Abstract The data can get lost, reordered or duplicated due to the presence of routers and buffer space over the unreliable channel in the conventional networks. The data link layer deals with frame formation, flow control, error control, and addressing and link management. All such functions will be performed only by data link protocols. The sliding window protocol will detect and correct error if the received data have enough redundant bits or repeat a retransmission of data. The paper shows the working of this duplex protocol of data link network. Keywords: ACK, GOBACK, ARQ, NACK.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This presentation gives you the basic understanding about the simplex stop and wait protocol. It contains stop and wait ARQ and algorithms for stop and wait ARQ, and simplex stop and wait ARQ. Moreover it contains the case studies to make readers understand the protocol easily.
Abstract The data can get lost, reordered or duplicated due to the presence of routers and buffer space over the unreliable channel in the conventional networks. The data link layer deals with frame formation, flow control, error control, and addressing and link management. All such functions will be performed only by data link protocols. The sliding window protocol will detect and correct error if the received data have enough redundant bits or repeat a retransmission of data. The paper shows the working of this duplex protocol of data link network. Keywords: ACK, GOBACK, ARQ, NACK.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This presentation gives you the basic understanding about the simplex stop and wait protocol. It contains stop and wait ARQ and algorithms for stop and wait ARQ, and simplex stop and wait ARQ. Moreover it contains the case studies to make readers understand the protocol easily.
Short Presentation (2 Hrs) on SSL and TLS Protocol and its reference standard. Good for intermediate participant or technical who want to understand secure protocol an
Introduction to Secure Socket Layer (SSL) and Tunnel Layer Security (TLS). Shows basic principle of SSL and also little bit of practical applicability.
Data Link Control
FRAMING
The data link layer needs to pack bits into frames, so that each frame is distinguishable from another. Our postal system practices a type of framing. The simple act of inserting a letter into an envelope separates one piece of information from another; the envelope serves as the delimiter.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
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.
7. 11.7
In Selective Repeat ARQ, the sequence
numbers are modulo 2m
, however, the
size of the sender and receiver window
must be at most one-half of 2m
.
Note
14. 11.14
This example is similar to Example on Go-Back-N-ARQ
in which frame 1 is lost. We show how Selective Repeat
behaves in this case. Figure shows the situation. One
main difference is the number of timers. Here, each
frame sent or resent needs a timer, which means that the
timers need to be numbered (0, 1, 2, and 3). The timer for
frame 0 starts at the first request, but stops when the ACK
for this frame arrives. The timer for frame 1 starts at the
second request, restarts when a NAK arrives, and finally
stops when the last ACK arrives. The other two timers
start when the corresponding frames are sent and stop at
the last arrival event.
Example
15. 11.15
At the receiver site we need to distinguish between the
acceptance of a frame and its delivery to the network
layer. At the second arrival, frame 2 arrives and is stored
and marked, but it cannot be delivered because frame 1 is
missing. At the next arrival, frame 3 arrives and is
marked and stored, but still none of the frames can be
delivered. Only at the last arrival, when finally a copy of
frame 1 arrives, can frames 1, 2, and 3 be delivered to the
network layer. There are two conditions for the delivery
of frames to the network layer: First, a set of consecutive
frames must have arrived. Second, the set starts from the
beginning of the window.
Example (continued)
16. 11.16
Another important point is that a NAK is sent after the
second arrival, but not after the third, although both
situations look the same. The reason is that the protocol
does not want to crowd the network with unnecessary
NAKs and unnecessary resent frames. The second NAK
would still be NAK1 to inform the sender to resend frame
1 again; this has already been done. The first NAK sent is
remembered (using the nakSent variable) and is not sent
again until the frame slides. A NAK is sent once for each
window position and defines the first slot in the window.
Example (continued)
17. 11.17
The next point is about the ACKs. Notice that only two
ACKs are sent here. The first one acknowledges only the
first frame; the second one acknowledges three frames. In
Selective Repeat, ACKs are sent when data are delivered to
the network layer. If the data belonging to n frames are
delivered in one shot, only one ACK is sent for all of them.
Example (continued)
21. 11.21
HDLCHDLC
High-level Data Link Control (HDLC)High-level Data Link Control (HDLC) is ais a bit-orientedbit-oriented
protocol for communication over point-to-point andprotocol for communication over point-to-point and
multipoint links. It implements the ARQ mechanismsmultipoint links. It implements the ARQ mechanisms
we discussed.we discussed.
