Comparative Performance Evaluation of TCP with Identical and Cross-Variant Congestion Control

Author(s):  
Nahida Nigar

The Transmission Control Protocol (TCP), a key functional building block of the Internet, operates as a rate-adaptive end-to-end protocol at the Transport Layer of the network protocol stack. It regulates the prevailing load conditions within the network by getting the source node to adapt the packet transfer rate in accord with the processing capacity of the receiver. The regulation is enforced by means of dropping of packets on the part of the receiver. The TCP sender then reduces the packet injection rate so as to allow the network to recover from congestion. The focus of this paper is performance evaluation of certain notable TCP congestion avoidance algorithms, namely, Vegas, Reno and New Reno. Specifically, a number of performance measures have been analysed based on ns-2 simulation data where the scenarios involved TCP flows operating with identical and cross-variant congestion control mechanisms. Congestion window behaviour, packet loss, throughput, transmission delay and jitter are the performance criteria studied with the setup mentioned. In the flows with identical variants, Vegas outperforms other TCP variants. However, TCP Vegas has been observed to contribute to unfair appropriation of the resources in the cross-variant setting.

Author(s):  
Tanjia Chowdhury ◽  
Mohammad Jahangir Alam

In the Transport layer, there are two types of Internet Protocol are worked, namely- Transmission Control Protocol (TCP) and User datagram protocol (UDP). TCP provides connection oriented service and it can handle congestion control, flow control, and error detection whereas UDP does not provide any of service. TCP has several congestion control mechanisms such as TCP Reno, TCP Vegas, TCP New Reno, TCP Tahoe, etc. In this paper, we have focused on the behavior performance between TCP Reno and TCP Vegas, TCP New Reno over TCP Reno, when they share the same bottleneck link at the router. For instigating this situation, we used drop-tail and RED algorithm at the router and used NS-2 simulator for simulation. From the simulation results, we have observed that the performance of TCP Reno and TCP Vegas is different in two cases. In drop tail algorithm, TCP Reno achieves better Performance and throughput and act more an aggressive than Vegas. In Random Early Detection (RED) algorithm, both of congestion control mechanism provides better fair service when they coexist at the same link. TCP NewReno provides better performance than TCP Reno.


Author(s):  
Nelson Luís Saldanha da Fonseca ◽  
Neila Fernanda Michel

In response to a series of collapses due to congestion on the Internet in the mid-’80s, congestion control was added to the transmission control protocol (TCP) (Jacobson, 1988), thus allowing individual connections to control the amount of traffic they inject into the network. This control involves regulating the size of the congestion window (cwnd) to impose a limit on the size of the transmission window. In the most deployed TCP variant on the Internet, TCP Reno (Allman, Floyd, & Partridge, 2002), changes in congestion window size are driven by the loss of segments. Congestion window size is increased by 1/cwnd for each acknowledgement (ack) received, and reduced to half for the loss of a segment in a pattern known as additive increase multiplicative decrease (AIMD). Although this congestion control mechanism was derived at a time when the line speed was of the order of 56 kbs, it has performed remarkably well given that the speed, size, load, and connectivity of the Internet have increased by approximately six orders of magnitude in the past 15 years. However, the AIMD pattern of window growth seriously limits efficienct operation of TCP-Reno over high-capacity links, so that the transport layer is the network bottleneck. This text explains the major challenges involved in using TCP for high-speed networks and briefly describes some of the variations of TCP designed to overcome these challenges.


Author(s):  
Bhaskar Sardar ◽  
Debashis Saha

Transmission Control Protocol (TCP), the most popular transport layer communication protocol for the Internet, was originally designed for wired networks, where bit error rate (BER) is low and congestion is the primary cause of packet loss. Since mobile access networks are prone to substantial noncongestive losses due to high BER, host motion and handoff mechanisms, they often disturb the traffic control mechanisms in TCP. So the research literature abounds in various TCP enhancements to make it survive in the mobile Internet environment, where mobile devices face temporary and unannounced loss of network connectivity when they move. Mobility of devices causes varying, increased delays and packet losses. TCP incorrectly interprets these delays and losses as sign of network congestion and invokes unnecessary control mechanisms, causing degradation in the end-to-end good put rate. This chapter provides an in-depth survey of various TCP enhancements which aim to redress the above issues and hence are specifically targeted for the mobile Internet applications.


Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 294
Author(s):  
Geon-Hwan Kim ◽  
Yeong-Jun Song ◽  
Imtiaz Mahmud ◽  
You-Ze Cho

The main design goals of the multipath transmission control protocol (MPTCP) are to improve the throughput and share a common bottleneck link fairly with a single-path transmission control protocol (TCP). The existing MPTCP congestion control algorithms achieve the goal of fairness with single-path TCP flows in a shared bottleneck, but they cannot maximize the throughput in nonshared bottlenecks, where multiple subflows traverse different bottleneck links. This is because the MPTCP is designed not to exceed the throughput of a single-path TCP competing in the bottleneck. Therefore, we believe that MPTCP congestion control should have different congestion window control mechanisms, depending on the bottleneck type. In this paper, we propose an adaptive decrease window (ADW) balanced linked adaptation (BALIA) congestion control algorithm that adaptively adjusts the congestion window decrease in order to achieve better throughput in nonshared bottlenecks while maintaining fairness with the single-path TCP flows in shared bottlenecks. The ADW-BALIA algorithm detects shared and nonshared bottlenecks based on delay fluctuations and it uses different congestion window decrease methods for the two types of bottleneck. When the delay fluctuations of the MPTCP subflows are similar, the ADW-BALIA algorithm behaves the same as the existing BALIA congestion control algorithm. If the delay fluctuations are dissimilar, then the ADW-BALIA algorithm adaptively modulates the congestion window reduction. We implement the ADW-BALIA algorithm in the Linux kernel and perform an emulation experiment that is based on various topologies. ADW-BALIA improves the aggregate MPTCP throughput by 20% in the nonshared bottleneck scenario, while maintaining fairness with the single-path TCP in the shared bottleneck scenario. Even in a triple bottleneck topology, where both types of bottlenecks exist together, the throughput increases significantly. We confirmed that the ADW-BALIA algorithm works stably for different delay paths, in competition with CUBIC flows, and with lossy links.


2010 ◽  
Vol 32 (6) ◽  
pp. 881-894 ◽  
Author(s):  
Frode Stenseng ◽  
Lina Harvold Dalskau

Two studies were conducted to investigate the paradoxical behavior of obsessively passionate individuals: they tend to continue involvement in their passion activity despite reporting the activity as a source of ill-being. We suggested that elevated self-esteem in activity engagement could be one such persistence-promoting factor. In Study 1, we found that obsessively passionate individuals reported lower levels of global self-esteem compared with harmoniously passionate individuals, whereas they reported similar levels of activity-related self-esteem. We suggest that this indicates that obsessively passionate individuals try to compensate for low global self-esteem by utilizing self-esteem contingencies in their passion activity. Study 2 showed that activity-related self-esteem among obsessively passionate individuals was found to be strongly related to comparative performance evaluations, whereas no such relationship was found among harmoniously passionate individuals. We suggest that self-esteem contingencies related to comparative performance criteria represent a persistence-promoting factor among obsessively passionate individuals.


2022 ◽  
Vol 2161 (1) ◽  
pp. 012018
Author(s):  
M Deeksha ◽  
Ashish Patil ◽  
Muralidhar Kulkarni ◽  
N. Shekar V. Shet ◽  
P. Muthuchidambaranathan

Abstract Vehicular ad hoc networks (VANETs) have emerged in time to reduce on-road fatalities and provide efficient information exchange for entertainment-related applications to users in a well-organized manner. VANETs are the most instrumental elements in the Internet of Things (IoT). The objective lies in connecting every vehicle to every other vehicle to improve the user’s quality of life. This aim of continuous connectivity and information exchange leads to the generation of more information in the medium, which could congest the medium to a larger extent. Decentralized congestion control (DCC) techniques are specified to reduce medium congestion and provide various safety applications. This article presents two DCC mechanisms that adapt message rate and data rate combined with transmit power control mechanism. These mechanisms are developed under multi-state active design proposed by the standard. The proposed methods deliver better performance over other mechanisms in terms of power, channel load, and channel utilization using real-time-based scenarios by simulation in SUMO.


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