86 research outputs found
Signalling in voice over IP Networks
Voice signalling protocols have evolved, keeping with the prevalent move from circuit to packet switched networks. Standardization bodies have provided solutions for carrying voice traffic over packet networks while the main manufacturers are already providing products in workgroup, enterprise, or operator portfolio. This trend will accrue in next years due to the evolution of UMTS mobile networks to an âall-IPâ environment. In this paper we present the various architectures that are proposed for signalling in VoIP, mainly: H.323, SIP and MGCP. We also include a brief summary about signalling in classical telephone networks and, at the end, we give some ideas about the proposed âall-IPâ architectures in UMTS 3G mobile networks.Publicad
IPv6 Network Mobility
Network Authentication, Authorization, and Accounting has
been used since before the days of the Internet as we know it
today. Authentication asks the question, âWho or what are
you?â Authorization asks, âWhat are you allowed to do?â And fi nally,
accounting wants to know, âWhat did you do?â These fundamental
security building blocks are being used in expanded ways today. The
fi rst part of this two-part series focused on the overall concepts of
AAA, the elements involved in AAA communications, and highlevel
approaches to achieving specifi c AAA goals. It was published in
IPJ Volume 10, No. 1[0]. This second part of the series discusses the
protocols involved, specifi c applications of AAA, and considerations
for the future of AAA
Multicast traffic aggregation in MPLS-based VPN networks
This article gives an overview of the current
practical approaches under study for a scalable implementation of multicast in layer 2 and 3 VPNs over an IP-MPLS multiservice network. These proposals are based on a well-known technique: the aggregation of traffic into shared
trees to manage the forwarding state vs. bandwidth saving trade-off. This sort of traffic engineering mechanism requires methods to estimate the resources needed to set up a multicast shared tree for a set of VPNs. The methodology proposed in this article consists of studying the effect of aggregation obtained by random shared
tree allocation on a reference model of a representative network scenario.Publicad
Scalable QoS-aware Mobility for Future Mobile Operators
Telecom operators and Internet service providers
are heading for a new shift in communications
paradigms. The forthcoming convergence
of cellular and wireless data networks is often
manifested in an âall IP approachâ in which all
communications are based on an end-to-end IP
protocol framework. The approach to network
design becomes user and service-centered, so
that continuous reachability of mobile users and
sustained communication capabilities are default
requirements for a prospective architecture. In
this article, we describe a network architecture
which is able to provide seamless communication
mobility, triggered either by the user or by the
network, across multiple technologies. The architecture
allows for media independent handovers
and supports optimized mobility and resource
management functions. The main focus of the
article is on major technical highlights of mobility
and quality-of-service (QoS) management subsystems
for converged networks.Publicad
Protocolos de señalización para el transporte de voz sobre redes IP
En los Ășltimos años, los protocolos de señalizaciĂłn para el servicio de transmisiĂłn de voz han experimentado una fuerte evoluciĂłn junto con la tendencia a trasportar dicho trĂĄfico desde las redes de conmutaciĂłn de circuitos hacia las redes de conmutaciĂłn de paquetes. Esta tendencia queda reflejada con la fuerte evoluciĂłn de estĂĄndares en este ĂĄmbito y la apariciĂłn de productos en el mercado que cubren las necesidades de operadores, grandes empresas y PYMES [1] [2] [3]. Esta tendencia se verĂĄ incrementada durante los prĂłximos 5 años debido a la evoluciĂłn de las redes mĂłviles basadas en tecnologĂa UMTS hacia entornos âAll-IPâ. En este articulo se presentan las diferentes arquitecturas que estĂĄn siendo propuestas para soportar la señalizaciĂłn de sistemas VoIP, debidas principalmente a los estĂĄndares H.323, SIP y MGCP, junto con una breve resumen de los mecanismos de señalizaciĂłn en redes telefĂłnicas clĂĄsicas (SS7) y algunas ideas sobre la evoluciĂłn hacia âALL-IPâ en redes mĂłviles de 3G basadas en UMTS.Publicad
Hierarchy and Competition in CSCW applications: Model and case study
CSCW applications need to adapt themselves to the functional and organizational structures of people that use them. However they do not usually support division in groups with a certain hierarchical structure among them. In this paper, we propose and study a theoretical model of groupware appliations that reflects those hierarchical interactions. The proposed model is also intended to evaluate the effects in performance derived from competitive and collaborative relationships among the components of a hierarchy of groups. In order to demonstrate the above ideas, a groupware game, called Alymod, was designed and implemented using a modified version of a well-known CSCW Toolkit, namely Groupkit. Groupkit was modified in order to support group interactions in the same CSCW application. In Alymod, participants compete or collaborate within a hierarchical structure to achieve a common goal (completing gaps in a text, finishing numerical series, resolving University course examinations, etc.).Publicad
