This document summarizes a lecture on computer networks and error control. It discusses topics like Hamming codes, cyclic redundancy checks (CRCs), stop-and-wait protocols, automatic repeat request (ARQ) protocols, and sliding window protocols. The reading assignment is chapter 3 of the Tanenbaum textbook and the lecture will cover error control, error and flow control, and how layer 2 protocols implement these functions using frames, headers, trailers, and checksums.
A computer network is network of computer .It connects multiple computer in manner to enable meaningful transmission and exchange of data among them.Main objective of CN is sharing of information ,resources and processing load among the connected computer.
you can easily get basic introduction of COMPUTER NETWORK
A computer network is network of computer .It connects multiple computer in manner to enable meaningful transmission and exchange of data among them.Main objective of CN is sharing of information ,resources and processing load among the connected computer.
you can easily get basic introduction of COMPUTER NETWORK
What is a network?
Need for networking
Components of Network
Types of Network
Evolution of Networking
Communication media
Data Communication Terminologies
Switching Techniques
Digital and Analog Transmission
Network Topology
Network Devices
Communication Protocols
Wireless/Mobile Computing
Data communication and computer networks | Network TopologiesMSA Technosoft
This video tutorial is all about Data Communication & Computer Network. In this video we have covered several networking topics:
Data Communication, Computer Networks, Network Topologies, Components of Data Communication, Mode of Data flow, Type of Connection, point-to-point connection, multipoint connection, Physical topology, Logical Topology, Mesh Topology, Bus Topology, Ring Topology, Star Topology, Hybrid Topology, LAN Topologies, WAN Topologies, Daisy Chains, Hierarchies, Switched Topologies, Token passing, Three-Tiered WAN, Two-Tiered WAN, Categories of Networks, Internet, Protocol and Standards
For more details visit our Tech Blog:
https://msatechnosoft.in/blog/
COMPUTER NETWORKING SUCH AS- DATA TRANSMISSION,
OVERVIEW OF COMPUTER NETWORKING,
TYPES OF NETWORK & TOPOLOGIES &
PACKET TRANSMISSION
INTERNET & INTRANET INCLUDED-
INTRODUCTION
OVERVIEW OF INTERNET
ARCHITECTURE & FUNCTIONING OF INTERNET
WEB PAGE, HTML
BASIC SERVICES OVER INTERNET
Basics of Computer Communication and Network with Emphasis on the history of communication. It also mentions the current scenario of computer networks.
What is a network?
Need for networking
Components of Network
Types of Network
Evolution of Networking
Communication media
Data Communication Terminologies
Switching Techniques
Digital and Analog Transmission
Network Topology
Network Devices
Communication Protocols
Wireless/Mobile Computing
Data communication and computer networks | Network TopologiesMSA Technosoft
This video tutorial is all about Data Communication & Computer Network. In this video we have covered several networking topics:
Data Communication, Computer Networks, Network Topologies, Components of Data Communication, Mode of Data flow, Type of Connection, point-to-point connection, multipoint connection, Physical topology, Logical Topology, Mesh Topology, Bus Topology, Ring Topology, Star Topology, Hybrid Topology, LAN Topologies, WAN Topologies, Daisy Chains, Hierarchies, Switched Topologies, Token passing, Three-Tiered WAN, Two-Tiered WAN, Categories of Networks, Internet, Protocol and Standards
For more details visit our Tech Blog:
https://msatechnosoft.in/blog/
COMPUTER NETWORKING SUCH AS- DATA TRANSMISSION,
OVERVIEW OF COMPUTER NETWORKING,
TYPES OF NETWORK & TOPOLOGIES &
PACKET TRANSMISSION
INTERNET & INTRANET INCLUDED-
INTRODUCTION
OVERVIEW OF INTERNET
ARCHITECTURE & FUNCTIONING OF INTERNET
WEB PAGE, HTML
BASIC SERVICES OVER INTERNET
Basics of Computer Communication and Network with Emphasis on the history of communication. It also mentions the current scenario of computer networks.
Networks must be able to transfer data from one device to another with acceptable
accuracy. For most applications, a system must guarantee that the data received are
identical to the data transmitted. Any time data are transmitted from one node to the
next, they can become corrupted in passage. Many factors can alter one or more bits of
a message. Some applications require a mechanism for detecting and correcting errors.
