V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....links characterized by a high bit error rate. Several schemes have been proposed to decouple the congestion control of TCP from its error control. They aim to let TCP retransmit the errors without reducing considerably the throughput. TCP uses two algorithms, slow start and congestion avoidance [4], to adapt its window to the network state. We assume that W is measured in segments not in bytes. Starting at W = 1, slow start is used to increase W by one segment for every incoming ACK until we reach a threshold W th considered as an estimation of the network capacity. This exponential growth ....

V. Jacobson, iCongestion avoidance and controlj, Proc. ACM Sigcomm'88, Stanford, CA, USA, Aug. 1988.

....sequence number (the original plus three Duplicate ACKs) indicates the loss of the packet following the last packet acknowledged. The number four is chosen to minimize the probability that a reordering of packets causes a wrong error detection. Congestion control has been added to TCP by Jacobson [26]. An additive increase multiplicative decrease strategy has been adopted to change the window size, and therefore the throughput, as a function of network conditions. The window used for AEow control is always taken as the minimum of the congestion window and the one advertised by the receiver. ....

....network for any extra bandwidth. The probe continues until a loss occurs. Here, the source supposes that the network is getting into congestion and it sets its estimation of the capacity to half the current size of the window. The rst version of TCP that implements congestion control, called Tahoe [26], sets the congestion window 2 A segment is the size of data in a TCP packet. RR n# 0123456789 6 Barakat, Altman, and Dabbous at this point to one and uses again slow start to reach the new estimation of the capacity. Slow starting after every loss deteriorates the performance given the low ....

V. Jacobson, iCongestion avoidance and controlj, in ACM SIGCOMM, Stanford, CA, USA, August 1988.

....beyond the maximum input rate, the more important congestion losses become. The evolution of the input rate is more and more controlled by the available bandwidth in the network and the buoeer sizes rather than by random losses. This is the assumption a congestion control protocol as TCP IP [9] makes about the network. The best performance is obtained when random losses are suOEciently rare. The condition for random losses to be negligible is that the average input rate during the bad state of the channel given by our model (i.e. when ignoring congestion losses) is much larger than the ....

V. Jacobson, iCongestion avoidance and controlj, in Proc. ACM Sigcomm'88, Stanford, CA, USA, August 1988.

....transmis pendant la phase slow start. Mots cl#s : TCP, Slow Start, Congestion Avoidance, Liens Satellites, Mod#lisations, Simulations, #valuation de Performance. Improving TCP over Satellite Links 3 1 Introduction TCP, the window based reliable Transmission Control Protocol of the Internet [11, 18], uses two algorithms Slow Start and Congestion Avoidance to control the AEow of packets in a network. With slow start, the window of the sender is set initially to one segment and it is increased by one for every acknowledgment (ACK) received. The result is an exponential growth of the connection ....

....this linear growth, which is slower than the exponential one during slow start, continues until we reach the maximum reachable window Wmax . This is the maximum number of TCP packets that can be t into the pipe and the buoeer. Here, a loss occurs due to buoeer overAEow. According to TCP tahoe [11] used in this paper, W th is set to half Wmax and W to 1. A new slow start and then a new TCP cycle begins. We give Wmax the value found in [7] Wmax = B Gamma ( Gamma ) 1 (3) We note here that the addition of the exogenous traOEc reduces the share of the TCP connection in the buoeer and ....

V. Jacobson, iCongestion avoidance and controlj, Proc. ACM Sigcomm'88, Stanford, CA, USA, Aug. 1988.

....to Sr. Because all the nodes between N and D receive packets at a rate slower than their available bandwidth, their parameters don t aoeect the performance of TCP. The following analysis focuses on the impact on TCP of nodes between Sr and N . According to TCP congestion control algorithms [5, 9], if ACKs are not lost nor delayed, an ACK triggers maximum the transmission of a burst of two packets. This happens upon every ACK reception during SS and when the congestion window W increases by one segment during CA. If the nodes between Sr and N have an available bandwidth 2, the ....

....to other values of W th . A condition to not encounter the problem of losses during SS has been calculated in [1, 7] This condition accounts only for the main bottleneck. In this section, we recalculate this condition with our general model. As in these works, we consider a Tahoe version of TCP [5, 4] where SS is frequently called. We divide a SS phase into mini cycles of duration T [7] W doubles every T . During mini cycle n, Sr sends a burst of 2 n packets at rate 2. Mini cycle n 1 starts when the ACK for the rst packet of this burst reaches Sr. These bursts propagate from node to node ....

V. Jacobson, iCongestion avoidance and controlj, ACM Sigcomm, Aug. 1988.

....of our general model and then we identify their parameters from real TCP traces. 1 Introduction We study in this paper the performance of an additive increase multiplicativedecrease AEow control protocol. This is the kind of control used by TCP, the widelyused transport protocol of the Internet [9]. TCP is used as a reference through the present work, however we anticipate that our results will be also applicable for other AEow control mechanisms. A AEuid approach is used to model the controlled AEow. The transmission rate of the source is assumed to grow linearly at a rate ff. In the case ....

