Connection Setup Research Articles

Improved EDF-based management of the setup of connections in opaque and transparent optical networks

The need to support the diverse quality-of-service (QoS) requirements of the ever-emerging Internet applications is a major challenge for optical network operators. This paper tackles such a challenge through the definition of a QoS-aware optical connection setup management scheme. The proposed scheme utilizes the Earliest Deadline First (EDF) queueing discipline to schedule the setup of optical connections that cannot be established due to lack of optical resources. The EDF-based approach aims at minimizing blocking probability while realizing QoS differentiation. Blocking probability reduction is realized through the insertion of blocked connection requests into a queue giving them thus a second chance with respect to network access. QoS differentiation on the other hand is achieved as follows. The blocked connection requests are ranked in the EDF queue according to their connection setup requirements, which are viewed as deadlines during connection setup. In this way, pending connection requests having shorter setup time requirements are guaranteed to experience better QoS compared to the ones having longer setup time requirements. The performance of the EDF-based strategy is analyzed through extensive simulations in the context of both opaque and transparent NSFNET network topologies. The reported results show that the proposed strategy yields remarkable reduction in terms of blocking probability while effecting QoS differentiation.

Toward Wireless Backhaul Using Circuit Emulation Over Optical Packet-Switched Metro WDM Ring Network

Optical WDM metro-ring networks have been considered to be promising solutions for wireless backhaul. In this paper, we propose an integrated traffic control scheme (ITCS), which facilitates circuit emulation service (CES) for wireless backhaul over a previously proposed experimental optical packet-switched WDM metro-ring network, HOPSMAN. The ITCS seamlessly integrates variable-bit-rate (VBR) CES wireless with connection-less best-effort data, satisfying stringent QoS requirements and retaining maximal network throughput. The ITCS ensures efficient setup of CES connections by employing a simple mean-rate-based distributed admission control followed by a novel slot-marking reservation. The total connection setup delay is comprised of the setup queueing delay and slot-marking delay. While the slot-marking delay is nearly a ring time, the mean setup queueing delay is formally computed through an accurate approximation based on an M/G/m queueing analysis. We show simulation results to demonstrate that the ITCS accommodates remarkably high CES traffic loads while satisfying a wide range of delay requirements for wireless backhaul. Taking the background best-effort traffic into account, ITCS achieves exceedingly low delay, jitter, and delay bound for CES under various traffic loads and burstiness.

Distributed multi-hop reservation protocol for wireless personal area Ultra-Wideband networks

Ultra-wideband (UWB) technology is a promising technology for multimedia applications in wireless personal area networks (WPANs) that supports very high data rates with lower power transmission for short range communication. The limitation of coverage radius of UWB network necessitates for multihop transmissions. Unfortunately, as the number of hops increases, the quality of service (QoS) degrades rapidly in multihop network. The main goal of this research is to develop and enhance multihop transmission that ensures QoS of real time traffic through the proposed distributed multihop reservation (DMR) scheme. The DMR scheme consists of two modules; distributed multihop reservation protocol (DMRP) and path selection. DMRP incorporates resource reservation, routing and connection setup that are extended on the existing WiMedia Media Access Control protocol (MAC). On the other hand, the path selection determines the optimal path that makes up the multihop route. The path selection selects nodes based on the highest Signal to Interference and Noise Ratio (SINR). The performance of DMR scheme has been verified based on the performance of the video traffic transmission. The main metrics of QoS are measured in terms of Peak Signal- to- Noise ratio (PSNR), End-to-End (E2E) delay, and throughput. The results show that DMRP compared to Multiple Resources Reservation Scheme (MRRS) in six (6) hops transmission has enhanced the average PSNR by 16.5%, reduced the average E2E delay by 14.9% and has increased the throughput by 11.1%. The DMR scheme which is the inclusion of path selection in DMRP has been compared to Link Quality Multihop Relay (LQMR). DMR scheme has improved the video quality transmission by 17.5%, reduced the average E2E delay by 18.6% and enhanced the average throughput by 20.3%. The QoS of six (6) hops transmission employing DMR scheme is almost sustained compared to two hops transmission with the QoS experiencing only slight degradation of about 2.0%. This is a considerable achievement as it is well known that as the number of hops increases the QoS in multihop transmission degrades very rapidly. Thus DMR scheme has shown to significantly improve the performance of real time traffic on UWB multihop network. In general, DMR can be applied to any WPAN network that exploit multihop transmission.

