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        1 - Evaluation of SIP signaling implementation using QoS parameters
        mojtaba jahanbakhsh azharivs azharivs maryam homayooni Ahmad akbari
        Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 More
        Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 !mso]> st1:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal" mso-tstyle-rowband-size:0 mso-tstyle-colband-size:0 mso-style-noshow:yes mso-style-priority:99 mso-style-qformat:yes mso-style-parent:"" mso-padding-alt:0cm 5.4pt 0cm 5.4pt mso-para-margin:0cm mso-para-margin-bottom:.0001pt mso-pagination:widow-orphan font-size:11.0pt font-family:"Calibri","sans-serif" mso-ascii-font-family:Calibri mso-ascii-theme-font:minor-latin mso-fareast-font-family:"Times New Roman" mso-fareast-theme-font:minor-fareast mso-hansi-font-family:Calibri mso-hansi-theme-font:minor-latin mso-bidi-font-family:Arial mso-bidi-theme-font:minor-bidi} Abstract The variety of services on IP networks and the need for network technology convergence have resulted in many access networks to adopt the IP technology. The Session Initiation Protocol (SIP) is an end to end application level protocol for establishing, terminating and modifying sessions and has experienced widespread use in IP networks due to its distinguished features such as being text based, independence from the underlying network, and more importantly supporting various types of mobility. In fact these features have lead SIP to be used as the core signaling protocol in the IP Multimedia Subsystem, which is the control plane proposed for next generation networks by the 3GPP community. Nevertheless, the performance of SIP servers when used by the millions of users of the next generation networks is not well established. In this paper we evaluate the performance of SIP servers using a test bed developed at the Iran University of Science & Technology. We consider eight different configurations for SIP server and also study the effect of using TCP and UDP as the transport protocol for SIP packets. We measure several parameters including call setup delay, call failure rate and SIP server throughput. Our results suggest that using SIP in large networks require using special techniques for balancing the load of SIP servers as well as mitigating temporary overloads.  Manuscript profile
      • Open Access Article

        2 - Multicast computer network routing using genetic algorithm and ant colony
        Mohammad Pourmahmood Aghababa
        Due to the growth and development of computer networks, the importance of the routing topic has been increased. The importance of the use of multicast networks is not negligible nowadays. Many of multimedia programs need to use a communication link to send a packet from More
        Due to the growth and development of computer networks, the importance of the routing topic has been increased. The importance of the use of multicast networks is not negligible nowadays. Many of multimedia programs need to use a communication link to send a packet from a sender to several receivers. To support such programs, there is a need to make an optimal multicast tree to indicate the optimal routes from the sending source to the corresponding sinks.  Providing an optimal tree for routing is a complicated problem. In this paper, we are looking forward a method for routing of multicast networks with considering some parameters such as the cost and delay. Also, this paper has emphasized the issue that every parameter in routing problem has different value for different packets. And in accordance to these parameters optimal routing multicast trees are proposed. To gain this end, the genetic algorithm and ant colony optimization approaches are adopted. The simulation results show that the presented algorithms are able to produce optimal multicast trees subject to the packets. Manuscript profile
      • Open Access Article

        3 - Routing of Multipartite Computer Networks Using Ant Genetic Algorithm
        Mohammad Pourmahmood Aghababa amin bahadorani baghbaderani
        With the growth and development of computer networks, the importance of routing has become a thing of the past. The importance of using multi-sectoral networks cannot be ignored today. Many multimedia applications require sending a packet from one source to multiple des More
        With the growth and development of computer networks, the importance of routing has become a thing of the past. The importance of using multi-sectoral networks cannot be ignored today. Many multimedia applications require sending a packet from one source to multiple destinations over a communication network. To support such programs, you need to create an optimal multipart tree , Which indicates the optimal routes to reach from one sender source to several desired destinations. Manuscript profile
      • Open Access Article

        4 - A Model for Mobile Code Computing Paradigms in Computer Networks
        Hojatallah Hamidi Maryam Parvini
        This paper presents a reliable model for mobile codes in distributed networks, which represents reliable mobile agent execution. The model ensures non-blocking mobile agent execution and forces the once property without relying on correct fault detection. A mobile agent More
        This paper presents a reliable model for mobile codes in distributed networks, which represents reliable mobile agent execution. The model ensures non-blocking mobile agent execution and forces the once property without relying on correct fault detection. A mobile agent execution is blocking if a fault of agent prevents the agent from continuing in its execution. The once problem is related to non-blocking in the sense that solutions to the latter may lead to multiple executions of the mobile agent. A solution to reliable mobile agent execution needs to ensure both the non-blocking and once properties. The analytical results show new theoretical perceptions into the statistical behaviors of mobile agents and provide useful tools for executing mobile agents in networks. The results show that agents' behavior is influenced by places' characteristics and the agents' behavior can be managed to network. In this paper, we analyzed the average time consuming of mobile agents between two places. The approach, Fault-Tolerant approach for mobile codes offers a user-transparent fault tolerance which can be selected by the user for every single application given to the environment. Thereby, the user can decide for every application weather it has to be treated fault-tolerant or not. We proposed a reliable execution model of mobile codes and analyzed the life expectancy, including the average time consuming of mobile agents between two places, the average number of places agents will visit, and the agents' life expectancy. Manuscript profile
      • Open Access Article

        5 - On the Stability of Primal-Dual Congestion Control Algorithm in the Presence of Exogenous Disturbances
        A. moarefianpour V. johari majd
        In this paper, we consider the effects of exogenous disturbances on the closed-loop system of the congestion control problem in a network with general structure. This investigation is important since many of data flows in internet network are considered as unmodeled flo More
        In this paper, we consider the effects of exogenous disturbances on the closed-loop system of the congestion control problem in a network with general structure. This investigation is important since many of data flows in internet network are considered as unmodeled flows. In contrast to previous works, we suppose that both senders and links in the network have dynamics. Each sender updates its sending rate to minimize its own cost function. The network is modeled based on fluid flow approximation with nonlinear dynamics for the links. In this research, we first derive the conditions for the existence of the system equilibrium point taking into account the constraint sets of the problem. Then, we prove input-to-state stability (ISS) of the closed-loop system for the congestion control problem with input and output disturbances in the network links. We further show that the obtain results are valid even when the routing matrix of the network varies. Finally, we verify the theoretical results by simulation on two different multi-link networks. Manuscript profile