex Stop-and-Wait Protocol Assumptions: No infinite amount of buffer space available on the receiver s side Communication channel is assumed to be error-free and data traffic is simplex Problem: How to prevent the sender from flooding the receiver with data faster than the latter is able to process Solution approach: Having the receiver provide feedback to the sender by acknowledging each frame sent ---> the sender must wait until an ack frame arrives before fetching the next frame from the network layer Remark: Data traffic is simplex, but frames do travel in both directions (bidirectional information transfer) ---> the physical communication channel must be duplex or at least half-duplex Piggybacking (if data traffic is duplex): Delaying outgoing acks so that they can be hooked on the next outgoing data frame (having a separate ack field in its header) Principal advantage over having separate ack frames: Better use of the available channel bandwidth

14 Data Link Layer(14) Sliding window protocols Assumptions: Data traffic is duplex Sender`s data frame could be lost or garbled ---> time-out mechanism for the sender Problem: ---> How long is timeout? ---> Early time-out ---> synchronization problem! Solution approach: Having sliding window protocols were each outbound frame contains a sequence number ---> sender (receiver) maintains a set of sequence numbers up to some maximum 2 n -1, called sending (receiving) window, corresponding to frames it is permitted to send (accept) Illustration of the main idea of sliding windows (maximum window size = 1, n = 3 ---> 3-bit sequence number)

15 Data Link Layer(15) One Bit Sliding Window Protocol (Stop-and-Wait) Ack field contains the number of the last frame received without error Agreement with the number of the frame being sent ---> fetch the next frame from the network layer No agreement ---> continue trying to send the same frame Whenever a frame is received, a frame is also sent back Example Resulting Quality of Service No delivering of duplicate packets to either network layer No packet is skipped No deadlock

16 Data Link Layer(16) Implicit assumption so far: Transmission times for a data frame + its ack are negligible If this assumption is false ---> exploitation of the bandwidth may be disastrous ---> In such a case, requiring a sender to wait for an ack before sending the next frame must be relaxed Pipelining The sender is allowed to transmit up to w frames before blocking, instead of just 1. Remaining problem: What happens if a frame is lost or damaged in the middle of a long stream of transmitted frames? A protocol using go back n All frames arriving after an erroneous one are simply discarded ---> the data link layer refuses to accept any frame except the next one to be delivered to the network layer ---> eventually, the sender will time out and retransmit all unacknowledged frames in order starting with the erroneous one This strategy corresponds to a receive window of size 1.

17 Data Link Layer(17) Example: Main drawback: It can waste a lot of bandwidth if the error rate is high A protocol using selective repeat All correct frames arriving after an erroneous one are accepted by the receiver Example: This strategy corresponds to a receive window of size > 1. Main drawback: It can require large amounts of data link layer buffer space

18 Data Link Layer(18) Pipelining implies multiple outstanding frames. ---> Each frame times out independent of all the other ones ---> It logically needs multiple timers Simulation of multiple timers in software using a single hardware clock The pending timeouts form a linked list Example:

19 Internet protocols for the Data Link Layer Data Link Layer(13) Two protocols, SLIP and PPP, are widely used in the Internet as point-to-point data link protocols. Typical application example: A home PC acting as an Internet host

20 Data Link Layer(14) The Serial Line Internet Protocol (SLIP): Designed in 1984 to connect SUN workstations to the Internet over a dial-up line using a modem. It is very simple: sends raw IP packets over the line with a special flag byte at the end for framing uses some form of character stuffing Drawbacks: does not do any error detection or correction supports only IP each side must know the other s IP address a priori does not provide any form of authentication no approved Internet Standard

21 Data Link Layer(15) The Point-to-Point Protocol (PPP): PPP basically provides three things: 1. A framing method that unambiguously delineates the end of one frame and the start of the next one. The frame format also handles error detection. 2. A link control protocol for bringing lines up, testing them, negotiating options, and bringing them down again gracefully when they are no longer needed. This protocol is called LCP (Link Control Protocol). 3. A way to negotiate network-layer options in a way that is independent of the network layer protocol to be used. The method chosen is to have a different NCP (Network Control Protocol) for each network layer supported.

