Mohammed M. Kadhum

Fast Congestion Notification mechanism for ECN-capable routers

While computer networks go towards dealing with varied traffic types with different service requirements, there is a necessity for modern network control mechanisms that can control the network traffic to meet the users’ service requirements. Optimizing the network utilization by improving the network performance can help to accommodate more users and thus increase operators’ profits. Controlling the congestion at the gateway leads to better performance of the network. Sending congestion signal sooner can be of great benefit to the TCP connection. In this paper, we propose Fast Congestion Notification (FN) mechanism which is a new method for managing the gateway queues and fast sending of congestion signal to the sender. We tested our mechanism on Explicit Congestion Notification (ECN) packets which have higher priority; we achieved good results in terms of faster congestion signal propagation and better network utilization. Our analysis and simulations results show that the use of FN over TCP connections sharing one bottleneck can improve the throughput, having less loss, less delay time, and better network utilization.

The effect of ECN on short TCP sessions

Explicit congestion notification (ECN) is a method for informing the sender about the network congestion. ECN activation on gateways marks packets instead of dropping them thus lead to faster congestion signal propagation and good network utilization. ECN mechanism does not require generation of additional traffic at the router and can be implemented in the data path of routers. In this paper, we use ns2.29 to investigate the effect of ECN on short TCP sessions using random early detection (RED) gateways. We evaluate the effect of a number of parameters, including buffer size, window size, increase/decrease parameters, size of transfer and RED parameters. We verify that the use of ECN for a slightly big number of short TCP sessions sharing one bottleneck can improve the throughput with fairly less delay.

Pause Time Optimal Setting for AODV Protocol on RPGM Mobility Model in MANETs

For the last few years, a number of routing protocols have been proposed and implemented for wireless mobile Ad hoc network. The motivation behind this paper is to discover and study the pause time effects on Ad hoc on Demand Distance Vector (AODV) protocol and find out the node pause time optimal setting for this protocol where Reference Point Group Mobility (RPGM) model uses as a reference model. In order to come across the best performance of a particular routing protocol, there a need to examine a number of parameters with different performance and analyze the optimal setting of that protocol and its network configuration environment. This experiment, the speed is fixed with 20 ms in all scenarios while the pause time is varying from scenario to another to observe the optimal setting of the pause time on protocol’s performance in this configuration. The outcome of the experiment are analyzed with different parameters such as varying number of nodes, increasing connections, increasing pause time and discussed the effects of the pause time. The results have shown that the value of the pause time can be affecting the performance of the protocol. In the experiment, we found that the lower pause time give better performance of the protocol. However, this paper is a part of ongoing research on AODV protocol in link failure. Thus, it is important to figure out the factors which can be involved the performance of the protocol.

Energy Efficiency Mechanisms Using Mobile Node in Wireless Sensor Networks

A traditional network consists of gateway sensors which transmit data to the base stations. These nodes are considered bottlenecks in multihop-networks as they transmit their data as well as data from other nodes and hence they deplete faster in energy. One way to optimize energy efficiency in a WSN is to deploy a mobile base station which could collect data without a need for gateway nodes, and hence the multihop bottleneck would be minimized. We compare these two variations of WSN, one consisting of the multihop approach with gateway nodes, and we propose the other network structure, whereby a mobile base station collects data individually from each node using double Fermat’s spiral model.

A study of ECN effects on long-lived TCP connections using red and Drop tail gateway mechanisms

Rapid growth of Internet traffic and the increase of new user applications authorize the development of new internet infrastructure. Congestion remains the major problem that affects the Internet service quality. Avoiding packet drops keeps network bandwidth and permits congestion signals to be propagated faster. Sending congestion information is essential to the network performance. Using Explicit Congestion Notification (ECN) to notify the source about the network congestion can result in sending congestion signal faster so that the sender can reduce its congestion window sooner which leads to better network utilization. When ECN is enabled on routers, they mark packets instead of dropping them. ECN mechanism does not require creation of additional transfer at the router and can be applied in the data path of routers. . In this article, we study the behavior of ECN-capable TCP and examine the effect of ECN on long-lived TCP connections using Random Early Detection (RED) and Drop tail gateway mechanisms. We estimate the gain introduced by ECN, in terms of throughput, with different sets of number of TCP users and a point of congestion. Our analysis and simulations results show that the use of ECN over long-lived TCP connections sharing a bottleneck can improve the overall throughput, having less loss, less delay time, and better network utilization

Mitigation of Wormhole Attack in Wireless Sensor Networks

Wireless Sensor Networks is consisting of number of limited sensor devices which are communicated over the wireless media and it offers variety of solutions to military, healthcare and industrial applications. As sensor devices are resource restricted, the networks exposed to different types of attacks and conventional techniques against these attacks are not desirable and consequently utilizing WSNs with security services is a challenging. One severe attack, to detect and mitigate, is wormhole attack in which traffic will be forwarded from a location of network to another through the wormhole tunnel. In this paper we review WSN concepts and applications and discuss about security issues and challenges.

Performance Enhancement of DCCP TCP-like over Long Delay Link Networks

The performance of DCCP TCP-like degrades significantly over long delay link networks. Despite the TCP-like congestion control mechanism follows the TCP SACK, the performance is really affected by the congestion window growth algorithms as employed by Jacobson based TCP variants. In this paper, all the experiments are done using Network Simulator ns-2, and we manipulated the congestion window size drop during congestion avoidance phase to enhance the performance of DCCP TCP-like over long delay link networks. Instead of halving the current congestion window when congestion events are detected, the reduction of current congestion window drop has been shown to improve the DCCP TCP-like throughput with minimal drop packet percentage.

A demonstration of the FN packet marking probability

The effectiveness of queue management mechanisms relies on how good their control decisions will help in satisfying their goals regarding congestion avoidance and control. These decisions are implemented and compelled during the design of the packet mark probability and the mark activation functions. The design of Fast Congestion Notification (FN) drop/mark probability function enables the two control decisions, packet admissions and congestion control directing, to be made along with each other. This permits sending congestion avoidance notification as early as required even if the queue is almost empty, and preventing congestion notification even if the queue is almost full but the arrival rate is controllable. This leads to good buffer utilization and proper congestion detection. This paper demonstrates the drop/mark probability functions that the fast FN policy would exercise for different values of optimal queue size, and also for a specific optimal queue size value.

Redirect Link Failure Protocol Based on Dynamic Source Routing for MANET

Ad hoc networks are characterized by multi-hop wireless connectivity. Due to frequent topology changes in wireless ad hoc networks, designing an efficient and dynamic routing protocol is a very challenging task,and it has been an active area of research. This work is part of ongoing research on the link failure problem caused by the node’s mobility in Dynamic Source Routing (DSR) protocol. In this paper, we propose an extension of DSR protocol called Redirect Link Failure Protocol (DSR-RLFP) in order to solve link failure and avoid propagation route error message back to the source upon link failure in a different way from the existing solution. RLFP protocol contains two models namely, Link Failure Prediction Model and Link Failure Solution Model. The main benefit of RLFP is to reduce the frequent route discovery process after link failure happened, which leads to save network resources.

‘NetAccess’: Networked access to computerized-system using Iris

Based on the available secured files and information in the companies; they need to be secured by a very high system. Currently, most of companies are accessed by normal keys in order to access the offices. But, those keys might be lost or stolen. In addition, those doors can be hacked easily by thieves. This raises a need to improve security of such information by limiting access only to those who have authorization to do so. The traditional means, as well as biometric traits other than iris, do provide such control; yet they still have several limitations in verifying the identity of individuals. In this presents the design of an Iris Recognition System for accessing Building and Control System