IMS signalling for multiparty services based on network level multicast
3rd EURO-NGI Conference on Next Generation Internet Networks. Norwegian University of Science and Technology, Trondheim, Norway, 21-23 may 2007.The standardization process of the UMTS technology has led to the development of the IP Multimedia Subsystem (IMS). IMS provides a framework that supports the negotiation of the next generation multimedia services with QoS requirements that are envisioned for 3G networks. But even though many of these services involve the participation of multiple users in a multiparty arrangement, the delivery technology at network level is still unicast based. This approach is not optimum, in terms of transmission efficiency. In this paper, a new approach is presented proposing to use a network level multicast delivery technology for the multiparty services that are signalled through IMS. The main advantages and drawbacks related with this new approach are analyzed in the article. Finally, as a starting point in the development of the presented solution, a new SIP signalling dialogue is proposed allowing the negotiation of a generic multiparty service, and supporting at the same time the configuration of the corresponding network level multicast delivery service with QoS requirements that will be used in the user plane.Publicad
Analysis of the effect of mobile terminal speed on WLAN/3G vertical handovers
Proceedings of IEEE Global Telecommunications Conference, GLOBECOM '06, San Francisco, California, 27 november - 1 december, 2006.WLAN hot-spots are becoming widely spread. This, combined with the availability of new multi-mode terminals integrating heterogeneous technologies, opens new business opportunities for mobile operators. Scenarios in which 3G coverage is complemented by WLAN deployments are becoming available. Thus, true all-IP based networks are ready to offer a new variety
of services across heterogeneous access. However, to achieve this, some aspects still need to be analyzed. In particular, the effect of the terminal speed on the detection and selection process of the preferred access network is not yet well understood. In
fact, efficiency of vertical handovers depends on the appropriate configuration of mobile devices. In this paper we present a
simulation study of handover performance between 3G and WLAN access networks showing the impact of mobile usersâ speed. The mobile devices are based on the IEEE 802.21 cross
layer architecture and use WLAN signal level thresholds as handover criteria. A novel algorithm to dynamically adjust terminalsâ configuration is presented.Publicad
Mobile Networking
We point out the different performance problems that need to be addressed when considering mobility in IP networks. We also define the reference architecture and present a framework to classify the different solutions for mobility management in IP networks. The performance of the major candidate micro-mobility solutions is evaluated for both real-time (UDP) and data (TCP) traffic through simulation and by means of an analytical model. Using these models we compare the performance of different mobility management schemes for different data and real-time services and the network resources that are needed for it. We point out the problems of TCP in wireless environments and review some proposed enhancements to TCP that aim at improving TCP performance. We make a detailed study of how some of micro-mobility protocols namely Cellular IP, Hawaii and Hierarchical Mobile IP affect the behavior of TCP and their interaction with the MAC layer. We investigate the impact of handoffs on TCP by means of simulation traces that show the evolution of segments and acknowledgments during handoffs.Publicad
Design and Experimental Evaluation of a Route Optimisation Solution for NEMO
An important requirement for Internet protocol (IP)
networks to achieve the aim of ubiquitous connectivity is network
mobility (NEMO). With NEMO support we can provide Internet
access from mobile platforms, such as public transportation vehicles,
to normal nodes that do not need to implement any special
mobility protocol. The NEMO basic support protocol has been
proposed in the IETF as a first solution to this problem, but this
solution has severe performance limitations. This paper presents
MIRON: Mobile IPv6 route optimization for NEMO, an approach
to the problem of NEMO support that overcomes the limitations
of the basic solution by combining two different modes of operation:
a Proxy-MR and an address delegation with built-in routing
mechanisms. This paper describes the design and rationale of the
solution, with an experimental validation and performance evaluation
based on an implementation.Publicad
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