22 Data Link Layer(16) A simplified phase diagram for bringing a line up and down: The PPP full frame format for unnumbered mode of operation:

### Computer Networks. Data Link Layer

Computer Networks The Data Link Layer 1 Data Link Layer Application Transport Network DLL PHY 2 What does it do? What functions it performs? Typically: Handling transmission errors, a.k.a., error control.

### Chapter 3: Sample Questions, Problems and Solutions Bölüm 3: Örnek Sorular, Problemler ve Çözümleri

Chapter 3: Sample Questions, Problems and Solutions Bölüm 3: Örnek Sorular, Problemler ve Çözümleri Örnek Sorular (Sample Questions): What is an unacknowledged connectionless service? What is an acknowledged

### CMPE 150 Winter 2009

CMPE 150 Winter 2009 Lecture 6 January 22, 2009 P.E. Mantey CMPE 150 -- Introduction to Computer Networks Instructor: Patrick Mantey mantey@soe.ucsc.edu http://www.soe.ucsc.edu/~mantey/ / t / Office: Engr.

Data Link Layer Overview Date link layer deals with two basic issues: Part I How data frames can be reliably transmitted, and Part II How a shared communication medium can be accessed In many networks,

High-Level Data Link Control This class of data link layer protocols includes High-level Data Link Control (HDLC), Link Access Procedure Balanced (LAPB) for X.25, Link Access Procedure for D-channel (LAPD)

### LLC: Frame Construction. Layer 2: Division into two Parts. Error-detecting and -correcting Codes. Error-correcting Codes

Sicherungsebene Layer 2: Division into two Parts Logical Link Control (LLC) (Layer 2b) Organization of the data to be sent into frames Guarantee (if possible) an error free transmission between neighboring

### Stop And Wait. ACK received; transmit frame 2 CS 455 3

Data Link Layer, Part 5 Sliding Window Protocols 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

### Data Link Layer. Flow Control. Flow Control

Data Link Layer Flow Control 1 Flow Control Flow Control is a technique for speed-matching of transmitter and receiver. Flow control ensures that a transmitting station does not overflow a receiving station

### Sheet 7 (Chapter 10)

King Saud University College of Computer and Information Sciences Department of Information Technology CAP240 First semester 1430/1431 Multiple-choice Questions Sheet 7 (Chapter 10) 1. Which error detection

### Transport Layer Protocols

Transport Layer Protocols Version. Transport layer performs two main tasks for the application layer by using the network layer. It provides end to end communication between two applications, and implements

### CSE331: Introduction to Networks and Security. Lecture 9 Fall 2006

CSE33: Introduction to Networks and Security Lecture 9 Fall 2006 Announcements Project Due TODAY HW Due on Friday Midterm I will be held next Friday, Oct. 6th. Will cover all course material up to next

### SLIP and PPP. Gursharan Singh Tatla. mailme@gursharansingh.in www.eazynotes.com. 1 www.eazynotes.com

SLIP and PPP Gursharan Singh Tatla mailme@gursharansingh.in 1 Data Link Layer in Internet We know that Internet consists of individual systems that are connected to each other. Basically, it is wide are

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

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

### Computer Networks. Chapter 5 Transport Protocols

Computer Networks Chapter 5 Transport Protocols Transport Protocol Provides end-to-end transport Hides the network details Transport protocol or service (TS) offers: Different types of services QoS Data

### Data Link Protocols. 5.4 Framing

Data Link Protocols A Packets Data link layer Physical layer Frames Packets Data link layer Physical layer B Data Links Services Framing Error control Flow control Multiplexing Link Maintenance Security:

### Module 1. Introduction. Version 2 CSE IIT, Kharagpur

Module 1 Introduction Lesson 2 Layered Network Architecture Specific Functional Objectives On Completion of this lesson, the students will be able to: State the requirement for layered approach Explain

### Protocols and Architecture. Protocol Architecture.

Protocols and Architecture Protocol Architecture. Layered structure of hardware and software to support exchange of data between systems/distributed applications Set of rules for transmission of data between

### Written examination in Computer Networks

Written examination in Computer Networks February 14th 2014 Last name: First name: Student number: Provide on all sheets (including the cover sheet) your last name, rst name and student number. Use the