Some applications can tolerate a small level of error. For example, random errors
in audio or video transmissions may be tolerable, but when we transfer text, we expect
a very high level of accuracy.
At the data-link layer, if a frame is corrupted between the two nodes, it needs to be
corrected before it continues its journey to other nodes. However, most link-layer protocols
simply discard the frame and let the upper-layer protocols handle the retransmission
of the frame. Some multimedia applications, however, try to correct the corrupted frame.
This chapter is divided into five sections.
❑ The first section introduces types of errors, the concept of redundancy, and distinguishes
between error detection and correction.
❑ The second section discusses block coding. It shows how error can be detected
using block coding and also introduces the concept of Hamming distance.
❑ The third section discusses cyclic codes. It discusses a subset of cyclic code, CRC,
that is very common in the data-link layer. The section shows how CRC can be
easily implemented in hardware and represented by polynomials.
❑ The fourth section discusses checksums. It shows how a checksum is calculated for
a set of data words. It also gives some other approaches to traditional checksum.
❑ The fifth section discusses forward error correction. It shows how Hamming distance
can also be used for this purpose. The section also describes cheaper methods
to achieve the same goal, such as XORing of packets, interleaving chunks, or
compounding high and low resolutions packets.
XPDS13: On Paravirualizing TCP - Congestion Control on Xen VMs - Luwei Cheng,...The Linux Foundation
While datacenters are increasingly adopting VMs to provide elastic cloud services, they still rely on traditional TCP for congestion control. In this talk, I will first show that VM scheduling delays can heavily contaminate RTTs sensed by VM senders, preventing TCP from correctly learning the physical network condition. Focusing on the incast problem, which is commonly seen in large-scale distributed data processing such as MapReduce and web search, I find that the solutions that have been developed for *physical* clusters fall short in a Xen *virtual* cluster. Second, I will provide a concrete understanding of the problem, and reveal that the situations that when the sending VM is preempted versus when the receiving VM is preempted, are different. Third, I will introduce my recent attempts on paravirtualizing TCP to overcome the negative effect caused by VM scheduling delays.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Unit 8 - Information and Communication Technology (Paper I).pdf
Introduction to Computer Networks
1. 1CMPE 150- Introduction to Computer Networks
CMPE 150
Fall 2005
Lecture 12
Introduction to Computer
Networks
2. 2CMPE 150- Introduction to Computer Networks
Announcements
• TA office hours this week.
– Instead of tomorrow, they will be held Friday
1-2pm at E2 315.
• Book should be on reserve at S&E Library.
3. 3CMPE 150- Introduction to Computer Networks
Last Class
• Layer 2 (Cont’d).
– Mechanisms for error control: ACKs/NACKs,
retransmissions, timers, etc.
– Flow control.
• Flow- versus congestion control.
• Types of flow control.
– Error detection and correction.
• Trade-offs.
• Hamming distance.
• Error detection mechanisms and examples.
• Error correction mechanisms and examples.
7. 7CMPE 150- Introduction to Computer Networks
Hamming Code
• Bits in positions that are power of 2 are check
bits. The rest are data bits.
• Each check bit used in parity (even or odd)
computation of collection of bits.
– Example: check bit in position 11, checks for
bits in positions, 11 = 1+2+8. Similarly, bit 11
is checked by bits 1, 2, and 8.
8. 8CMPE 150- Introduction to Computer Networks
Hamming Code: Example
7-bit
. Hamming codes can only correct single errors.
. But, to correct bursts of errors, send column by column.
9. 9CMPE 150- Introduction to Computer Networks
Error Detecting Codes
• Typically used in reliable media.
• Examples: parity bit, polynomial codes (a.k.a.,
CRC, or Cyclic redundancy Check).
10. 10CMPE 150- Introduction to Computer Networks
Polynomial Codes
• Treat bit strings as representations of
polynomials with coefficients 1’s and 0’s.
• K-bit frame is coefficient list of polynomial
with k terms (and degree k-1), from xk-1
to x0
.
– Highest-order bit is coefficient of xk-1
, etc.