25. 11.25
There are three fundamental types of HDLC frames:
- Information frames, or I-frames, transport user data from the network
layer. In addition they can also include flow and error control information
piggybacked on data.
- Supervisory Frames, or S-frames, are used for flow and error control
whenever piggybacking is impossible or inappropriate, such as when a
station does not have data to send. S-frames do not have information fields.
- Unnumbered frames, or U-frames, are used for various miscellaneous
purposes, including system/link management. Some U-frames contain an
information field, depending on the type.
27. 11.27
Poll/Final is a single bit with two names. It is called Poll when set by the primary station to
obtain a response from a secondary station, and Final when set by the secondary station to
30. 11.30
Figure shows how U-frames can be used for connection
establishment and connection release. Node A asks for a
connection with a set asynchronous balanced mode
(SABM) frame; node B gives a positive response with an
unnumbered acknowledgment (UA) frame. After these
two exchanges, data can be transferred between the two
nodes (not shown in the figure). After data transfer, node
A sends a DISC (disconnect) frame to release the
connection; it is confirmed by node B responding with a
UA (unnumbered acknowledgment).
Example
32. 11.32
Figure shows an exchange using piggybacking. Node A
begins the exchange of information with an
I-frame numbered 0 followed by another I-frame
numbered 1. Node B piggybacks its acknowledgment of
both frames onto an I-frame of its own. Node B’s first
I-frame is also numbered 0 [N(S) field] and contains a 2
in its N(R) field, acknowledging the receipt of A’s frames
1 and 0 and indicating that it expects frame 2 to arrive
next. Node B transmits its second and third I-frames
(numbered 1 and 2) before accepting further frames from
node A.
Example
33. 11.33
Its N(R) information, therefore, has not changed: B
frames 1 and 2 indicate that node B is still expecting A’s
frame 2 to arrive next. Node A has sent all its data.
Therefore, it cannot piggyback an acknowledgment onto
an I-frame and sends an S-frame instead. The RR code
indicates that A is still ready to receive. The number 3 in
the N(R) field tells B that frames 0, 1, and 2 have all been
accepted and that A is now expecting frame number 3.
Example (continued)
35. 11.35
Figure shows an exchange in which a frame is lost. Node
B sends three data frames (0, 1, and 2), but frame 1 is
lost. When node A receives frame 2, it discards it and
sends a REJ frame for frame 1. Note that the protocol
being used is Go-Back-N with the special use of an REJ
frame as a NAK frame. The NAK frame does two things
here: It confirms the receipt of frame 0 and declares that
frame 1 and any following frames must be resent. Node
B, after receiving the REJ frame, resends frames 1 and 2.
Node A acknowledges the receipt by sending an RR frame
(ACK) with acknowledgment number 3.
Example
37. 11.37
POINT-TO-POINT PROTOCOLPOINT-TO-POINT PROTOCOL
Although HDLC is a general protocol that can be usedAlthough HDLC is a general protocol that can be used
for both point-to-point and multipoint configurations,for both point-to-point and multipoint configurations,
one of the most common protocols for point-to-pointone of the most common protocols for point-to-point
access is theaccess is the Point-to-Point Protocol (PPP).Point-to-Point Protocol (PPP). PPP is byPPP is by
far the most common protocol used, when individualfar the most common protocol used, when individual
users connect to the Internet.users connect to the Internet.
53. 11.53
Let us go through the phases followed by a network layer
packet as it is transmitted through a PPP connection.
Figure shows the steps. For simplicity, we assume
unidirectional movement of data from the user site to the
system site (such as sending an e-mail through an ISP).
The first two frames show link establishment. We have
chosen two options (not shown in the figure): using PAP
for authentication and suppressing the address control
fields. Frames 3 and 4 are for authentication. Frames 5
and 6 establish the network layer connection using IPCP.
Example
54. 11.54
The next several frames show that some IP packets are
encapsulated in the PPP frame. The system (receiver)
may have been running several network layer protocols,
but it knows that the incoming data must be delivered to
the IP protocol because the NCP protocol used before the
data transfer was IPCP.
After data transfer, the user then terminates the data link
connection, which is acknowledged by the system. Of
course the user or the system could have chosen to
terminate the network layer IPCP and keep the data link
layer running if it wanted to run another NCP protocol.
Example (continued)