Recursos VoIP - Enlaces

Fuente: Yale University
Formato: PDF

It has been increasingly popular to build VoiceoverIP (VoIP) applications based on Peer-to-Peer (P2P) networks in the Internet. However, many such VoIP applications freeride the network bandwidth of Internet Service Providers (ISPs). Thus their success may come at a cost to ISPs, especially those on the edge of the Internet. This paper explains the VoIP quality of Skype, a popular P2Pbased VoIP application. Specifically, using largescale end-to-end measurements, it first conducts a systematic analysis of Skype supernode network. This paper investigates the impacts of the access capacity constraint and the AS policy constraint on the VoIP quality of Skype.

Fuente: Avaya
Formato: PDF

The Avaya Converged Network Analyzer (CNA) provides services in a wide area-networking environment that are analogous to those provided by the global aircraft traffic control system to all of the airplanes in the air and the companies that are responsible for them. These services include - monitor, assess, and adapt. These three general service areas reflect a philosophy of how the network should support the business applications throughout a distributed IT infrastructure.

Fuente: Appia Communications
Formato: PDF

This white paper provides suggestions for achieving quality in Voice over IP (VoIP). VoIP operators need to recognize the limitations of the transport mechanism they use and take steps to overcome its weaknesses. If VoIP is implemented in a proper manner, the quality of calls is at least as good as the regular telephone system, and in many instances, even better.

Fuente: Global IP Sound
Formato: PDF

As voice over IP (VoIP) is emerging as a viable alternative to PSTN the performance of VoIP devices is expected to match that of traditional PSTN equipment. Global IP Sound selected five commercially available hands-free-capable IP phones to perform a series of subjective evaluations of the overall and specific aspects of quality related to acoustic echo cancellation. The goal was to evaluate the performance and quality of acoustic echo cancellation in currently available IP phones made by major vendors and to determine whether major brand VoIP phone could perform as well as typical PSTN speakerphones.

Fuente: Performance Technologies
Formato: PDF

This white paper will introduce important concepts surrounding jitter buffer management. First, it will discuss the reasons for a migration towards Voice over Internet Protocol (VoIP), and the challenges faced in implementing this service. Then, several industry-wide jitter buffer management techniques will be explained in detail. Finally, a review of the jitter buffer management solutions provided by Mapletree Networks will conclude the paper.

Fuente: Lucent Technologies
Formato: WORD

This paper describes the approach developed and used by Lucent, specifically AG Communication Systems' Voice Evaluation and Research Team, to evaluate and analyze voice quality on Voice over Packet systems.

Fuente: Sprint
Formato: PDF

Today's IP backbones are provisioned to provide excellent performance in terms of loss, delay and availability. However, performance degradation and service disruption are likely in the case of failure, such as fiber cuts, router crashes, etc. This paper investigates the occurrence of failures in Sprint's IP backbone and their potential impact on emerging services such as Voice-over-IP (VoIP).

Fuente: Institute of Electrical and Electronics Engineers
Formato: PDF

In the future, voice communication is expected to migrate from the Public Switched Telephone Network (PSTN) to the Internet. Because of the particular characteristics (low volume and burstiness) and stringent delay and loss requirements of voice traffic, it is important to separate voice traffic from other traffic in the network by providing it with a separate queue. In this study, we conduct a thorough assessment of voice delay in this context. We conclude that Priority Queuing is the most appropriate scheduling scheme for the handling of voice traffic, while preemption of non-voice packets is strongly recommended for sub-10 Mbit/s links. We also find that per-connection custom packetization is in most cases futile, i.e. one packet size allows a good compromise between an adequate end-to-end delay and an efficient bandwidth utilization for voice traffic.

Fuente: Polycom
Formato: PDF

The quality of an end user's experience is the true litmus test of a proper video/ voice deployment. Only by understanding both the application and network facilities for QoE can you absolutely ensure the highest quality user experience. This white paper discusses the breadth of AQoS within H.323 video/VoIP applications and highlights several AQoS solutions provided by Polycom's IPriority solution suite. Hopefully, this will provide you with a greater understanding of how important AQoS mechanisms are in the overall scheme of QoE.

Fuente: Avaya
Formato: PDF

Multimedia applications require stringent real time QoS guarantees. Successful deployment of such applications closely depends on the performance of the underlying data network. The characteristics and the QoS requirements of these applications are different from traditional data applications. This paper, the focus is on IP Telephony and it describes a framework for providing tools for IP Telephony readiness evaluation. This framework can be easily generalized to other multimedia applications. It presents a novel idea of relating voice quality metrics to the performance of data network devices.

Fuente: NetIQ
Formato: PDF

Vivinet Assessor employs the E-model, a powerful and repeatable way to assess whether a data network is ready to carry VoIP calls well. It's reports show the underlying network attributes that influence the calculation.

Fuente: Columbia University Department of Computer Science
Formato: PDF

We evaluate the availability of voice over IP (VoIP) service typically achieved in the current Internet. Service availability is examined using several metrics, including call success probability, overall packet loss probability, the proportion of time the network is suitable for VoIP service, and call abortion probability induced by network outages. Our major findings are: first, packet losses are not rare events, and it is generally worse on international paths. Secondly, network outages make up a non-negligible portion of packet losses. While most outages are short, some are extremely long and make up the majority time of all outages. This implies when a service becomes unavailable, the Mean Time To Restore (MTTR) can sometimes be very high. About one third of the outages happen in symmetry, and outages tend to occur at the edges rather than in the middle of the network. Thirdly, although research networks such as Internet2 has much lower delay and loss than the public Internet, the effect of network outages on both types of networks is almost the same.

Fuente: Lucent Technologies
Formato: PDF

Packet- based Voice over Internet Protocol (VoIP) services are becoming more widely deployed in service provider networks. Voice quality for these services often come into question, largely as a result of many factors including the compression algorithm, delay, jitter, suppression of silence, comfort noise generation, speech encoding, packet loss, and delay incurred from packetizing / depacketizing voice samples. This paper discusses how the 5E-XC Optical Interface Unit - Internet Protocol (OIU-IP) can address some of these concerns. The 5E-XC OIU-IP is a packet trunking peripheral for the 5ESS switch and addresses voice packetization, management of packet jitter, silence suppression, comfort noise generation, and echo cancellation.

Fuente: Cisco Systems
Formato: PDF

Cisco IOS Software offers a portfolio of QoS features that enable customer networks to address voice, video, and data application requirements, and are extensively deployed by numerous enterprises and Service Provider networks today. Cisco AutoQoS dramatically simplifies QoS deployment by automating Cisco IOS QoS features for voice traffic in a consistent fashion and leveraging the advanced functionality and intelligence of Cisco IOS Software.

Fuente: Avaya
Formato: PDF

The ExpertNet Lite Assessment Tool is a software application designed to perform an IP Network Readiness Assessment. To accomplish this, the tool gathers quality of service (QoS) information from an IP network. The data gathered is then analyzed by Avaya engineers to produce an ExpertNet Lite Assessment Tool report. It is designed to run for an extended period of time, typically five to seven days (note that five days is the recommended minimum), in order to see trends in network performance. These trends are often visible when the data is summarized graphically, and such graphs are typically included in an ExpertNet Lite Assessment Tool report.