### EE4367 Telecom. Switching & Transmission. Prof. Murat Torlak

Packet Switching and Computer Networks Switching As computer networks became more pervasive, more and more data and also less voice was transmitted over telephone lines. Circuit Switching The telephone

### Error detection using CRC

Error detection using CRC The goal of this task is to become familiar with functional principles of CRC (Cyclic Redundancy Check): - math background - error detection features - practical implementation

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

### [Prof. Rupesh G Vaishnav] Page 1

Basics The function of transport layer is to provide a reliable end-to-end communications service. It also provides data transfer service for the user layers above and shield the upper layers from the

### Applied Data Communication Lecture 14

Applied Data Communication Lecture 14 Character oriented Data Link Character-oriented data link control Asynchronous Synchronous Kristjan Sillmann reaalajasüsteemide õppetool TTÜ automaatikainstituut character-oriented

### ESSENTIALS. Understanding Ethernet Switches and Routers. April 2011 VOLUME 3 ISSUE 1 A TECHNICAL SUPPLEMENT TO CONTROL NETWORK

VOLUME 3 ISSUE 1 A TECHNICAL SUPPLEMENT TO CONTROL NETWORK Contemporary Control Systems, Inc. Understanding Ethernet Switches and Routers This extended article was based on a two-part article that was

### Guide to TCP/IP, Third Edition. Chapter 3: Data Link and Network Layer TCP/IP Protocols

Guide to TCP/IP, Third Edition Chapter 3: Data Link and Network Layer TCP/IP Protocols Objectives Understand the role that data link protocols, such as SLIP and PPP, play for TCP/IP Distinguish among various

### COMPUTER NETWORKS REVIEW QUESTIONS AND PROBLEMS

COMPUTER NETWORKS REVIEW QUESTIONS AND PROBLEMS. INTRODUCTION TO COMPUTER NETWORKS. What is a computer network? Briefly define..2 Briefly define the client-server model..3 What is scalability? Briefly

### Ethernet. Ethernet. Network Devices

Ethernet Babak Kia Adjunct Professor Boston University College of Engineering ENG SC757 - Advanced Microprocessor Design Ethernet Ethernet is a term used to refer to a diverse set of frame based networking

### 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

### Operating Systems and Computer Networks / Datenverarbeitung 2 / Data Processing 2

Computer Networks / Datenverarbeitung 2 / Data Processing 2 Exercise 7: Network Transmission & Code Efficiency Faculty of Question 7.1 Code Efficiency Block Length S S S Y Y O N N H 5 characters S T X

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

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

### Computer Network. Interconnected collection of autonomous computers that are able to exchange information

Introduction Computer Network. Interconnected collection of autonomous computers that are able to exchange information No master/slave relationship between the computers in the network Data Communications.

### DATA COMMUNICATION AND NETWORKS

DATA COMMUNICATION AND NETWORKS 1. Define the term Computer Networks. A Computer network is a number if computers interconnected by one or more transmission paths. The transmission path often is the telephone

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

LAN Switching 15-441 Computer Networking Bridges/Switches, 802.11, PPP Extend reach of a single shared medium Connect two or more segments by copying data frames between them Switches only copy data when

### TCP over Multi-hop Wireless Networks * Overview of Transmission Control Protocol / Internet Protocol (TCP/IP) Internet Protocol (IP)

TCP over Multi-hop Wireless Networks * Overview of Transmission Control Protocol / Internet Protocol (TCP/IP) *Slides adapted from a talk given by Nitin Vaidya. Wireless Computing and Network Systems Page

### 3.4 SLIDING WINDOW PROTOCOLS

SEC. 3.3 SLIDING WINDOW PROTOCOLS 211 3.4 SLIDING WINDOW PROTOCOLS In the previous protocols, data frames were transmitted in one direction only. In most practical situations, there is a need for transmitting

### B-2 Analyzing TCP/IP Networks with Wireshark. Ray Tompkins Founder of Gearbit www.gearbit.com

B-2 Analyzing TCP/IP Networks with Wireshark June 15, 2010 Ray Tompkins Founder of Gearbit www.gearbit.com SHARKFEST 10 Stanford University June 14-17, 2010 TCP In this session we will examine the details

