Recursos VoIP - Enlaces

Fuente: Allied Telesyn
Formato: PDF

With the trends towards IP telephony and converged applications becoming a reality, there is now a greater need to incorporate Quality of Service (QoS) in the network infrastructure. There are many ways to implement QoS using techniques such as IEEE 802.1p/Q. DiffServ/TOS, RSVP, and MPLS. This paper explains how QoS can ensure that delay-sensitive applications are prioritized and helps in making the network more efficient and reliable for all applications.

Fuente: Siemens
Formato: PDF

Voice over Packet technology is designed to break down the barrier between traditional public switched telephone networks (PSTN) and data (ATM or IP) networks. The concept of transporting voice across packet backbones is an important building block of the so-called “Next Generation Network” infrastructure or NGN for short. This white paper compares the attainable QoS of Voice over IP (VoIP) and Voice over Asynchronous Transfer Mode (VoATM) packet technologies as investigated by various carriers and equipment manufacturers today.

Fuente: Cisco Systems
Formato: PDF

Quality of Service (QoS) refers to the capability of a network to provide better service to selected network traffic over various technologies, including Frame Relay, Asynchronous Transfer Mode (ATM), Ethernet and 802.1 networks, SONET, and IP-routed networks that may use any or all of these underlying technologies. The primary goal of QoS is to provide priority including dedicated bandwidth, controlled jitter and latency (required by some real-time and interactive traffic), and improved loss characteristics. Also important is making sure that providing priority for one or more flows does not make other flows fail. QoS technologies provide the elemental building blocks that will be used for future business applications in campus, WAN and service provider networks.

Fuente: Empirix
Formato: PDF

This paper has examined the devices involved in VoIP transmissions, the conditions that could affect their performance and how to create a test environment that is comprehensive enough to reliably assess a VoIP system’s performance under stress. In addition, we have discussed how that performance should be measured, using standards-based methodologies that recognize that the actual perception of users cannot be left out if a true evaluation is to be made. There are many methods currently under discussion by VoIP equipment and service providers for improving quality of service and even providing customers with QOS guarantees. If implemented, these methods should help in improving how conversations in the VoIP environment sound, adding some consistency to quality performance. This is necessary before general business acceptance of outside enterprise intranets will occur. In the final analysis, the success of the industry hinges on the positive perception of human beings using telephones.

Fuente: Brix Networks
Formato: PDF

This paper provides a blueprint for a carrier-based network monitoring strategy designed to highlight and address performance issues and lower network total cost of ownership. It addresses the most important questions, including: What portions of the network, if monitored, will yield the biggest payback?; What measurements are most predictive of network health and must be collected?; How to test, including the type of tests to run and testing frequency.

Fuente: Indiana University
Formato: Word

Most current Voice/Video over IP (VoIP) systems are either highly centralized or dependent on IP multicast. This paper proposes the Global Multimedia Collaboration System as a scalable, integrated and service-oriented VoIP conferencing system, based on a SOAP-based collaboration framework and advanced messaging oriented middleware. This system can provide media and session services to heterogeneous endpoints including H.323, SIP, Access Grid, and RealPlayer as well as accommodating diverse clients such as cellular phones. The authors suggest that the approach opens up new opportunities for extending classic VoIP systems by using these new technologies designed for scalable Internet based service-oriented computing.

Fuente: Spirent
Formato: PDF

VoIP applications require service quality management (SQM), which can be defined as the ability to monitor and manage the network to ensure a defined service level, regardless of the technology, service, protocol, or vendor. Employing the appropriate tools will enable all aspects of SQM for VoIP. This paper identifies the proper placement of these tools to provide complete SQM for various VoIP applications.

Fuente: Detecon
Formato: PDF

As wireless markets mature, a common expectation is a guaranteed quality of service, especially for the high end of the market. To that extent, there are an impressive number of specifications, publications, or papers that deal with the subject of measuring the perceived quality of service in Wireless Data Networks. However, there's little or no practical information on Service Quality Management (SQM). With the advent of 2.5G and 3G technologies and the promise of innovative IP-enabled services, the wireless landscape is beginning to change. In order to support seamless interoperability with the Internet and the delivery of a large variety of data services, mobile networks are migrating to packet-switched architectures.

