The project focuses on how Congestion Control and Queue Management techniques have evolved in the course of time and being modified to minimize packet loss and stabilize Queue length
IMPACT OF CONTENTION WINDOW ON CONGESTION CONTROL ALGORITHMS FOR WIRELESS ADH...cscpconf
TCP congestion control mechanism is highly dependent on MAC layer Backoff algorithms that
predict the optimal Contention Window size to increase the TCP performance in wireless adhoc
network. This paper critically examines the impact of Contention Window in TCP congestion
control approaches. The modified TCP congestion control method gives the stability of
congestion window which provides higher throughput and shorter delay than the traditional TCP. Various Backoff algorithms that are used to adjust Contention Window are simulatedusing NS2 along with modified TCP and their performance are analyzed to depict the influence of Contention Window in TCP performance considering the metrics such as throughput, delay, packet loss and end-to-end delay
IMPACT OF CONTENTION WINDOW ON CONGESTION CONTROL ALGORITHMS FOR WIRELESS ADH...cscpconf
TCP congestion control mechanism is highly dependent on MAC layer Backoff algorithms that
predict the optimal Contention Window size to increase the TCP performance in wireless adhoc
network. This paper critically examines the impact of Contention Window in TCP congestion
control approaches. The modified TCP congestion control method gives the stability of
congestion window which provides higher throughput and shorter delay than the traditional TCP. Various Backoff algorithms that are used to adjust Contention Window are simulatedusing NS2 along with modified TCP and their performance are analyzed to depict the influence of Contention Window in TCP performance considering the metrics such as throughput, delay, packet loss and end-to-end delay
OPTIMUM EFFICIENT MOBILITY MANAGEMENT SCHEME FOR IPv6 ijngnjournal
Mobile IPv6 (MIPv6) and Hierarchical Mobile IPv6 (HMIPv6) both are the mobility management solutions proposed by the Internet Engineering Task Force (IETF) to support IP Mobility. It’s been an important issue, that upon certain condition, out of MIPv6 and HMIPv6 which one is better. In this paper an Optimum Efficient Mobility Management (OEMM) scheme is described on the basis of analytical model which shows that OEMM Scheme is better in terms of performance and applicability of MIPv6 and HMIPv6. It shows that which one is better alternative between MIPv6 and HMIPv6 and if HMIPv6 is adopted it chooses the best Mobility Anchor Point (MAP). Finally it is illustrated that OEMM scheme is
better than that of MIPv6 and HMIPv6.
Scheduling and Resource allocation in 802.11ax (WIFI 6)RESHAN FARAZ
--> IIITD Course Project.
--> Implementation of Scheduling and Resource allocation in 802.11ax using NS-3.
-->Modified Largest Weighted Delay First.
--> Comparison of Round Robin Scheduling with Modified Largest Weighted Delay First.
-->Source Code:-https://github.com/reshan9b11/MLWDF_WN_PROJECT
RED: A HIGH LINK UTILIZATION AND FAIR ALGORITHMEditor IJCATR
Internet and its applications are an integral part of our daily life .These days they are widely used for various purposes such as
communication, public services, entertainments, distant educations, etc., each possessing different quality of service (QoS) requirements.
How to provide finer congestion control for network emerges as a major problem. To prevent the problem of congestion control and
synchronization various active queue management (AQM) techniques are used. AQM algorithms execute on network routers and detect
initial congestion by monitoring some functions. When congestion occurs on the link the AQM algorithms detects and provides signals to
the end systems. Various algorithms have been proposed in recent years but RED is one of the most influential techniques among all the
existing ones. This review paper provides the functioning mechanism of the RED technique with the help of its algorithm & its variants
ENHANCEMENT OF TCP FAIRNESS IN IEEE 802.11 NETWORKScscpconf
The usage of fixed buffers in 802.11 networks has a number of disadvantages associated with
it. This includes high delay, reduced throughput and inefficient channel utilisation. To
overcome this, a dynamic buffer sizing algorithm, the A* algorithm has been implemented at
the access point. In this algorithm buffer size is dynamically adjusted depending upon the
current channel conditions and hence delay is reduced and the throughput is maintained. But
in 802.11 networks with DCF collision avoidance mechanism, it creates significant amount of
unfairness between the upstream and downstream TCP flows, with clusters of upstream ACKs
blocking downstream data at the access point. Thus a variation of the Explicit Window
Adaptation (EWA) scheme has been used to regulate the queuing time of the upload clients by
calculating the feedback value at the access point. This creates fairness and increases the number of transmission opportunities for the downstream traffic
A Case Study on Ip Based Cdma Ran by Controlling RouterIJERA Editor
As communication plays an important role in day to day life, the effective and efficient data transmission is to be maintained. This paper mainly deals with implements a congestion control mechanism using Router control method for IP-RAN on CDMA cellular network. The Router control mechanism uses the features of CDMA networks using active Queue Management technique to reduce delay and to minimize the correlated losses. When utilizing these new personal tools and services to enrich our lives, while being mobile, we are using Mobile Multimedia applications. As new handsets, new technologies and new business models are introduced on the marketplace, new attractive multimedia services can and will be launched, fulfilling the demands. Because the number of multimedia services and even more so, the context in which the services are used is numerous, the following model is introduced in order to simplify and clarify how different services will evolve, enrich our lives and fulfill our desires.The proposed paper work is to be realized using Matlab platform.
