Suppose two TCP connections share a path through a router R. The router's queue size is six segments; each connection has a stable congestion window of three segments. No congestion control is used by these connections. A third TCP connection now is attempted, also through R. The third connection does not use congestion control either. Describe a scenario in which, for at least a while, the third connection gets none of the available bandwidth, and the first two connections proceed with 50% each. Does it matter if the third connection uses slow start? How does full congestion avoidance on the part of the first two connections help solve this?

Suppose two TCP connections share a path through a router R. The router's queue size is six segments; each connection has a stable congestion window of three segments. No congestion control is used by these connections. A third TCP connection now is attempted, also through R. The third connection does not use congestion control either. Describe a scenario in which, for at least a while, the third connection gets none of the available bandwidth, and the first two connections proceed with 50% each. Does it matter if the third connection uses slow start? How does full congestion avoidance on the part of the first two connections help solve this?

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Suppose two TCP connections share a path through a router R. The router's queue size is six segments; each connection has a stable congestion window of three segments. No congestion control is used by these connections. A third TCP connection now is attempted, also through R. The third connection does not use congestion control either. Describe a scenario in which, for at least a while, the third connection gets none of the available bandwidth. and the first two connections proceed with 50% each. Does it matter if the third connection uses slow start? How does full congestion avoidance on the part of the first two connections help solve this? 10:33 am Type a message Dorcon 1 tahir re
Suppose a client is communication with a server via a TCP Reno connection. The client has sent the data up to sequence number 120. The client has received acknowledgment number 80 from the server, and the received window is 50 in the last message received by the client from the server. Moreover, the client has estimated the congestion window as 36 for the server. If the client receives two more acknowledgment number 80, then how much maximum data the client can send to the server? Justify your answer via proper references and procedure. (coding required)
In TCP connection, congestion occurs if the load on the network is greater than the capacity of the network. TCP uses the following algorithm to handle congestion. The algorithm is based on the size of the congestion window (cwnd) which starts with one maximum segment size (MSS). The MSS is determined during connection establishment. At each time the whole window of segments is acknowledged (one transmission), the size of the window grows exponentially. To stop this exponential growth, the sender keeps the track of a threshold. The threshold is set to 16 MSS. After reaching the threshold, the size of the congestion window is increased by 1. After how many transmissions the congestion window size will be 22 MSS?
Consider one TCP connection on a path with a bottleneck link with capacity L. We have a file of size F(assume F is a very large file size). If TCP segment size is B bytes, the two-way propagation delay is tp and connection is always in congestion avoidance phase, find the following: A. Maximum window size that TCP can achieve B. Average window size and average throughput in this TCP connection C. Time it will take from connection establishment to reaching the maximum window size.
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Phases of TCP congestion control. Consider the figure below, which plots the evolution of TCP's congestion window at the beginning of each time unit (where the unit of time is equal to the RTT); see Figure 3.53 in the text. In the abstract model for this problem, TCP sends a "flight" of packets of size cwnd at the beginning of each time unit. The result of sending that flight of packets is that either (i) all packets are ACKed at the end of the time unit, (ii) there is a timeout for the first packet, or (iii) there is a triple duplicate ACK for the first packet. Congestion window size (in segments) 40 35 30 25 20 15 10 5 0 www 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time unit (in RTT) A. During which of the following intervals of time is TCP performing slow start*? B. During which of the following intervals of time is TCP performing congestion avoidance*? C. At the end of which units of time does TCP detect a triple-duplicate-ACK*?…
Suppose a TCP connection, with window size 1, loses every other packet. Those that do arrive have RTT: 1 second. What = happens? What happens to TimeOut? Do this for two cases: (a) After a packet is eventually received, we pick up where we left off, resuming with Estimated RTT initialized to its pre-timeout value, and TimeOut double that. (b) After a packet is eventually received, we resume with TimeOut initialized to the last exponentially backed-off value used for the timeout interval. In the following four exercises, the calculations involved are straightforward with a spreadsheet.
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Consider a client connecting to a web server via a router as shown in Fig.Q2. Client A sends a request to the server to retrieve a 7.5 Mbytes file. Given that the segment size is 50 Kbytes, the round trip time (RTT) between the server and client is 10 ms, the initial slow-start threshold is 16 and the client's buffer always has a storage space of 1 Mbytes. Assume that TCP Reno is used, there is no loss during transmission and the headers of protocols are ignored. 400 Mbps 200 Mbps 400 Mbps Link a Link b Link c Client Web Server Fig.Q2 (a) Describe how the value of sending window changes as a function of time (in units of RTT) during the whole connection time. 2.
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