Knowledge Base

Title Authors Last Update Category
Performance Evaluation of TCP over IEEE 802.11 WLANs Sachin Goel

Transmission Control Protocol (TCP) is a communication protocol that is used to provide reliable data delivery between hosts. As TCP is the most highly used transport-layer protocol, many have worked on addressing the issue of performance. Performance issues have been studied in various environments, especially when using 802.11 Wireless Local Area Networks (WLANs). Wireless networks are prone to a higher number of packets loss and corruption. 802.11 WLANs have an equivalently fast acknowledgement mechanism as TCP to ensure reliability of traffic over it. This duplication of functionality between TCP and 802.11 WLAN creates unexpected behaviors that can result in high costs in terms of overall performance. A significant amount of analytical and simulation work has been done in the past to study the behaviour of TCP over 802.11 WLANs. The main contribution of this work is the analysis of TCP interaction in an 802.11 WLAN topology by using real commercial-grade equipments. A testing methodology is designed to do the quantitative performance evaluation in a network topology consisted of wired as well as a wireless connection. The methodology contains test scenarios with different configurable settings on an Access Point (AP) and various controlled impairments in the network topology such as latency, packet drop, noise interference, etc. The performance of TCP is measured in terms of the throughput. This work provides a comprehensive set of experiments to study the behaviour of TCP over 802.11 WLANs. The results can provide insight into the performance cost associated with TCP traffic on 802.11 WLANs under different network environments and configurations on the AP. The results of this work thus have a value to equipment manufacturers and network operators.

September 1, 2006 Theses
PoE Technical FAQ

PoE FAQ's

September 23, 2014 External Links
PPP Design, Implementation, and Debugging, Second Edition James Carlson

From the back cover: "PPP Design, Implementation, and Debugging, Second Edition, is a complete and convenient resrouce for netowrk system designers and administrators. This book contains everything you need to know to work with the Point-to-Point Protocol (PPP), one of the most important Internet protocols in use today. Inside you'll find clear explanations of the underlying concepts, practical implementation information, and valuable debugging techniques to keep your PPP connections running smoothly, efficiently, and uninterrupted."

June 26, 2012 Recommended Textbooks
Presentation on the 10GEC Bob Noseworthy

Presented at the 10Gigabit Ethernet User Conference, Nov 1 2002

November 5, 2002 Tutorials
Proceedings of the 5th Annual Linux Showcase & Conference Ashish Palekar, Narendran Ganapathy, Anshul Chadda, Robert D. Russell

Design And Implementation Of A Linux SCSI Target For Storage Area Networks.

June 29, 2012 White Papers
PTP Background and Overview Jeff Laird

Terms used when discussing PTP

June 28, 2012 White Papers
QOS Over ADSL Praveen Reguraman

Today's digital economy, dominated and driven by the growing commercial outlook of the Internet, has stimulated the demand for broadband networking as well as Quality of Service (QoS) architectures to achieve application performance and user satisfaction. Asymmetric Digital Subscriber Line (ADSL) is gaining prominence as a cost-effective broadband access solution for high speed Internet access, being widely deployed nationwide. The promise and potential to handle applications like Video on Demand over ADSL has set the stage to engineer and evaluate QoS in ADSL systems. As a first step in this direction, the various issues applicable to QoS over ADSL are discussed and a test setup was developed to evaluate the QoS metrics with respect to the physical layer characteristics of ADSL systems. The results of the preliminary set of experiments and the insight gained from these will be presented along with recommendations for future work.

December 7, 2000 Theses
Quality of Service Testing Methodology Ankur Chadda

Typically, a network service provider offers best-effort service to customers and Quality of Service (QoS) is provided only by network over provisioning. When traffic bursts cause congestion, this default approach does not always provide an acceptable solution. As the trend in networking is convergence of voice, video and data, it is important to differentiate traffic into high and low priority classes through QoS mechanisms. To deliver differentiated QoS, the routers utilize classification and sometimes remarking of the traffic. Based on service agreements with the customer, a certain class of traffic is then given more resources by the router. Evaluation of the results of these methods and approaches on the network performance is very important to device designers, network evaluators, network administrators, network operators and others involved. To study the effects of QoS solutions/techniques on the traffic, methods for testing need to be developed. The objective of this thesis is to propose methods of measuring QoS metrics like throughput, latency, and jitter for different types of traffic through a device. Classification and remarking were observed to put extra load on a device. For some devices, the performance deteriorates when classification and remarking are enabled. Throughput was seen to drop for classification and remarking in some cases. In multiple instances, latency and jitter increased for classification and remarking. There are multiple ways of measuring jitter which were also discussed in the methodology development. It was also observed that some definitions which might seem better from a research perspective are not always available to measure or widely used in the industry. Based on the study it was concluded that service/network providers will have to take care while providing QoS to the customers in order avoid the scenarios discussed here.

December 13, 2004 Theses
Quartz Crystal Resonators and Oscillators for Frequency Control and Timing Applications - A Tutorial John Vig

This is a slide deck.
Chapter 1 (20 slides) provides an overview of clock synchronization applications.
Chapter 7 (11 slides) compares various types of oscillator.
Chapter 8 (33 slides) provides an overview of timekeeping.
The remainder of the 300 slides describe engineering details of quartz oscillators.

October 22, 2014 External Links
Radio Frequency Interference and Capacity Reduction in DSL Padmabala Venugopal (UNH-IOL), Michael J. Carter, Scott A. Valcourt

The issue of radio frequency interference in Digital Subscriber Line (DSL) networks is of particular concern in urban areas with many strong radio sources nearby. This paper investigates in detail the mechanisms underlying the capacity reduction due to the presence of radio frequency signals from Amplitude Modulated (AM) broadcast stations in an ADSL network. An ADSL system, channel, and radio frequency interference noise were simulated in MATLAB. The capacity reduction due to different Radio Frequency (RF) ingress conditions was studied. Spectral Spreading of the RF interferer, as suggested by Harris et al [1], is a primary cause of capacity reduction, but only at long loop lengths where the signal to Gaussian noise ratio is very low.

November 4, 2002 White Papers