OPTIMUM EFFICIENT MOBILITY MANAGEMENT SCHEME FOR IPv6 ijngnjournal
Mobile IPv6 (MIPv6) and Hierarchical Mobile IPv6 (HMIPv6) both are the mobility management solutions proposed by the Internet Engineering Task Force (IETF) to support IP Mobility. It’s been an important issue, that upon certain condition, out of MIPv6 and HMIPv6 which one is better. In this paper an Optimum Efficient Mobility Management (OEMM) scheme is described on the basis of analytical model which shows that OEMM Scheme is better in terms of performance and applicability of MIPv6 and HMIPv6. It shows that which one is better alternative between MIPv6 and HMIPv6 and if HMIPv6 is adopted it chooses the best Mobility Anchor Point (MAP). Finally it is illustrated that OEMM scheme is
better than that of MIPv6 and HMIPv6.
Scheduling and Resource allocation in 802.11ax (WIFI 6)RESHAN FARAZ
--> IIITD Course Project.
--> Implementation of Scheduling and Resource allocation in 802.11ax using NS-3.
-->Modified Largest Weighted Delay First.
--> Comparison of Round Robin Scheduling with Modified Largest Weighted Delay First.
-->Source Code:-https://github.com/reshan9b11/MLWDF_WN_PROJECT
RED: A HIGH LINK UTILIZATION AND FAIR ALGORITHMEditor IJCATR
Internet and its applications are an integral part of our daily life .These days they are widely used for various purposes such as
communication, public services, entertainments, distant educations, etc., each possessing different quality of service (QoS) requirements.
How to provide finer congestion control for network emerges as a major problem. To prevent the problem of congestion control and
synchronization various active queue management (AQM) techniques are used. AQM algorithms execute on network routers and detect
initial congestion by monitoring some functions. When congestion occurs on the link the AQM algorithms detects and provides signals to
the end systems. Various algorithms have been proposed in recent years but RED is one of the most influential techniques among all the
existing ones. This review paper provides the functioning mechanism of the RED technique with the help of its algorithm & its variants
ENHANCEMENT OF TCP FAIRNESS IN IEEE 802.11 NETWORKScscpconf
The usage of fixed buffers in 802.11 networks has a number of disadvantages associated with
it. This includes high delay, reduced throughput and inefficient channel utilisation. To
overcome this, a dynamic buffer sizing algorithm, the A* algorithm has been implemented at
the access point. In this algorithm buffer size is dynamically adjusted depending upon the
current channel conditions and hence delay is reduced and the throughput is maintained. But
in 802.11 networks with DCF collision avoidance mechanism, it creates significant amount of
unfairness between the upstream and downstream TCP flows, with clusters of upstream ACKs
blocking downstream data at the access point. Thus a variation of the Explicit Window
Adaptation (EWA) scheme has been used to regulate the queuing time of the upload clients by
calculating the feedback value at the access point. This creates fairness and increases the number of transmission opportunities for the downstream traffic
A Case Study on Ip Based Cdma Ran by Controlling RouterIJERA Editor
As communication plays an important role in day to day life, the effective and efficient data transmission is to be maintained. This paper mainly deals with implements a congestion control mechanism using Router control method for IP-RAN on CDMA cellular network. The Router control mechanism uses the features of CDMA networks using active Queue Management technique to reduce delay and to minimize the correlated losses. When utilizing these new personal tools and services to enrich our lives, while being mobile, we are using Mobile Multimedia applications. As new handsets, new technologies and new business models are introduced on the marketplace, new attractive multimedia services can and will be launched, fulfilling the demands. Because the number of multimedia services and even more so, the context in which the services are used is numerous, the following model is introduced in order to simplify and clarify how different services will evolve, enrich our lives and fulfill our desires.The proposed paper work is to be realized using Matlab platform.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Congestion control in computer networks using a modified red aqm algorithmeSAT Journals
