Browsing by Author "Kordcal, A.R."

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Implementation of an adaptive buffering algorithm to improve QoS in VoIP
(2005) Nagesh, H.R.; Sekaran, K.C.; Kordcal, A.R.
The Internet has evolved into a worldwide communication infrastructure and it now provides various services including Voice over IP (VoIP) or Internet Telephony [7]. VoIP involves transmission of voice packets across the IP network known as IP telephony. Internet Protocol (IP) Telephony has many issues that have to be overcome before it can be considered a rival to the existing telephony infrastructure. One such issue is the Quality of service (QoS). The use of play-out buffering at the receiver helps to improve the quality of Voice over IP (VoIP). There exists a buffering algorithm, which uses a dynamic adaptive approach. In this algorithm the playout times of voice packets are calculated using adaptive estimation of the network delays. In contrast to previous solutions, weighting factor that controls the estimation process is dynamically adjusted according to the observed delay variations. This results in higher quality estimates of network delay. The contribution of this paper is to analyze, implement and incorporate one such adaptive buffering algorithm into the Session Initiation Protocol (SIP) through which one can achieve better delay/loss trade-off and thus better call quality.
Implementation of an adaptive buffering algorithm to improve QoS in VoIP
(2005) Nagesh, H.R.; Chandra Sekaran, K.C.; Kordcal, A.R.
The Internet has evolved into a worldwide communication infrastructure and it now provides various services including Voice over IP (VoIP) or Internet Telephony [7]. VoIP involves transmission of voice packets across the IP network known as IP telephony. Internet Protocol (IP) Telephony has many issues that have to be overcome before it can be considered a rival to the existing telephony infrastructure. One such issue is the Quality of service (QoS). The use of play-out buffering at the receiver helps to improve the quality of Voice over IP (VoIP). There exists a buffering algorithm, which uses a dynamic adaptive approach. In this algorithm the playout times of voice packets are calculated using adaptive estimation of the network delays. In contrast to previous solutions, weighting factor that controls the estimation process is dynamically adjusted according to the observed delay variations. This results in higher quality estimates of network delay. The contribution of this paper is to analyze, implement and incorporate one such adaptive buffering algorithm into the Session Initiation Protocol (SIP) through which one can achieve better delay/loss trade-off and thus better call quality.
Proactive model for mitigating Internet denial-of-service attacks
(2007) Nagesh, H.R.; Chandra, Sekaran, K.; Kordcal, A.R.
Denial-of-Service is one of the most frequent, costly and rapidly growing attacks on the Internet. In a denial of service attack, a malicious user exploits the connectivity of the Internet to cripple the services offered by a victim site, often simply by flooding a victim with many requests. In this paper we have compared the three main architectures already proposed for mitigating the DoS attacks. The comparison is with respect to incremental deployment, traffic analysis, and the attacks on the infrastructure itself. Finally, we combine the strengths of the different proposals to propose a new model for denial of service. Our model uses the concept of active networks to mitigate DoS attacks. � 2007 IEEE.
Proactive model for mitigating Internet denial-of-service attacks
(2007) Nagesh, H.R.; Chandra Sekaran, K.; Kordcal, A.R.
Denial-of-Service is one of the most frequent, costly and rapidly growing attacks on the Internet. In a denial of service attack, a malicious user exploits the connectivity of the Internet to cripple the services offered by a victim site, often simply by flooding a victim with many requests. In this paper we have compared the three main architectures already proposed for mitigating the DoS attacks. The comparison is with respect to incremental deployment, traffic analysis, and the attacks on the infrastructure itself. Finally, we combine the strengths of the different proposals to propose a new model for denial of service. Our model uses the concept of active networks to mitigate DoS attacks. Â© 2007 IEEE.