A Review of Router based Congestion Control Algorithms <s> C. Performance parameters Analysis <s> The authors present random early detection (RED) gateways for congestion avoidance in packet-switched networks. The gateway detects incipient congestion by computing the average queue size. The gateway could notify connections of congestion either by dropping packets arriving at the gateway or by setting a bit in packet headers. When the average queue size exceeds a present threshold, the gateway drops or marks each arriving packet with a certain probability, where the exact probability is a function of the average queue size. RED gateways keep the average queue size low while allowing occasional bursts of packets in the queue. During congestion, the probability that the gateway notifies a particular connection to reduce its window is roughly proportional to that connection's share of the bandwidth through the gateway. RED gateways are designed to accompany a transport-layer congestion control protocol such as TCP. The RED gateway has no bias against bursty traffic and avoids the global synchronization of many connections decreasing their window at the same time. Simulations of a TCP/IP network are used to illustrate the performance of RED gateways. > <s> BIB001 </s> A Review of Router based Congestion Control Algorithms <s> C. Performance parameters Analysis <s> Virtual Queue-based marking schemes have been recently proposed for AQM (Active Queue Management) in Internet routers. We consider a particular scheme, which we call the Adaptive Virtual Queue (AVQ), and study its following properties: stability in the presence of feedback delays, its ability to maintain small queue lengths and its robustness in the presence of extremely short flows (the so-called web mice). Using a mathematical tool motivated by the earlier work of Hollot et al, we present a simple rule to design the parameters of the AVQ algorithm. We then compare its performance through simulation with several well-known AQM schemes such as RED, REM, PI controller and a non-adaptive virtual queue algorithm. With a view towards implementation, we show that AVQ can be implemented as a simple token bucket using only a few lines of code. <s> BIB002 </s> A Review of Router based Congestion Control Algorithms <s> C. Performance parameters Analysis <s> This paper describes and evaluates stochastic fair blue (SFB), a novel technique for enforcing fairness among a large number of rows. SFB scalably detects and rate-limits non-responsive flows through the use of a marking probability derived from the blue queue management algorithm and a Bloom (1970) filter. Using analysis and simulation, SFB is shown to effectively handle non-responsive flows using an extremely small amount of state information. <s> BIB003 </s> A Review of Router based Congestion Control Algorithms <s> C. Performance parameters Analysis <s> This paper proposes a rate-based active queue management algorithm or RAQM. It uses the aggregated traffic input rate to calculate packet drop probability according to an exponential rule. The proposed RAQM algorithm works in two modes: queue-independent and queue-dependent. In the queue-independent mode, it only relies on the aggregate traffic input rate to regulate the input rate to the expected value, i.e. expected link utility. In the queue-dependent mode, it also uses the instantaneous queue length to further adjust the packet drop probability and to regulate the queue length to the expected value. We analyze the stability and investigate practical implementation issues of the RAQM. Simulations are carried out to study RAQM performance and to compare with other AQM algorithms, in particular PI and REM schemes. The results demonstrate that RAQM achieves better stability and faster response as it can quickly regulate the queue length to the expected value with small overshoot. RAQM also obtains better tradeoff between link utilization and queuing delay, and obtains higher goodput with the same buffer size as in PI and REM schemes. Finally RAQM has O(1) complexity, thus independent of the number of flows. <s> BIB004 </s> A Review of Router based Congestion Control Algorithms <s> C. Performance parameters Analysis <s> A new rate-based active queue management (AQM) algorithm, called Yellow, is proposed in the paper. Yellow uses the load factor (link utilization) as a main merit to manage congestion. To improve congestion control performance, a queue control function (QCF) is introduced as a secondary merit. The sufficient condition for globally asymptotic stability is presented based on Lyapunov theory. Furthermore, the principle for parameter settings is given based on the bounded stable conditions. We then illustrate that Yellow outperforms the recently proposed AQM algorithms in terms of link utilization, packet loss and robust performance through extensive simulations. <s> BIB005 </s> A Review of Router based Congestion Control Algorithms <s> C. Performance parameters Analysis <s> Active queue management (AQM) is an effective means to enhance congestion control, and to achieve trade-off between link utilization and delay. The de facto standard, random early detection (RED), and many of its variants employ queue length as a congestion indicator to trigger packet dropping. Despite their simplicity, these approaches often suffer from unstable behaviors in a dynamic network. Adaptive parameter settings, though might solve the problem, remain difficult in such a complex system. Recent proposals based on analytical TCP control and AQM models suggest the use of both queue length and traffic input rate as congestion indicators, which effectively enhances stability. Their response time generally increases however, leading to frequent buffer overflow and emptiness. In this paper, we propose a novel AQM algorithm that achieves fast response time and yet good robustness. The algorithm, called Loss Ratio-based RED (LRED), measures the latest packet loss ratio, and uses it as a complement to queue length for adaptively adjusting the packet