Sliding window protocol in computer networks

This article includes a list of general it lacks sufficient corresponding Please help to ( August 2010) ( A sliding window protocol is a feature of packet-based Packet-based systems are based on the idea of sending a batch of data, the packet, along with additional data that allows the receiver to ensure it was received correctly, perhaps a The time that it takes for the ACK signal to be received may represent a significant amount of time compared to the time needed to send the packet. In this case, the overall window, to be sent without having to wait for an ACK. Each packet receives a sequence number, and the ACKs send back that number. The protocol keeps track of which packets have been ACKed, and when they are received, sends more packets. In this way, the window slides along the stream of packets making up the transfer. Sliding windows are a key part of many protocols. It is a key part of the TCP protocol, which inherently allows packets to arrive out of order, and is also found in many Basic concept [ ] Conceptually, each portion of the transmission (packets in most data link layers, but bytes in TCP) is assigned a unique consecutive sequence number, and the receiver uses the numbers to place received packets in the correct order, discarding duplicate packets and identifying missing ones. The problem with this is that there is no limit on the size of the sequence number that can be required. By placing limits on the number of packets that can be transmitted or receiv...

Overview The sliding window protocol is a data link layer protocol that is useful in the sequential and reliable delivery of the data frames. Using the sliding window protocol, the sender can send multiple frames at a time. The sliding window protocol uses a mechanism of sequence numbers. The sender associates a sequence number to the data frames so that the receiver can use this sequence number to arrange the frames in order if any frame was re-transmitted. The sequence number also helps the receiver identify the loss of damaged packets. When the receiver receives the frame, it sends back an ACK (acknowledgment) to the sender. The ACK lets the sender know that a particular frame is received by the receiver correctly. There are two types of sliding window protocols namely - Go-Back-N ARQ, and Selective Repeat ARQ. Scope The article covers topics such as • Introduction to Sliding Window Protocol. • What are the types of sliding window protocol? • The working of the sliding window protocol. Each of the topics is explained clearly with diagrams and examples wherever necessary. What is Sliding Window Protocol? Before learning about the sliding window protocol, let us first learn about computer networks, the OSI model, and the data link layer (as the Sliding Window Protocol is related to the data link layer). A computer network is a set of devices (computers) connected to exchange information and resources such as files etc. The OSI model stands for Open Systems Interconnection...

This is a task in a lecture on computer networks: "Suppose you are designing a sliding window protocol for a 1-Mbps point-to-point link to the moon, which has a one-way latency of 1.25 seconds. Assuming that each frame carries 1 KB of data, what is the minimum number of bits you need for the sequence number?" R = 1-Mbps = 125KBps d_prop = 1.25 sec so I assume RTT = 2.5 sec The solution I was given ignores the transmission delay but I calculated it to be d_trans = 1KB/125KBps = 0.008s Within one second you can put 125 frames into the link if you allow full utilization. I assume the task ignores the size of the acknowledgements as well as the processing and transmission delay of the receiver for simplicity. Nothing else is said about the links properties. Since within 1 second you could send 125 frames, within 2.5 seconds you could send. 312.5 frames. If we include the senders d_trans then within 2.508 seconds we could send frames 313.5 frames until the acknowledgement for the first frame should be received. If you complete the LastFrameSent then I think you should need a send_window_size(SWS) of 314 to acknowledge each frame individually. In this case you would need Ceil(log2(314)) = 9 bits for the sequence numbers. The solution given by the tutor says that you need at least 10 bits and part of the explanation I noted down is that (ignoring d_trans) you can send 312 frames until the first frame is received. And then you can supposedly send another 312 frames until you recei...