Abstract Congestion control plays an important role in network resource management in very large networks with heavy traffic. Active Queue Management (AQM) algorithms are one of the approaches to resolve the congestion problems. Majority of AQM algorithms mainly focus on single queued links. The input queued switches are limited in throughput and output queued switches require a large speedup factor so our attention is directed towards Combined Input and Output Queued (CIOQ) switches. A simple modification to the RED AQM algorithm is proposed in this paper in order to account for the presence of both input and output queues in the switch. The weighted sum of input and output queue lengths are specifically used as the congestion measure instead of just the output queue length. The average backlog in the switch is significantly reduced in the low speedup region by using our modified algorithm as compared to RED without this modification. Simulations show that the loss rate in the modified RED slightly larger than that in traditional RED but the output queue length in modified RED is tremendously reduced. The congestion measure which is computed using weighting factor results in reduction of the average backlog. Using our modified algorithm simulations indicate improvement in the queue length and switch utilization. Keywords: Combined Input and Output Queued (CIOQ), Active Queue Management (AQM), Random Early Detection (RED), congestion, congestion control
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Comparative Analysis of Drop Tail, Red and NLRED Congestion Control Algorithm...EvaObinna
Congestion in a network may occur when the load on the network is greater than the capacity of the network and consequently, performance degrades. Congestion control is a technique and mechanisms that can either prevent congestion before it happens, or remove congestion after it has happened. This work presents a comparative analysis of Drop Tail, RED and NLRED congestion control algorithm and performed a simulation experiment to show their relative effectiveness. The experiment was done using NS2 simulator on the basis of End-to-End Delay, Throughput, Packet Drop, and Packet Delivery Ratio in a wired network. The simulation result showed that NLRED performs best in high congestion network, while in low cohesive network, Drop Tail gives a good result. Drop Tail, RED and NLRED was also analysed in real audio traffic and the entire results showed that in congested network, NLRED and RED are better while in low congested network Drop Tail is better. This is because in heavy congested network, congestion avoidance mechanism aids the network to gain better performance while in low congested network unnecessary computation avoidance mechanisms degrades the performance of the network. If parameters are set effectively in RED, it will be the best queuing mechanism for that particular network. However, it is of great importance to know which congestion control mechanism is suitable for each network and traffic.
Abstract: CHOKe is a simple and stateless active queue management (AQM) scheme. Highly attractive property of Choke is that it can protect responsive TCP flows from unresponsive UDP flows. Packets currently queued in buffer, to penalize the high bandwidth flows. It can be implemented by using RED algorithm. In RED algorithm when packets arrives at a congested router. CHOKe draws a packet at a random from the FIFO buffer and compares it with the arriving packet. If both belong to same flow, then they are both dropped; else randomly chosen packet is left intact and arriving packet is admitted into the buffer with a probability that depend on the level of congestion. These algorithms are typically implemented in the transport protocols (e.g., TCP) of end-hosts. To ensure global fairness, such schemes require all users to adopt them and respond to network congestion properly.Keywords: CHOKe, Random Early Detection (RED), Congestion.
Title: Ephemeral Performance of Choke
Author: Suhitha K.C
ISSN 2350-1022
International Journal of Recent Research in Mathematics Computer Science and Information Technology
Paper Publications
Efficient and Fair Bandwidth Allocation AQM Scheme for Wireless NetworksCSCJournals
Heterogeneous Wireless Networks are considered nowadays as one of the potential areas in research and development. The traffic management’s schemes that have been used at the fusion points between the different wireless networks are classical and conventional. This paper is focused on developing a novel scheme to overcome the problem of traffic congestion in the fusion point router interconnected the heterogeneous wireless networks. The paper proposed an EF-AQM algorithm which provides an efficient and fair allocation of bandwidth among different established flows. Finally, the proposed scheme developed, tested and validated through a set of experiments to demonstrate the relative merits and capabilities of a proposed scheme
Review on buffer management schemes for packet queues in wired & wireless net...IJERA Editor
Mobile AdHoc Network (MANET) is a wireless network with a set of mobile nodes that can communicate with
each other with no access point and without any fixed infrastructure. But mobile devices usually have limited
resources (battery power, memory, CPU) which limit their transmission range. Hence, in order to conserve the
limited resource, it is highly desirable that transmission should be as efficient as possible. MANET can be
implemented in any environment because of its dynamic nature. For routing of information packets queuing is
done at the buffer and transferred through intermediate nodes to the destination on priority basis which help to
improve the overall network performance. This paper provides a review of various buffer management schemes
for packet queues in wired & wireless networks (specialy MANET).