### Process Control and Automation using Modbus Protocol

Process Control and Automation using Modbus Protocol Modbus is the fundamental network protocol used in most industrial applications today. It is universal, open and an easy to use protocol. Modbus has

### Access Control: Firewalls (1)

Access Control: Firewalls (1) World is divided in good and bad guys ---> access control (security checks) at a single point of entry/exit: in medieval castles: drawbridge in corporate buildings: security/reception

### Names & Addresses. Names & Addresses. Hop-by-Hop Packet Forwarding. Longest-Prefix-Match Forwarding. Longest-Prefix-Match Forwarding

Names & Addresses EE 122: IP Forwarding and Transport Protocols Scott Shenker http://inst.eecs.berkeley.edu/~ee122/ (Materials with thanks to Vern Paxson, Jennifer Rexford, and colleagues at UC Berkeley)

### Lecture Objectives. Lecture 07 Mobile Networks: TCP in Wireless Networks. Agenda. TCP Flow Control. Flow Control Can Limit Throughput (1)

Lecture Objectives Wireless and Mobile Systems Design Lecture 07 Mobile Networks: TCP in Wireless Networks Describe TCP s flow control mechanism Describe operation of TCP Reno and TCP Vegas, including

### Subnetting,Supernetting, VLSM & CIDR

Subnetting,Supernetting, VLSM & CIDR WHAT - IP Address Unique 32 or 128 bit Binary, used to identify a system on a Network or Internet. Network Portion Host Portion CLASSFULL ADDRESSING IP address space

### Review of Error Detection of Data Link Layer in Computer Network

Middle-East Journal of Scientific Research 18 (8): 1105-1110, 2013 ISSN 1990-9233 IDOSI Publications, 2013 DOI: 10.5829/idosi.mejsr.2013.18.8.11835 Review of Error Detection of Data Link Layer in Computer

### Appendix B RCS11 Remote Communications

Appendix B RCS11 Remote Communications B.1 Host Computer Remote Communications Control and status messages are conveyed between the RCS11 and the host computer using packetized message blocks in accordance

### 15-441: Computer Networks Homework 2 Solution

5-44: omputer Networks Homework 2 Solution Assigned: September 25, 2002. Due: October 7, 2002 in class. In this homework you will test your understanding of the TP concepts taught in class including flow

### CYCLIC REDUNDANCY CHECKS IN USB. Introduction. Two-minute mathematical background

CYCLIC REDUNDANCY CHECKS IN USB Introduction The USB specification calls for the use of Cyclic Redundancy Checksums (CRC) to protect all non-pid fields in token and data packets from errors during transmission.

### 1. The subnet must prevent additional packets from entering the congested region until those already present can be processed.

Congestion Control When one part of the subnet (e.g. one or more routers in an area) becomes overloaded, congestion results. Because routers are receiving packets faster than they can forward them, one

### A Transport Protocol for Multimedia Wireless Sensor Networks

A Transport Protocol for Multimedia Wireless Sensor Networks Duarte Meneses, António Grilo, Paulo Rogério Pereira 1 NGI'2011: A Transport Protocol for Multimedia Wireless Sensor Networks Introduction Wireless

### Quectel Cellular Engine

Cellular Engine GSM Multiplexer Application Notes GSM_MUX_AN_V1.00 Document Title GSM Multiplexer Application Notes Version 1.00 Date 2009-06-27 Status Document Control ID Release GSM_MUX_AN_V1.00 General

### Network Simulation Traffic, Paths and Impairment

Network Simulation Traffic, Paths and Impairment Summary Network simulation software and hardware appliances can emulate networks and network hardware. Wide Area Network (WAN) emulation, by simulating

### 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

### Lab Exercise 802.11. Objective. Requirements. Step 1: Fetch a Trace

Lab Exercise 802.11 Objective To explore the physical layer, link layer, and management functions of 802.11. It is widely used to wireless connect mobile devices to the Internet, and covered in 4.4 of

### Link Layer. 5.6 Hubs and switches 5.7 PPP 5.8 Link Virtualization: ATM and MPLS

Link Layer 5.1 Introduction and services 5.2 Error detection and correction 5.3Multiple access protocols 5.4 Link-Layer Addressing 5.5 Ethernet 5.6 Hubs and switches 5.7 PPP 5.8 Link Virtualization: and

### Chapter 9. IP Secure

Chapter 9 IP Secure 1 Network architecture is usually explained as a stack of different layers. Figure 1 explains the OSI (Open System Interconnect) model stack and IP (Internet Protocol) model stack.

