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In IP multimedia subsystem (IMS), in order to have a multimedia service first a session should be established. The signaling part is done by the SIP protocol-the most important protocol used in IMS network. Excessive signaling during the session setup mechanism leads to an undesirable delay in session establishment and also the final response of the other subscriber. This matter is considered important...
The goal of this work is to characterize scientific data transfers and to determine the suitability of dynamic virtual circuit service for these transfers instead of the currently used IP-routed service. Specifically, logs collected by servers executing a commonly used scientific data transfer application, GridFTP, are obtained from three US super-computing/scientific research centers, NERSC, SLAC,...
We study the effect of TCP synchronization on Optical Burst Switched (OBS) networks and its impact on capacity dimensioning. The synchronization of TCP flows appears when a burst with segments from different TCP flows is discarded, making that all TCP flows reduce their transmission rate at the same time, leading to inefficient bandwidth sharing. This paper analyzes the bandwidth capacity that needs...
This paper presents the results of the performance evaluation concerning 3G/3GPP IP Multimedia Subsystem (IMS) applications deployed in a wireless multi-hop network controlled by the Delay-Aware Network Utility Maximization System (DANUMS). The main purpose of the DANUM system is simultaneous service of files and multimedia streams, i.e., types of traffic of different delay requirements. DANUMS combines...
Random Early Detection (RED) algorithm, a framework of active queue management (AQM), has been proposed in order to improve the performance of congestion routers due to the increased use of Internet. But, the basic problem of a lag between congestion's occurrence and its remedy remained. To overcome this problem of RED, Explicit Congestion Notification (ECN) proposed by the IETF that allows end-to-end...
Over the last decade, VoIP has had a fast growth particularly in Small Office Home Office environments overloading the wireless accesses in the last mile. Network Coding schemes have advantageous features for throughput performance but VoIP is a delay critical service requiring fast routing algorithms. In this paper, we design, implement and measure experimental values for a network coding based VoIP...
Transmission of voice over packet-based protocol has recently gained momentum. To this effect, Voice over Internet Protocol (VoIP) implementations on current and future versions of the Internet Protocols networks is becoming a convenient and inexpensive technology. This is the technology that is replacing traditional public switched telephone networks (PSTN). However, like any other such technology,...
In this paper, the performance of IPv4 and IPv6 are compared for both Client-Server and Peer-Peer networks. For both networks, IPv4 produced higher bandwidth for TCP protocol. For UDP, IPv4 and IPv6 showed insignificant bandwidth differences except for packet size of 384 bytes where IPv4 had better performance in client-server environment.
The dominant IP traffic is moving from Web to peer-to-peer (P2P) these days. As a result, elephant flows consume bandwidth and unfairness in resources allocation occurs. The main packet-scheduling mechanism currently employed is first-in first-out (FIFO) where the available bandwidth of short flows is limited by elephant flows. Least attained service (LAS), which decides transfer priority of packets...
The paper focuses on implementation of association pattern between the network performances and the general network faults. We use network simulation tool, OPNET, to accomplish network simulations of different network faults and different situations based on VoIP. Network performance parameters such as end-to-end delay, jitter, traffic dropped, queuing delay, link throughout, link utilization are...
With the rapid increasing of the same destination address traffic, traditional forwarding equivalence class (FEC) can not process these traffic efficiently. After elaborating the drawbacks of single FEC, we propose a variable FEC (VFEC) algorithm and evaluate the algorithm using ns2 simulation. VFEC obtains alternative paths and forwards these traffic to multiple available paths. From the thorough...
With today's widespread deployment of wireless technologies, it is often the case that a single communication device can select from a variety of access networks. At the same time, there is an ongoing trend towards integration of multiple network interfaces into end-hosts, such as cell phones with HSDPA, Bluetooth and WLAN. By using multiple Internet connections concurrently, network applications...
Session Initiation Protocol (SIP) is adopted as the main signaling protocol for the IP Multimedia Subsystem (IMS). Large deployment of SIP servers in Next Generation Networks (NGN) requires studying the behavior and performance of SIP servers under both normal and overload conditions, which may happen in such networks with a vast number of users. In this paper a measurement-based study is performed...
We evaluate a video server system that performs streaming transmissions of consumer generated video (CGV) files. The CGV files are placed in iSCSI (i.e., SCSI over TCP/IP) storages at each individual's home, and the iSCSI storages are connected to one video server on demand. Since iSCSI uses the TCP protocol, the network delay greatly affects the iSCSI throughput. Although iSCSI storages have different...
The last decade has seen explosive growth in the development of mobile applications. This has increased the demand on the wireless communication services. The capability to achieve wireless access anywhere, anytime, and anyplace has become common expectation as it provides significant flexibility and freedom in mobility. But to achieve global mobility in heterogeneous networks for any mobile device...
Wireless mesh networks (WMNs) are emerging as a promising technology for backhauling data traffic from wireless access networks to the wired Internet. Such networks are expected to support various types of applications with different quality of service (QoS) requirements. In this paper, we provide a complete cross-layer solution for WMNs together with its OPNET simulation architecture that comprises...
The rapid development of next generation network (NGN), communication technology and programming router in the last few years have given rise to a strong research interest in concurrent multipath (CMP) technology. Based on the analysis of flow relation and forward granularity, a novel network layer CMP forward algorithm, CCRF (crosslayer CMP random forward), is proposed. CCRF can classify different...
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