CONTROLLING DELAY AT THE ROUTER BUFFER USING MODIFIED RANDOM EARLY DETECTIONIJCNCJournal
Active Queue Management (AQM) methods are used to manage the buffer of the network routers and avoid the problems caused by network congestion, especially packet loss. Among various AQM methods that have been proposed in the literature, Random Early Detection (RED)method has proved to stabilize the network performance under various traffic loads. However, as the primary concern of RED is to avoid loss when the router buffer overflowed, RED harms the delay at the router and increases the latency. Given that reducing delay is critical to some applications, such as online conferencing and broadcasting, RED needs to be adjusted to ease the delay problem. In this paper, RED is improved by monitoring the delay at the router buffer and implementing packet dropping to handle the issue of network delay and enhance the network
performance. Accordingly, the modified method calculates and used a delay parameter with the RED to reduce the delay while maintaining the desirable RED’s characteristics. The experimental results showed that the proposed Delay-Controller Random Early Detection (DcRED) improved network performance under various traffic loads. Compared to RED, DcRED results in less delay, while maintaining the loss and
dropping rates.
Improving Performance of TCP in Wireless Environment using TCP-PIDES Editor
Improving the performance of the transmission
control protocol (TCP) in wireless environment has been an
active research area. Main reason behind performance
degradation of TCP is not having ability to detect actual reason
of packet losses in wireless environment. In this paper, we are
providing a simulation results for TCP-P (TCP-Performance).
TCP-P is intelligent protocol in wireless environment which
is able to distinguish actual reasons for packet losses and
applies an appropriate solution to packet loss.
TCP-P deals with main three issues, Congestion in
network, Disconnection in network and random packet losses.
TCP-P consists of Congestion avoidance algorithm and
Disconnection detection algorithm with some changes in TCP
header part. If congestion is occurring in network then
congestion avoidance algorithm is applied. In congestion
avoidance algorithm, TCP-P calculates number of sending
packets and receiving acknowledgements and accordingly set
a sending buffer value, so that it can prevent system from
happening congestion. In disconnection detection algorithm,
TCP-P senses medium continuously to detect a happening
disconnection in network. TCP-P modifies header of TCP
packet so that loss packet can itself notify sender that it is
lost.This paper describes the design of TCP-P, and presents
results from experiments using the NS-2 network simulator.
Results from simulations show that TCP-P is 4% more
efficient than TCP-Tahoe, 5% more efficient than TCP-Vegas,
7% more efficient than TCP-Sack and equally efficient in
performance as of TCP-Reno and TCP-New Reno. But we can
say TCP-P is more efficient than TCP-Reno and TCP-New
Reno since it is able to solve more issues of TCP in wireless
environment.
MINIMALLY BUFFERED ROUTER USING WEIGHTED DEFLECTION ROUTING FOR MESH NETWORK ...VLSICS Design
The scalability, modularity and massive parallelism exhibited by Network on chip(NoC) interconnects
make them highly suitable for the inter core communication framework of multiprocessor system-on-chip
(MPSoC) designs. Routers play the most vital role in transferring flits through the network, hence efficient
microarchitecture and cost effective routing algorithms are highly essential for modern NoC routers.
Elimination of buffers and deflection routing help to achieve energy and area efficiency of these routers.
The advantages of bufferless and buffered designs can be combined by using a minimum number of side
buffers to store a fraction of deflection flits in the router. In this paper, we propose a routing algorithm
based on weighted deflection of flits for minimally buffered deflection routers. Evaluations on 4x4 and 8x8
mesh NoC using synthetic workloads as well as benchmark applications demonstrate that deflection rate
and average network latency are significantly reduced in comparison with the state of the art NoC routers.