### Mathematical Modelling of Computer Networks: Part II. Module 1: Network Coding

Mathematical Modelling of Computer Networks: Part II Module 1: Network Coding Lecture 3: Network coding and TCP 12th November 2013 Laila Daniel and Krishnan Narayanan Dept. of Computer Science, University

### TCP in Wireless Mobile Networks

TCP in Wireless Mobile Networks 1 Outline Introduction to transport layer Introduction to TCP (Internet) congestion control Congestion control in wireless networks 2 Transport Layer v.s. Network Layer

### ICOM 5026-090: Computer Networks Chapter 6: The Transport Layer. By Dr Yi Qian Department of Electronic and Computer Engineering Fall 2006 UPRM

ICOM 5026-090: Computer Networks Chapter 6: The Transport Layer By Dr Yi Qian Department of Electronic and Computer Engineering Fall 2006 Outline The transport service Elements of transport protocols A

### A Layered Approach to Computer Networks

A Layered Approach to Computer Networks Physical Layer Data Link Layer Network Layer Transport Layer Session Layer Presentation Layer Application Layer Different layer of abstraction Different error control

### point to point and point to multi point calls over IP

Helsinki University of Technology Department of Electrical and Communications Engineering Jarkko Kneckt point to point and point to multi point calls over IP Helsinki 27.11.2001 Supervisor: Instructor:

### Ring Local Area Network. Ring LANs

Ring Local Area Network Ring interface (1-bit buffer) Ring interface To station From station Ring LANs The ring is a series of bit repeaters, each connected by a unidirectional transmission link All arriving

### The finite field with 2 elements The simplest finite field is

The finite field with 2 elements The simplest finite field is GF (2) = F 2 = {0, 1} = Z/2 It has addition and multiplication + and defined to be 0 + 0 = 0 0 + 1 = 1 1 + 0 = 1 1 + 1 = 0 0 0 = 0 0 1 = 0

### Computer Networks UDP and TCP

Computer Networks UDP and TCP Saad Mneimneh Computer Science Hunter College of CUNY New York I m a system programmer specializing in TCP/IP communication protocol on UNIX systems. How can I explain a thing

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

Ethernet dominant LAN technology: cheap -- \$20 for 100Mbs! first widely used LAN technology Simpler, cheaper than token rings and ATM Kept up with speed race: 10, 100, 1000 Mbps Metcalfe s Etheret sketch

### Protocol Security Where?

IPsec: AH and ESP 1 Protocol Security Where? Application layer: (+) easy access to user credentials, extend without waiting for OS vendor, understand data; (-) design again and again; e.g., PGP, ssh, Kerberos

### Dynamic Source Routing in Ad Hoc Wireless Networks

Dynamic Source Routing in Ad Hoc Wireless Networks David B. Johnson David A. Maltz Computer Science Department Carnegie Mellon University 5000 Forbes Avenue Pittsburgh, PA 15213-3891 dbj@cs.cmu.edu Abstract

### Lecture 15: Congestion Control. CSE 123: Computer Networks Stefan Savage

Lecture 15: Congestion Control CSE 123: Computer Networks Stefan Savage Overview Yesterday: TCP & UDP overview Connection setup Flow control: resource exhaustion at end node Today: Congestion control Resource

### IP - The Internet Protocol

Orientation IP - The Internet Protocol IP (Internet Protocol) is a Network Layer Protocol. IP s current version is Version 4 (IPv4). It is specified in RFC 891. TCP UDP Transport Layer ICMP IP IGMP Network

### RS-485 Protocol Manual

RS-485 Protocol Manual Revision: 1.0 January 11, 2000 RS-485 Protocol Guidelines and Description Page i Table of Contents 1.0 COMMUNICATIONS BUS OVERVIEW... 1 2.0 DESIGN GUIDELINES... 1 2.1 Hardware Design