Fuente: Indiana University
Formato: PDF

The availability of increasing network bandwidth and computing power provides new opportunities for videoconferencing systems over Internet. Multimedia capable devices with broadband Internet connections are spreading rapidly. Even cell phones will have broadband internet access in the near future. This requires universally accessible and scalable videoconferencing systems that can deliver thousands of concurrent audio and video streams. However, developing videoconferencing systems over Internet is a challenging task, since audio and video communications require high bandwidth and low latency. It is believed that with the advancements in computing power and network bandwidth, more flexible and service oriented systems should be developed.

Fuente: Indiana University
Formato: PDF

The availability of increasing network bandwidth and the computing power provides new opportunities for videoconferencing systems over Internet. On one hand, broadband Internet connections are spreading rapidly. Even cell phones will have broadband internet access in the near future with the implementations of 3G standards. However, developing videoconferencing systems over Internet is a challenging task, since audio and video communications require high bandwidth and low latency. In addition, the processing of audio and video streams is computing intensive. Therefore, it is particularly difficult to develop scalable systems that support high number of users with various capabilities.

Fuente: University of Twente
Formato: PDF

Next-generation communication services will be offered over distributed information and communication infrastructures consisting of a multitude of administrative domains, owned by different parties. This raises the problem for service providers to provide satisfactory levels of end-to-end Quality of Service (QoS), as experienced by the paying end user, in a cost-effective manner. Motivated by this, the authors consider the problem of end-to-end QoS provisioning for TCP-based applications that cross multiple network domains. To this end, the authors construct an analytical model that provides a so-called SLA calculus, i.e. a mapping between per-domain network QoS parameters defined in the involved Service Level Agreements (SLAs) and end-to-end QoS metrics like response times and file download times that determine the QoS perceived by the end users.

Fuente: Brooktrout Technology
Formato: PDF

The absence of solutions ensuring Quality of Service (QoS) has been a deterrent to the widespread adoption of Voice over IP (VoIP). Potential users often think that speech quality will not be as good as what they are accustomed to - the familiar public switched telephone network (PSTN). What users and their organizations expect from VoIP is essentially PSTN quality and objective verification that they are receiving it. VoIP service providers must meet these expectations if they want to profit from faster market penetration. This article describes a framework for solutions which improve absolute voice quality and which enable objective quality measurements - metrics that can easily be incorporated into Service Level Agreements (SLAs). With these solutions in hand, the reluctance of potential users can begin to evaporate, and the adoption of VoIP will stand poised for a period of explosive growth.

Fuente: Lucent Technologies
Formato: WORD

This paper provides a high-level overview of voice quality and testing methods that Lucent uses to measure the voice quality of the iMerge Voice over IP (VOIP) system. This document also covers some LAN and WAN design guidelines.

Fuente: Ericsson
Formato: WORD

Next generation networks (NGN's) handle a wide variety of traffic types (both real-time and non-real-time) that compete for resources. As a result, there is a lot of interest in modeling Quality of Service (QoS) in NGN's, both wireline and wireless. QoS in these networks depends on a number of factors such as traffic utilization level, source traffic profile, and scheduling and shaping mechanisms. This paper investigates some of these issues by making use of OPNET simulations of both General Packet Radio Service (GPRS) and next generation wireline networks.

Fuente: Massachusetts Institute of Technology
Formato: PDF

In this paper we focus on RSVP-based resource reservations in a heterogeneous environment which includes ATM networks. We describe a method for establishing shortcuts for the data flow through an ATM network which avoids the performance penalty associated with layer 3 processing in the classical IP over ATM approach. For the guaranteed and controlled-load types of services we show how to map the RSVP flow characteristics to ATM call parameters, and thus enable end-to-end quality of service. Finally, we discuss some concerns which have been raised regarding the use of RSVP in establishing shortcuts.