Performance analysis of the newly proposed algorithm shows that the network saturation point improves
by 26% compared to earlier designs in this domain
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
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Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
2. Presentation Outlines
General Idea of the Project.
General background about different AQM’s (RED & DropTail)
Modified RED AQM
Project Implementation Details
Future Work
Testing
Issues
Mathematical Elaboration
3. Abstract
The project focuses on how congestion control and queue
management techniques have evolved over time and being
modified to minimize the rate of packet loss. Extensive relevant
research has been done on the existing AQM’s and from the midst
of RED, our algorithm has evolved. The key idea is to modify the
existing RED algorithm to achieve stabilization in Queue length,
decrease in packet loss rate at routers and increased throughput in
comparison to RED. The packet probability marking function of RED
has been modified into four different functions and the results and
effects on various parameters like Queue length, packet loss etc
have been simulated and compared. The design rationale of RED
has been studied and enhanced to achieve better stabilized queue
and throughput.
4. Need…
Due to the enormous growth of the internet, demands for access
from multiple users have increased and the request for new services
for its application have also increased significantly. Due to this ,
there have been an increase in packet loss rates and drop in
network efficiency. The problem has been well discussed over
several years, still conventional Active Queue Management
Algorithms cannot provide low complexity deployment.
5. Background - General
In today’s networks, transport layer protocols are the one
responsible for congestion avoidance
When there is congestion in the router and its queue gets over flown
, it drops packets from the tail until there is space to receive new
packets in the buffer
The protocol is completely transparent to the hosts, they see it as
“Black Box”. Their only indication of congestion is packet loss
7. Drop Tail
The traditional technique for managing router is the method known as "tail
drop“.
This method has served the Internet well for years, but it has two important
drawbacks:
LOCK OUT
Drop-tail routers treat bursty traffic poorly
Traffic gets synchronized easily allows a few flows to monopolize the queue
space
TCP-GLOBAL SYNCHRONIZATION
In computer networks It can happen to TCP/IP flows during periods of
congestion because each sender will reduce their transmission rate at the
same time when packet loss occurs.
8. Other Problems in real network
scenarios
TCP global Synchronization
Congestive Collapse
Network protocols which use aggressive retransmissions to compensate
for packet loss tend to keep systems in a state of network congestion
even after the initial load has been reduced to a level which would not
normally have induced network congestion. Thus, networks using these
protocols can exhibit two stable states under the same level of load. The
stable state with low throughput is known as congestive collapse
Fairness among different flows
9. Active Queue Management
In summary, an active queue management mechanism can provide the
following advantages for responsive flows:
1. Reduce number of packets dropped in routers
By keeping the average queue size small, active
queue management will provide greater capacity to
absorb naturally- occurring bursts without dropping
packets. Without active queue management, more
packets will be dropped when a queue does overflow.
2. Provide lower-delay interactive service
By keeping the average queue size small, queue
management will reduce the delays seen by flows.
This is particularly important for interactive
applications such as short Web transfers, Telnet
traffic, or interactive audio-video sessions,whose
subjective (and objective) performance is better when
the end-to-end delay is low.
3. Avoid lock-out behavior
Active queue management can prevent lock-out
behavior by ensuring that there will almost always be
a buffer available for an incoming packet. For the
same reason, active queue management can prevent a
router bias against low bandwidth but highly bursty
flows.
10. RED(Random Early Detection)
RED was designed with the objectives to
(1) minimize packet loss and queuing delay,
(2) avoid global synchronization of sources,
(3) maintain high link utilization, and
(4) remove biases against bursty sources.
RED gateways require the user to specify five parameters: the
maximum buffer size or queue limit (QL), the minimum (minth) and
maximum (maxth) thresholds of the "RED region", the maximum
dropping probability (maxp), and the weight factorused to
calculate the average queue size (wq).
11. RED – Cont.
Early packet dropping starts when the average queue size
exceeds minth.
RED was specifically designed to use the average queue size
(avg), instead of the current queue size, as a measure of incipien
congestion, because the latter proves to be rather intolerant of
packet bursts.
avg is calculated as an exponentially weighted moving average
using the following formula:
avg i = (1 - wq) × avgi-1 + wq × q
16. Comparison on the basis of
throughput
At Node 4:
Using RED: 0.241504MBytes/sec
Using DropTail: 0.207008MBytes/sec
At Node 5:
Using RED : Avg Throughput 0.20084Mbytes/sec
Using DropTail: Ang Throughput 0.184832Mbytes/sec
19. The Algorithm
What’s About to change ?...
