A selective delayed channel access (SDCA) for the high-throughput IEEE 802.11n

Abstract— In this paper we investigate the potential benefits of a selective delayed channel access algorithm (SDCA) for the future IEEE 802.11n based high-throughput networks. The proposed solution aims to resolve the poor channel utilization and the low efficiency that EDCA’s high priority stations adhere due to shorter waiting times and consequently to the network’s degrading overall end performance. The algorithm functions at the MAC level where it delays the packets from being transmitted by postponing the channel access request, based on their traffic characteristics. As a result, the flow’s average aggregate size increases and consequently so is the channel efficiency. However, in some situations we notice that further deferring has a negative impact with TCP applications, thus we further introduce a traffic awareness feature that allows the algorithm to distinguish which flows are using the TCP protocol and override any additional MAC delay. We validate through various simulations that SDCA improves throughput significantly and maximizes channel utilization

Simulation Based Comparative Performance Analysis of OSPF and EIGRP Routing Protocols

In the computer networks, the data traffic transmission is based on the routing protocol which select the best routes between two nodes. Variety of routing protocols are applied to specific network environments. Routing protocol\ud is taking a crucial role in the modern communication networks and its functionality is to determine how the routers communicate with each other and forward the packets through the optimal path from source to destination node. In\ud this paper, two typical types of routing protocol are chosen as the simulation samples: EIGRP and OSPF. Each of them has different architecture, route delays and convergence characteristics. The aim is to present a simulation based comparative analysis between EIGRP and OSPF for real time applications considering realistic backbone communication links and existing subnets. The\ud evaluation of the proposed routing protocols is performed based on the widely accepted quantitative metrics such as: convergence time, end-to-end delay, jitter, packet loss and throughput of the simulated network models. Tractable\ud conclusions and discussions are presented for each protocols and multi-protocol network implementations

Performance and Analysis of Transfer Control Protocol Over Voice Over Wireless Local Area Network

A thesis presented to the faculty of the College of Science and Technology at Morehead State University in partial fulfillment of the requirements for the Degree Master of Science by Rajendra Patil in August of 2008

Network Simulation Cradle

This thesis proposes the use of real world network stacks instead of protocol abstractions in a network simulator, bringing the actual code used in computer systems inside the simulator and allowing for greater simulation accuracy. Specifically, a framework called the Network Simulation Cradle is created that supports the kernel source code from FreeBSD, OpenBSD and Linux to make the network stacks from these systems available to the popular network simulator ns-2. Simulating with these real world network stacks reveals situations where the result differs significantly from ns-2's TCP models. The simulated network stacks are able to be directly compared to the same operating system running on an actual machine, making validation simple. When measuring the packet traces produced on a test network and in simulation the results are nearly identical, a level of accuracy previously unavailable using traditional TCP simulation models. The results of simulations run comparing ns-2 TCP models and our framework are presented in this dissertation along with validation studies of our framework showing how closely simulation resembles real world computers. Using real world stacks to simulate TCP is a complementary approach to using the existing TCP models and provides an extra level of validation. This way of simulating TCP and other protocols provides the network researcher or engineer new possibilities. One example is using the framework as a protocol development environment, which allows user-level development of protocols with a standard set of reproducible tests, the ability to test scenarios which are costly or impossible to build physically, and being able to trace and debug the protocol code without affecting results

Performance comparison of transmitting jumbo frame on Windows and Linux System

IPv6 is the successor of IPv4, the current Internet Protocol that runs out its address. It offers some improvements including simpler header format and extension header resulting in faster transmission of IP packets. However, IPv6 is a network layer protocol that requires lower layer services. IP packets from the network layer pass to data link layer to be encapsulated by layer 2 headers and trailer to become frames. Ethernet is the most widely used data link layer protocol in the current network devices. The technology is always improved to support high speed transmission. However, from standard Ethernet until ten gigabit Ethernet, the size of MTU remains unchanged at 1500 Bytes. This prevents the network from gaining an optimum performance on transmitting IP packets and operating systems cannot take full advantage of the high-speed performance of Gigabit Ethernet. This research aims to implement the transmission of IPv6 packets using jumbo frame on a test-bed environment. The implementation can be used to justify the impact of jumbo frame on the network as well as operating systems performance. The results prove that the OS used on implementation of jumbo frame affects on the network performance. The highest percentage of increasing throughput is 33.6% when both sender and receiver are running Windows. The decreasing delay by 54.36% was happened when using Linux in sender and Windows in receiver