V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

....in this paper the tradeooe between the bandwidth consumed by FEC and that gained by TCP. 1 Introduction Forward Error Correction (FEC) is widely used to improve the quality of noisy transmission media as wireless links [2, 4] This improvement is of importance for a transport protocol as TCP [8, 16] which uses the loss of packets as an indication of network congestion. A TCP packet corrupted while crossing a noisy link is discarded before reaching the receiver which results in an unnecessary window reduction at the TCP source, and hence in a deterioration of the performance of the TCP ....

V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug. 1988.

....to adapt to the varying network conditions often use decentralized control protocols in order to optimize their own performances. This is, for example, the case when transmitting data over the Internet, where users themselves determine their transmission rates (typically using the TCP IP protocol [16]) The need for decentralized distributed individual controls in telecommunication networks has stimulated a substantial amount of research using game theoretic methods, in both routing and AEow control [2, 3, 6, 7, 8, 9, 11, 12, 15, 17, 18, 20, 19, 22, 23, 24, 26] Within the design of AEow ....

V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM `88, Stanford, CA, 314329, August 1988.

....and characterize the parameters of a connection. Much of the work described in the literature has focused on analyzing and estimating characteristics of connections such as end to end capacity, delay, and loss. The results have been used to design of routing and AEow control algorithms (e.g. [14, 16, 5]) to dimension buoeers and link capacity (e.g. 21, 9] and to choose parameters in simulation and analytic studies (e.g. 7, 29] They have also proved very important in the design of proper mechanisms for real time applications. For example, estimating shape of the delay distribution is ....

....by including a dependence on packet length in the retransmission timeout algorithm. Several other studies have since addressed timeout adjustment in TCP, and they have proposed improvements to take into account packet losses, packet retransmissions, and the variance of packet round trip delays [14]. More recent studies have considered the delay and loss behavior in the NSFNET, and more generally in the Internet. It is convenient to classify these studies depending on the dioeerent time scales over which the above behavior has been observed. Coarse grained NSFNET statistics obtained from ....

V. Jacobson, iCongestion avoidance and controlj, Proc. ACM Sigcomm `88, Stanford, CA, pp. 314-329, August 1988.

....is conducted over the real Internet and a comparison is provided with other models which make simple assumptions on the inter loss time process. 1. INTRODUCTION We analyze in this paper the performance of TCP (Transmission Control Protocol) the widely used transport protocol of the Internet [15, 30]. TCP is a reliable window based AEow control protocol where the window is increased until a packet loss is detected. Here, the source assumes that the network is congested and reduces its window. Once the lost packets are recovered, the source resumes its window increase. As a performance ....

V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

....show that the time average of the transmission rate increases with the burstiness of losses. We nally examine the impact of burstiness of losses on the transmission rate variability. 1. INTRODUCTION Flow control mechanisms in the Internet, particularly those of the Transmission Control Protocol [12], use the loss of packets as an indication of network congestion. In general, the transmission rate of the controlled AEow is linearly increased until a loss occurs. The network is supposed here to be congested and the transmission rate is multiplicatively decreased in order to alleviate this ....

....The transmission rate is halved and the linear growth is then resumed. This model approximates the performance of several versions of TCP IP where the transmission rate at any instant is equal to the window size divided by the RTT and where the window increases linearly by 1 packet every RTT [12]. If the delay ACKs mechanism is implemented at the destination, the increase in TCP window is by one packet every two RTTs. This linear window increase corresponds to the congestion avoidance mode of TCP. The slow start mode is neglected in this paper due its fast exponential window increase. The ....

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

....in the heterogeneity of the Internet. High speed links (Fiber optic) long and variable delay paths (Satellite links) lossy links (Wireless networks) asymmetric paths (Hybrid satellite networks) and others, are becoming widely embedded in the Internet. Many works have studied by experimentations [5, 6, 10, 12], analytical modeling [3, 8, 13, 14] and simulations [7, 8, 9, 11] the performance of TCP in this new environment. Most of these works have focused on a particular environment: satellite networks, mobile networks, etc. They have shown some problems in the operation of TCP. Long propagation delay ....

....we present the proposed solutions as well as our comments in four corresponding sections. 2 Overview of TCP TCP is a reliable window based ACK clocked AEow control protocol. It uses an additive increase multiplicative decrease strategy for changing its window as a function of network conditions [1, 12]. Starting from one packet, or a larger value as we will see later, the window is increased exponentially by one packet for every non duplicate ACK until the source estimate of the network capacity is reached. By capacity of the network, sometimes called the pipe size, we mean the maximum number ....

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug. 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM Sigcomm, Aug 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Stanford, CA, 314-329, Aug. 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM, Aug 1988.

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V. Jacobson, iCongestion avoidance and controlj, Proc. ACM Sigcomm '88, Stanford, CA, Aug. 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM `88, Stanford, CA, 314-329, August 1988.

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V. Jacobson, iCongestion avoidance and controlj, ACM SIGCOMM `88, Stanford, CA, 314-329, August 1988.

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V. Jacobson, iCongestion avoidance and controlj, Proc. ACM Sigcomm'88, Stanford, CA, USA, Aug. 1988.

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V. Jacobson, iCongestion avoidance and controlj, in Proc. ACM Sigcomm'88, Stanford, CA, USA, Aug. 1988.

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