Pb = Pmax*(avg – th_min)/(th_max-th_min)
Pa = Pb / (1 – count*Pb)
RED calculates the probability of dropping a packet by 2 steps
when average queue size falls in between th_min and th_max. The
first step is to calculate a probability called Pb, which is based on
the formula below,
It can be seen that the probability Pb is calculated based
on a linear function.
In the second step, RED counts the number of packets
have gone through the gateway (count) since last
packet is dropped from the flow and apply the following
formula,
20. SUBSYTEMS
What’s New ?..
In this part, we modified the first step by applying 2
different functions to calculate Pb and compare the
results. The curves for the 2 functions are roughly in
left.
2
21. Mathematical Representation :
Original function:
Modified Functions:
V1: Pb = Pmax*(m*log(v_ave) + n)
V2: Pb = Pmax*(m*exp(v_ave)+n)
Pb = Pmax*(v_a * v_ave + v_b)
where v_a = 1.0 / (th_max – th_min), v_ave is the average queue size, and v_b = -th_min / (th_max –
th_min).
22. SYSTEM INTEGRATION
Changes in the code
Add a variable func to the data structure edp.
Bind the variable in REDQueue constructor
REDQueue::REDQueue
bind (“function_”,&edp_.func)’
Calculate p_new_probability function
Make changes in ns-default.tcl
Queue/RED set function_ 0
29. FINDINGS & CONCLUSION
Queue Size
From the plot, we can see that v1 keeps the
average queue size at a lower level than regular
RED, while v4 keeps the average queue size at a
higher level than regular RED. This is expected as
v1 is always above the original linear function
given the same average queue size value in the
range of [th_min, th_max], in other words, v1 is
more aggressive in terms of dropping packets
when the average queue size is between th_min
and th_max. On the contrast, v4 is less aggressive
than regular RED.
30. Packet Loss
From the simulation for loss packets, we can see that V4 ensures less
packet drop than regular RED and vice versa in case of V1, in which
packet is dropped at a higher rate than V1 and regular RED algorithm.
Same can be deduced for V2 and V3, with V2 being on the higher side.
31. Scenario[minp,maxp] Function/AQM Packet Sent Packet Lost % Packet Loss
[15,45] RED 18736 27 1.44
[15,45] Concave function (v1) 18717 23 1.22
[15,45] Piece wise Linear(v2) 18698 28 1.49
[15,45] Piece wise Linear(v3) 18459 27 1.46
[15,45] Convex function (v4) 18194 44 2.41
[20,60] RED 18671 25 1.33
[20,60] Concave function (v1) 18712 28 1.49
[20,60] Piece wise Linear(v2) 18636 26 1.39
[20,60] Piece wise Linear(v3) 18373 33 1.79
[20,60] Convex function (v4) 18025 33 1.83
[25,75] RED 18645 29 1.55
[25,75] Concave function (v1) 18657 26 1.39
[25,75] Piece wise Linear(v2) 18648 24 1.28
[25,75] Piece wise Linear(v3) 18579 25 1.34
[25,75] Convex function (v4) 17773 20 1.12
[30,90] RED 18511 26 1.40
[30,90] Concave function (v1) 18564 25 1.34
[30,90] Piece wise Linear(v2) 18564 27 1.45
[30,90] Piece wise Linear(v3) 18522 22 1.18
[30,90] Convex function (v4) 17773 20 1.125
Table Showing Packet Loss For differect Scenarios & Functions
32. Throughput
From the simulations, we can see that V4 function ensures higher
throughput than regular RED and V1 function.
33. Requirement specification
Functionality
The purpose of this AQM is to stabilize the Average Queue length at
routers.
External Interface
The AQM can be simulated in Network Simulator 2.34 and higher.
Unix environment will be used to simulate the Otcl and C++ classes.
The interaction of software will be through command line interface (like
Unix and NS2)
34. Required Performance
The complexity of the algorithm is O(N), where N is the total number of
routers participating in the exchange of Data at a particular time.
The robustness of the algorithm is tested and simulated with 50 Nodes
including two main congestion control routers.
The simulated time with fixed delay of 100ms, proved to be under 1 sec.