– Example: 110001 represents x5
+ x4
+x0
.
• Generator polynomial G(x).
– Agreed upon by sender and receiver.
11. 11CMPE 150- Introduction to Computer Networks
CRC
• Checksum appended to frame being
transmitted.
– Resulting polynomial divisible by G(x).
• When receiver gets checksummed frame, it
divides it by G(x).
– If remainder, then error!
13. 13CMPE 150- Introduction to Computer Networks
Cyclic Redunancy Check
At Transmitter, with M = 1 1 1 0 1 1, compute
2r
M= 1 1 1 0 1 1 0 0 0 with G = 1 1 0 1
T = 2r
M + R [note G starts and ends with “1” ]
R = 1 1 1
Transmit T= 1 1 1 0 1 1 1 1 1
14. 14CMPE 150- Introduction to Computer Networks
Cyclic Redundancy Check
At the Receiver, compute:
Note remainder = 0 no errors detected
15. 15CMPE 150- Introduction to Computer Networks
CRC Performance
• Errors go through undetected only if divisible
by G(x)
• With “suitably chosen” G(x) CRC code detects
all single-bit errors.
• And more…
17. 17CMPE 150- Introduction to Computer Networks
Flow + Error Control
• How do Layer 2 protocols implement them?
• What’s a frame?
F FH TPayload
. What’s F?
. What’s in T?
. What’s in H?
18. 18CMPE 150- Introduction to Computer Networks
Header and Trailer
• Trailer typically has checksum.
– How is it used/processed?
• Header has: type, sequence number, and
ack.
19. 19CMPE 150- Introduction to Computer Networks
Stop-and-Wait
• Simplest form of flow control.
• How does it work? (assume error-free
channel)
– (1) Send 1 frame;
– (2) Wait for ACK.
– (3) Go to 1.
20. 20CMPE 150- Introduction to Computer Networks
Stop-and-Wait: Pros and
Cons
• Very simple!
• But, poor link utilization.
– High data rates.
– Long propagation delay.
21. 21CMPE 150- Introduction to Computer Networks
Noisy Channels
From Stallings: Data and Computer
Communications
22. 22CMPE 150- Introduction to Computer Networks
Stop-and-Wait in Noisy
Channels
• Need timers, retransmissions, and duplicate
detection.
• Use sequence numbers.
– Why?
– Distinguish frames.
– How large (e.g., in number of bits) are
sequence numbers?
23. 23CMPE 150- Introduction to Computer Networks
ARQ Protocols
• Automatic Repeat Request.
– Protocols that wait for ACK before sending
more data.
• ACKs now are used for flow AND error
control.
• What can happen?
– At receiver: frame arrives correctly, frame
arrives damaged, frame does not arrive.
– At sender: ACK arrives correctly, ACK arrives
damaged, ACK does not arrive.
24. 24CMPE 150- Introduction to Computer Networks
ARQ Protocols
• Sender:
– Send frame 0.
– Start timer.
– If ACK 0, arrives, send
frame 1.
– If timeout, re-send
frame 0.
• Receiver:
– **Waits for frame.
– If frame arrives, check
if correct sequence
number.
– Then send ACK for
that frame.
– Go to (**)
25. 25CMPE 150- Introduction to Computer Networks
Simplex versus Duplex
Transmission
• Simplex:
– Send data in one channel and control in
another channel.
• Duplex:
– Send data and control on the same chanel.
26. 26CMPE 150- Introduction to Computer Networks
Can we do better?
• Can we do better?
– Piggybacking.
– Bi-directional transmission.
– Wait for data packet and use that to piggyback
the ACK.
– Use ACK field: only a few additional bits in the
header.
• But, how long should Layer 2 wait to send an
ACK?
– ACK timers!
27. 27CMPE 150- Introduction to Computer Networks
Sliding Window Protocols
• Window: number of “outstanding” frames at
any given point in time.
• Every ACK received, window slides…
28. 28CMPE 150- Introduction to Computer Networks
Sliding Window Example
• A sliding window of size 1, with a 3-bit sequence
number.(a) Initially; (b) After the first frame has
been sent; (c) After the first frame has been
received;(d) After the first acknowledgement has
been received.