# INTRODUCTION Random Early Detection (RED) is the first active queue management algorithm proposed for deployment in TCP/IP networks. The basic idea behind an active queue management algorithm is to convey congestion notification early to the TCP end points so that they can reduce their transmission rates before queue overflow and sustained packet loss occur. "It is now widely accepted that the RED controlled queue performs better than a drop-tail queue. It is an active queue management algorithm" [1]. "The tail drop algorithm, a router buffer as many packets as it can, and drops the packet when it cannot buffer. If buffers are constantly full, the network is congested" [2]. RED addresses these issues. It monitor the average queue size and drops packets based on statistical probabilities. If the buffer is almost empty, all incoming packets reaccepted. As the queue grows, the probabilities for dropping incoming packet are dropped too. RED is more fair than trail drop in the sense of it does not possess a bias against burst traffic that use only a small portion of the bandwidth. The more the more a host transmits, likely it is that packets are dropped. The most common technique of queue management is a trail drop. In this method packets are accepted as long as there is space in the buffer when it becomes full, incoming packets are dropped. This approach results in dropping large number of packets in the time congestion. This can result in lower throughput and TCP synchronization [3]. However TCP includes eleven variants (Tahoe, FullTcp, TCP/Asym, Reno, Reno/Asym, Newreno/Asym, Sack1, DelAck and Sack1/DelAck) as source and five (TCPSink, TCPSink/Asym, Sack1, DelAck and Sack1/DelAck) as destination, implementation in NS-2 [4,5]. The base TCP has become known as TCP Tahoe. TCP Reno attaches one novel mechanism called Fast Recovery to TCP Tahoe [4]. In addition, TCP Newreno employs the most recent retransmission mechanism of TCP Reno. [6]. The use of Sacks allows the receiver to stipulate several additional data packets that have been received out-of-order within one dupack, instead of only the last in order packet received [5]. TCP Vegas offers its own distinctive retransmission and congestion control strategies. TCP Fack is Reno TCP with forward acknowledgment [7]. Transmission Control Protocol (TCP) Variants Reno, NewReno, Vegas, Fack and Sack1 are implemented in NS-2. RED supervises the average queue size and drops packets based on statistical likelihoods [3]. # II. RANDOM EARLY DETECTION a) RED Parameter Setting Average queue size avg is formulated [1] as: Where, wq is the queue weight, q is current queue size. wq should have lower value for bustier traffic; more weight is given in this case for the historic A III. We that when threshold increase then variation course in received among various TCP variants and all arriving packets are received when average queue size exceeds max threshold or less than minimum threshold then packets are dropped which is shown in above all tables and corresponding figure. We found that Newreno TCP variants is the best because mean number of received packet is high mean number of dropped packet is low. # PERFORMANCE ANALYSIS OF RED MODEL a) Variation in Threshold Value ![Figure1 : Graph of received packet for various TCP variants with respect to threshold for simulation time 70s](image-2.png "Figure1:Figure4:") ![of TCP and UDP i. Comparison of Received Packet](image-3.png "") ![Figure5 : comparison graph of received packet between UDP and TCP for simulation time 280s ii. Comparison of Dropped PacketTable 6 : Comparison of received packet between UDP and TCP Times 70s 140s 210s 280s U](image-4.png "Figure5:Figure6:") 1Number received packet for various TCP variants with respect to threshold for simulation time 70s 2 3 42011October46TCP variants1520253035Reno8541185845711733Newreno721763752774741Vegas821777685686625Fack800721713644761Sack1864870749813786TCP variants1520253035Reno1452 1532 1333 1778 1398Newreno1458 1465 1501 1631 1538Vegas1345 1578 1350 1498 1538Fack1412 1754 1252 2379 1422Sack11501 1339 1595 1358 1179TCP variants 1520253035Reno2659 2635 2376 1946 2300Newreno2701 2546 2032 2169 2303Vegas2254 2255 2301 2432 2178Fack2802 2462 2897 2131 2376Sack12269 2416 2201 2554 2082TCP variants1520253035Reno31423403331233232902Newreno33833220320432652928Vegas26242749277825382799Fack35453088285626814298Sack138883216305132323409© 2011 Global Journals Inc. (US) Global Journal of Computer Science and Technology Volume XI Issue XVIII Version I 5and TCPTimes 70s 140s 210s 280sU15 675 1294 1996 258620 797 1222 1803 2694D25 758 1187 2127 263330 795 1484 2085 2794P35 749 1336 1963 2783T15 566 1352 2725 245720 665 1606 2374 3284C25 637 1438 2425 369430 548 1656 2247 2832P35 834 1614 2413 3438 A Comprehensive Analysis of Congestion Control Using Random Early Discard (RED) Queue © 2011 Global Journals Inc. (US) From the aforementioned comparison of the performance it is found that TCP is better than UDP because packet received is higher in it with respect to UDP. That is why packet loss is lower in TCP. In case of packet drop, it is clear those packet drop is higher in UDP than TCP and also occur more congestion in it. It is possible to control congestion in TCP using RED model. IV. CONCLUSION 8. * SFloyd VJacobson Random Early Detection gateways for congestion avoidance * IEEE/ACM Transactions on Networking 1 4 1993 * An experimental analysis of random early discard (RED) queue for congestion control MDIslam MDMorshed MDIslam Mejbahul Azam 2011 * RED: Discussions of setting parameters SFloyd 1997 * The network simulator-ns-2 The VINT Project, A Collaboration between researchers at UC Berkeley, LBL, USC/ISI, and Xerox PARC 27 NS The ns Manual * Evaluation of different TCP versions non-wireline environments TanjaLang 2002 The University of South Australia, Institute for Telecommunications Research * NS Simulator for beginners VenezuelaMerida Essi Sophia-Antipolis Lecture notes France 2003. 2003-2004 Univ. de Los Andes