drop probability. We develop an analytical model for LRED, which demonstrates that LRED is responsive even if the number of TCP flows and their persisting times vary significantly. It also provides a general guideline for the parameter settings in LRED. The performance of LRED is further examined under various simulated network environments, and compared to existing AQM algorithms. Our simulation results show that, with comparable complexities, LRED achieves shorter response time and higher robustness. More importantly, it trades off the goodput with queue length better than existing algorithms, enabling flexible system configurations <s> BIB006 </s> A Review of Router based Congestion Control Algorithms <s> C. Performance parameters Analysis <s> Active Queue Management (AQM) is an effective mechanism to improve the performance of end-to-end congestion control. However, existing AQM schemes are sensitive to network traffic changes. In this paper, we propose a novel AQM algorithm based, for the first time, on the optimized second-order system model, called Adaptive Optimized Proportional Controller (AOPC). AOPC measures the latest packet loss ratio, and uses it as a complement to queue length in order to dynamically adjust packet drop probability. Through using TCP throughput model, AOPC is capable of detaching from the number of TCP sessions N and insensitive to various network conditions. The parameter tuning rule is in compliance with the optimized second-order system model which has a small overshoot and fast convergence speed. We comprehensively evaluate the performances of AOPC through extensive simulations using NS2 simulator, and contrast it with previous approaches such as REM, PI, PID, PIP, and LRED. Simulation results demonstrate that AOPC is more responsive to time-varying network conditions than other algorithms, and obtains the best tradeoff between utilization and delay. <s> BIB007 </s> A Review of Router based Congestion Control Algorithms <s> C. Performance parameters Analysis <s> Two major goals of queue management are flow fairness and queue-length stability However, most prior works dealt with these goals independently. In this paper, we show that both goals can be effectively achieved at the same time. We propose a novel scheme that realizes flow fairness and queue-length stability. In the proposed scheme, high-bandwidth flows are identified via a multilevel caching technique. Then, we calculate the base drop probability for resolving congestion with a stable queue, and apply it to individual flows differently depending on their sending rates. Via extensive simulations, we show that the proposed scheme effectively realizes flow fairness between unresponsive and TCP flows, and among heterogeneous TCP flows, while maintaining a stable queue. <s> BIB008
Performance parameters considered for router based congestion control techniques are listed in the Table 1 . It can be observed Table-1 that the three performance parameterspacket loss rate, queue length and queuing delay have considered most important parameters while designing end to end based congestion control algorithms. Queuing delay and packet loss rate are the performance metrics which affects the QoS of multimedia traffic. There is a direct relationship between the queue length and packet loss rate as larger the average queue size higher the packet loss rate. Loss rate is defined as the number of dropped packets divided by the total number of packets arrived at the router's input ports. Router output queue length variation is examined over time, in order to measure the average queuing delay and its standard deviation. Minimizing average queuing delay is an important goal for real-time applications. On the other hand, the standard deviation gives a measure of the jitter at the destination hosts which is considered as an important metric for audio/video play back applications. The metric goodput reflects the best use of the available router resources and can be defined as the bandwidth delivered to all the receivers, excluding duplicate packets.Fairness against nonresponsive flows plays an important role while evaluating a AQM approach. Since an AQM mechanism is a sort of congestion control mechanisms, it needs to have robustness over network failures. Namely, even if a network failure occurs, it is desirable for an AQM mechanism to continue its operation. Generally, it is also desirable for congestion control of an AQM mechanism to be decentralized and distributed. Since, for example, other network devices may break down, control information that an AQM mechanism uses may not arrive on time. Even in such a case, the AQM mechanism should operate without serious trouble. Queue stability is a desirable feature of an AQM policy since it helps in minimizing the packet loss rate.From the viewpoint of Internet serviceproviders, maintaining queue-length stability is also important for maximizing link utilization with reduced buffer requirements BIB008 .Maintaining stable queue length at a link is critical for improving service quality as well as increasing utilization and decreasing buffer cost. With a stable queue, a flow may exhibit a stable delay with a low jitter as well as a stable loss rate. Implementation complexity plays an important role while deployment of AQM method in actual network environment. Following tradeoffs are observed in parameters of router based congestion control algorithms. References goodput and queuing delay BIB004 , BIB001 link utilization and queue length BIB002 link utilization and queuing delay BIB003 , BIB005 , BIB007 goodput and queue length BIB006 Copyright This work explores the literature review of router based congestion control algorithms in the context of wired networks. We understand that the identified issues and challenges regarding the router based congestion control algorithms may help in future research in this area. This initial proposition of such a review may be purposefully used by the academician/researchers and the corresponding useful feedback may be analyzed.