\( \newcommand\) • • • Stop-and-wait is reliable but it is not very efficient (unless the path involves neither intermediate switches nor significant propagation delay; that is, the path involves a single LAN link). Most links along a multi-hop stop-and-wait path will be idle most of the time. During a file transfer, ideally we would like zero idleness (at least along the slowest link; see 6.3 Linear Bottlenecks). We can improve overall throughput by allowing the sender to continue to transmit, sending Data[N+1] (and beyond) without waiting for ACK[N]. We cannot, however, allow the sender get too far ahead of the returning ACKs. Packets sent too fast, as we shall see, simply end up waiting in queues, or, worse, dropped from queues. If the links of the network have sufficient bandwidth, packets may also be dropped at the receiving end. Now that, say, Data[3] and Data[4] may be simultaneously in transit, we have to revisit what ACK[4] means: does it mean that the receiver has received only Data[4], or does it mean both Data[3] and Data[4] have arrived? We will assume the latter, that is, ACKs are cumulative: ACK[N] cannot be sent until Data[K] has arrived for all K≤N. With this understanding, if ACK[3] is lost then a later-arriving ACK[4] makes up for it; without it, if ACK[3] is lost the only recovery is to retransmit Data[3]. The sender picks a window size, winsize. The basic idea of sliding windows is that the sender is allowed to send this many packets before waiting for...

What is the sliding window protocol for flow control in Computer Network? The computer networks use a sliding window protocol for optimal usage of the underlying network bandwidth. It allows a sender to send more than one packet at a single time. If there is no need for reliable delivery, the sliding window protocol is an optional implementation in the protocol layers. The sliding window protocol belongs to the category of flow control mechanism in computer networks. Why do we need flow control? How does reliable communication work? For reliable communication, the first basic thing is that the sender should make sure that the sent packet has been received by the receiver. For that, there is an acknowledgment for each data unit sent. The simple approach for reliable communication is that the sender sends a single packet at a time and waits for the acknowledgment. Upon receiving acknowledgment, the sender sends the next packet else, assuming the packet has been lost or corrupted. For error recovery same packet is retransmitted and again waits for an acknowledgment. The problem with this basic approach is that at a time there will be a single packet over the network even though there is more bandwidth available. The basic approach for a reliable delivery reduces the usage of underlying bandwidth and slower communication between the sender and receiver. What is a window in a computer network? And sliding means? To overcome the issue discussed above, the sender and receiver hav...

By • What is sliding window (windowing)? The sliding window (windowing) technique is used by Transmission Control Protocol ( The data link layer in the sliding window protocols. Sliding window protocols ensure the reliable and sequential delivery of data Figure 1. Data link layer of OSI's network model supports a class of protocols that use the sliding window technique. How does the sliding window technique work? A sliding window protocol controls and optimizes packet flow between a sender and receiver, while ensuring a balanced approach to packet delivery. The protocol requires the receiver to acknowledge receipt of each The receiver maintains a buffer to manage the flow of data packets. The receive buffer holds the packets that have been sent by the sender but have not yet been processed. During data transmission, the receiver notifies the sender of the amount of free space available in the receive buffer. This space is referred to as the receive window, which is the buffer size less the amount of unprocessed data. The sender cannot send more data packets than the amount of space available in the receive window. Data packets are numbered sequentially so they can be tracked when data is being transmitted from the sender to the receiver. During the transmission process, the data packets pass through one of four stages: • Sent and acknowledged by the receiver. • Sent but not acknowledged by the receiver. • Not sent but the receiver is ready accept them. • Not sent and the r...

Overview Go Back N ARQ which stands for Go Back N Automatic Repeat Request (ARQ) is a data link layer protocol that is used for data flow control purposes. It is a sliding window protocol in which multiple frames are sent from sender to receiver at once. The number of frames that are sent at one depends upon the size of the window that is taken. Scope of the Article • This article defines what the Go Back N ARQ protocol is along with its important features. • The working of the Go Back N ARQ protocol will also be discussed in detail. • Advantages and disadvantages of the Go Back N ARQ protocol will be discussed in the article. What is Go-Back-N ARQ? We all know that the Data Link Layer (DLL) in the OSI model is responsible for the flow and error control of the data which is sent from sender to receiver. This flow and error control mechanism follows some set of rules/protocols. We will be discussing flow control protocols in this article. The flow control protocols are generally divided into two categories i.e. • Stop and wait protocol • Sliding window protocol. The difference between these two categories of flow control protocols is that in the stop and wait protocol, only one data frame is sent at a time from sender to receiver. While in sliding window protocol, multiple frames can be sent at a time from sender to receiver. Go Back N ARQ is a sliding window protocol which is used for flow control purposes. Multiple frames present in a single window are sent together from ...