### GATE CS Topic wise Questions Computer Network

www.gatehelp.com GATE CS Topic wise Questions YEAR 23 Question. 1 Which of the following assertions is false about the internet Protocol (IP)? (A) It is possible for a computer to have multiple IP addresses

### Protocols. Packets. What's in an IP packet

Protocols Precise rules that govern communication between two parties TCP/IP: the basic Internet protocols IP: Internet Protocol (bottom level) all packets shipped from network to network as IP packets

### ECE 333: Introduction to Communication Networks Fall 2002

ECE 333: Introduction to Communication Networks Fall 2002 Lecture 14: Medium Access Control II Dynamic Channel Allocation Pure Aloha In the last lecture we began discussing medium access control protocols

### LIN (Local Interconnect Network):

LIN (Local Interconnect Network): History: LIN (Local Interconnect Network) was developed as cost-effective alternate to CAN protocol. In 1998 a group of companies including Volvo, Motorola, Audi, BMW,

### Overview. Securing TCP/IP. Introduction to TCP/IP (cont d) Introduction to TCP/IP

Overview Securing TCP/IP Chapter 6 TCP/IP Open Systems Interconnection Model Anatomy of a Packet Internet Protocol Security (IPSec) Web Security (HTTP over TLS, Secure-HTTP) Lecturer: Pei-yih Ting 1 2

### DATA COMMUNICATIONS AND NETWORKING. Solved Examples

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

### PPP (Point-to-Point Protocol)

PPP (Point-to-Point Protocol) PPP (Point-to-Point Protocol) is the most widely used method for transporting IP packets over a serial link between the user and the Internet Service Provider (ISP). Although

### Virtual Integrated Design Getting started with RS232 Hex Com Tool v6.0

Virtual Integrated Design Getting started with RS232 Hex Com Tool v6.0 Copyright, 1999-2007 Virtual Integrated Design, All rights reserved. 1 Contents: 1. The Main Window. 2. The Port Setup Window. 3.

### PROPERTY MANAGEMENT SYSTEM

PROPERTY MANAGEMENT SYSTEM COMMUNICATION INTERFACE SPECIFICATION NEC America, Inc. NDA-305-00 Revision.0 June, 998 Stock # 24727 LIABILITY DISCLAIMER NEC America reserves the right to change the specifications,

### OSI Model. Application Presentation Session Transport Network Data Link Physical. EE156 Computer Network Architecture

OSI Model 7 6 5 4 3 2 1 Application Presentation Session Transport Network Data Link Physical Protocols Define a set of rules for communication. Specify the meaning and format of messages Define exchange

### BCS THE CHARTERED INSTITUTE FOR IT. BCS HIGHER EDUCATION QUALIFICATIONS BCS Level 5 Diploma in IT COMPUTER NETWORKS

BCS THE CHARTERED INSTITUTE FOR IT BCS HIGHER EDUCATION QUALIFICATIONS BCS Level 5 Diploma in IT COMPUTER NETWORKS Friday 2 nd October 2015 Morning Answer any FOUR questions out of SIX. All questions carry

### PRODUCT MANUAL SKX OPEN SKX ADVANCE ZN1RX-SKXOPEN. Edition 2 Version 1.1

PRODUCT MANUAL SKX OPEN SKX ADVANCE ZN1RX-SKXOPEN Edition 2 Version 1.1 INDEX 1. Introduction... 3 1.1. SKX Interface... 3 1.2. SKX Installation... 5 1.3. SKX Advance: Application Program... 5 1.3.1. SKX

### 15-441: Computer Networks Homework 1

15-441: Computer Networks Homework 1 Assigned: January 29, 2008 Due: February 7, 2008 1. Suppose a 100-Mbps point-to-point link is being set up between Earth and a new lunar colony. The distance from the

### R2. The word protocol is often used to describe diplomatic relations. How does Wikipedia describe diplomatic protocol?