Quality Attributes
The design rationale of Modified RED AQM, is made closely with the actual
RED AQM, Hence all the standard measures of correctness, maintainability
and security have been followed strictly.
Design Constraints imposed on the implementation
The Testing has been done under a simulated scenario, keeping the delay in
consideration as close as possible to the real life scenario.
35. ISSUES
Installing Ns2.34 in Ubuntu 13.04 (resolved)
Appropriate parameters for running RED. Keeping the number of
nodes high to observe the changes. Leading to overhead.
Appropriate parameters for running RED. Keeping the number of
nodes high to observe changes in throughput.
It was observed that results in a particular scenario [20,60] beg to
differ slightly from other scenarios.
36. COMPLEXITY & TESTING OF MODULE
Determining Complexity
Most of the algorithms claim that they can provide fair sharing among different flows
without imposing too much deployment complexity. Most of the proposals focus on
only one aspect of the problem (whether it is fairness, deployment complexity, or
computational overhead), or fix the imperfections of previous algorithms, and their
simulations setting are different from each other. These all make it difficult to evaluate,
and to choose one to use under certain traffic load.
The complexity can be defined in terms of the following:
DEPLOYMENT COMPLEXITY
The modified version of RED offers low deployment complexity as changes can be done
in the original RED algorithm only and no new components need to be installed.
COMPUTATIONAL OVERHEAD
Each arriving packet at the respective Router triggers the algorithm(same as RED)
BIG-O-NOTATION
O(Nt); N-> is the number of arriving packet arriving at the routers for a particular flow.
The Algorithm is designed to work with the main routers
37. Performance evaluation
By comparison
The comparison of the obtained queue length was done with the original
RED AQM.
38. By comparison
ORIGINAL RED
MODIFIED CONCAVE AQM MODIFIED CONVEX AQM
Scenario :
Queue/RED set thresh_ 15
Queue/RED set maxthresh_ 45
RESULTS(Average Queue Length):
ORIGINAL RED: 130(approx)
CONCAVE RED: 100 (approx)
CONVEX RED 155(approx)
39. TYPE OF TEST WILL TEST BE
PERFORMED
COMMENTS/EXPLA
NATION
SOFTWARE
COMPONENT
Requirement
Testing
Yes Involves testing of
all the required
components
Existing RED &
Droptail AQM
Unit yes Unit of Algorithms
including Average
queue length, loss
rates etc
RED
Integration Yes Integration of the
changes done in
the original RED
RED, Modified RED
Performance Yes Does not crash for
high number of
nodes
Modified RED
Stress Yes No. of load for
which the
algorithm works
fine
Modified RED
Compliance NO Standards
maintained by RED
Modified RED
Security NO Same standards as
maintained by RED
Modified RED
Load Yes Tested for 50 +
nodes
Modified RED
Role Name Specific
Responsibilities
Developer &
Tester
Siddharth
Nawani
Working on
developing
and
integration of
modules.
Testing of the
whole
Algorithm
40. The average queue length was tested for four different scenarios
Scenario 1:
Queue/RED set thresh_ 15
Queue/RED set maxthresh_ 45
Scenario 2:
Queue/RED set thresh_ 20
Queue/RED set maxthresh_ 60
Scenario 3:
Queue/RED set thresh_ 25
Queue/RED set maxthresh_ 75
Scenario 4:
Queue/RED set thresh_ 30
Queue/RED set maxthresh_ 90
41. Risk Analysis & Mitigation Plan
Risk
Potential
Impact on
Project
Success
L/M/H
Likelihood of
Occurrence
L/M/H
Mitigation Plan
1.Project Size H H Decomposition(Break into smaller
phases
Phased implementation)
2. Project Scope H H Decomposition
Add another analysis phase
Detailed specifications
Early prototype/review of functionality
Add more time to the project schedule.
3. Project Decision-Making L(no sponsor
and one
decision
maker)
L The Coder as well as the project
implanter take care of this
4. Environmental State (Networking) H(it’s volatile
and yest to
be
deployed)
H Additional testing, particularly stress
testing
Training on new environment
Find other projects using a similar
environment to compare notes
Get a prototype deployed ASAP on new
environment
5. Team’s Experience M(Since no
similar
Project has
been done)
M Less effect since the project team
comprises of one member only.
Cross referencing results with other
verified results
6. Project Schedule L(Since the
process is still
in
developmen
t phase)
L Supplement resources (outside
consultants, other groups)