Chapter 1 Review Questions R1. What is the difference between a host and an end system? List several different types of end systems. Is a Web server an end system? 1. There is no difference. Throughout

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

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

### Midterm Exam CMPSCI 453: Computer Networks Fall 2011 Prof. Jim Kurose

Midterm Exam CMPSCI 453: Computer Networks Fall 2011 Prof. Jim Kurose Instructions: There are 4 questions on this exam. Please use two exam blue books answer questions 1, 2 in one book, and the remaining

### Fast Ethernet and Gigabit Ethernet. Networks: Fast Ethernet 1

Fast Ethernet and Gigabit Ethernet Networks: Fast Ethernet 1 Fast Ethernet (100BASE-T) How to achieve 100 Mbps capacity? MII LLC MAC Convergence Sublayer Media Independent Interface Media Dependent Sublayer

### IP Network Layer. Datagram ID FLAG Fragment Offset. IP Datagrams. IP Addresses. IP Addresses. CSCE 515: Computer Network Programming TCP/IP

CSCE 515: Computer Network Programming TCP/IP IP Network Layer Wenyuan Xu Department of Computer Science and Engineering University of South Carolina IP Datagrams IP is the network layer packet delivery

### A NOVEL RESOURCE EFFICIENT DMMS APPROACH

A NOVEL RESOURCE EFFICIENT DMMS APPROACH FOR NETWORK MONITORING AND CONTROLLING FUNCTIONS Golam R. Khan 1, Sharmistha Khan 2, Dhadesugoor R. Vaman 3, and Suxia Cui 4 Department of Electrical and Computer

### Internetworking. Problem: There is more than one network (heterogeneity & scale)

Internetworking Problem: There is more than one network (heterogeneity & scale) Hongwei Zhang http://www.cs.wayne.edu/~hzhang Internetworking: Internet Protocol (IP) Routing and scalability Group Communication

### AN ANALYSIS OF DELAY OF SMALL IP PACKETS IN CELLULAR DATA NETWORKS

AN ANALYSIS OF DELAY OF SMALL IP PACKETS IN CELLULAR DATA NETWORKS Hubert GRAJA, Philip PERRY and John MURPHY Performance Engineering Laboratory, School of Electronic Engineering, Dublin City University,

### Voice Over IP Per Call Bandwidth Consumption

Over IP Per Call Bandwidth Consumption Interactive: This document offers customized voice bandwidth calculations with the TAC Bandwidth Calculator ( registered customers only) tool. Introduction Before

### Single channel data transceiver module WIZ2-434

Single channel data transceiver module WIZ2-434 Available models: WIZ2-434-RS: data input by RS232 (±12V) logic, 9-15V supply WIZ2-434-RSB: same as above, but in a plastic shell. The WIZ2-434-x modules

### ARM Thumb Microcontrollers. Application Note. Software ISO 7816 I/O Line Implementation. Features. Introduction

Software ISO 7816 I/O Line Implementation Features ISO 7816-3 compliant (direct convention) Byte reception and transmission with parity check Retransmission on error detection Automatic reception at the

### Communications and Computer Networks

SFWR 4C03: Computer Networks and Computer Security January 5-8 2004 Lecturer: Kartik Krishnan Lectures 1-3 Communications and Computer Networks The fundamental purpose of a communication system is the

### Channel Bonding in DOCSIS 3.0. Greg White Lead Architect Broadband Access CableLabs

Channel Bonding in DOCSIS 3.0 Greg White Lead Architect Broadband Access CableLabs Agenda DS Channel Bonding Protocol Receive Channel Profiles US Channel Bonding Protocol HFC Plant Topologies & Resolution

### Simulation-Based Comparisons of Solutions for TCP Packet Reordering in Wireless Network

Simulation-Based Comparisons of Solutions for TCP Packet Reordering in Wireless Network 作 者 :Daiqin Yang, Ka-Cheong Leung, and Victor O. K. Li 出 處 :Wireless Communications and Networking Conference, 2007.WCNC

### Implementing and testing tftp

CSE123 Spring 2013 Term Project Implementing and testing tftp Project Description Checkpoint: May 10, 2013 Due: May 29, 2013 For this project you will program a client/server network application in C on

### A DNP3 Protocol Primer

A Protocol Primer Introduction This is a primer for people who want a quick understanding of without having to comb through the tedious details of a complex specification. The writing style is meant to

### 3. MONITORING AND TESTING THE ETHERNET NETWORK

3. MONITORING AND TESTING THE ETHERNET NETWORK 3.1 Introduction The following parameters are covered by the Ethernet performance metrics: Latency (delay) the amount of time required for a frame to travel