Web performance bottlenecks in broadband access networks

We present the first large-scale analysis of Web performance bottlenecks as measured from broadband access networks, using data collected from extensive home router deployments. We analyze the limits of throughput on improving Web performance and identify the contribution of critical factors such as DNS lookups and TCP connection establishment to Web page load times. We find that, as broadband speeds continue to increase, other factors such as TCP connection setup time, server response time, and network latency are often dominant performance bottlenecks. Thus, realizing a "faster Web" requires not only higher download throughput, but also optimizations to reduce both client and server-side latency.

Path Protection with Hierarchical PCE in GMPLS-Based Multi-domain WSONs

This paper proposes an effective mechanism for establishing protected connections in GMPLS-based multi-domain WSONs employing the Hierarchical PCE architecture. The proposed scheme exploits communication among parent PCE and child PCEs for computing a pair of link-disjoint paths satisfying the wavelength continuity constraint that are allowed to traverse the same domain sequence or partially overlapped domain sequences. The proposed scheme is evaluated by means of simulations in terms of achieved blocking probability, connection setup time, and control plane overhead. Simulation results show that the proposed scheme overcomes the state of the art in terms of blocking probability and setup time with a slightly increased control plane overhead.

Impact of IEEE 802.16 ARQ mechanism on the performance of TCP-NewReno

IEEE 802.16 supports Automatic Repeat request ARQ at the link layer to provide reliable service. ARQ retries sending a data-unit until the transmission is successful or maximum retries has reached. For applications which require reliability, the dropped data-unit is to be recovered at the transport layer level by TCP, which operates over ARQ. While TCP's retransmission policy continuously adjusts retransmission-timeout RTO based on the current round-trip-time, ARQ uses the static parameters set during the connection set-up procedure. This paper uses simulations to study the impact of one such static ARQ parameter, ARQ_BLOCK_LIFETIME on the performance of TCP-NewReno over IEEE 802.16 for Best Effort BE up-link traffic. Simulations were carried out using modified version of NS-2 WiMAX Simulator Release 2.6. The performance metric considered is TCP goodput. The results from the simulations show that the optimal value for ARQ_BLOCK_LIFETIME is influenced by Round Trip Time RTT, the network-load, and error-rate.

Spectral resource defragmentation based on PCE in flexible bandwidth optical networks

The granularity of the flexible bandwidth optical network is the spectral slots, which is much smaller than that of the wavelength switch optical network. For the dynamic clients' connections setup and tear down processes, it will give rise to fragmentation of spectral resources. It is the decline in the probability of finding suficient contiguous spectrum for new connections that result in the fragmentation of spectral resource. To be more specific, these spectra may be unavailable and waste. In this case, the severe waste of the spectrum will lead to low efficiency in spectral utilization and will not adapt to large capacity requirements of transmission in the future. Because path computation element (PCE) framework has the characteristics of the central disposal and deployment of the spectrum resource, we construct the spectral resource allocation scenario based on PCE framework in the flexible bandwidth optical network to use spectrum resource effectively. Based on the principle of the generation of the fragmentation, we put forward a spectrum resource defragmentation algorithm to consolidate the available spectrum for clients' connections. The simulation results indicate that this algorithm is able to reduce fragmentation of network, improve the continuity of spectral resource, reduce the blocking rate of services in the network and improve the spectral efficiency significantly.

Roadside Inventions: Making Time and Money Work at a Road Construction Site in Mozambique☆

Based on ethnographic fieldwork at a road construction site in southern Mozambique, this article explores the peculiar inverse process through which the road project acquired valuable meaning for young Mozambican workers hired by a Chinese construction consortium to rehabilitate the north–south N1 highway. Without viable alternatives, the Mozambican workers were often compelled to accept the intolerable working conditions that the Chinese company presented them with while still acknowledging that it did, in fact, only aggravate an already difficult situation. Hence, given that the problematic connections to their Chinese superiors obviously lacked the qualities of reciprocal relationships, the money received could not be considered as proper salaries and the hardships endured while mixing sand, cement and gravel did not seem to result in the construction of a road. Still, when the monthly payment could be used, say, as down payment for a piece of land, it unfolded a virtual scenario very unlike that experienced in the present. Rather than indexing an untenable social relationship with the Chinese, it actualised a generative connection between the road and a future house. Although we might imagine the initial moment when the money was first received as indexing an employer–employee relationship, this was subsequently obviated by a new significant connection set-up between the road and a future house that was unfolded from the former (relationship) as the ‘real’ manifestation of salaries. The emerging house project thus transformed its own origin, as it were, by eliminating the Chinese counterpart as the source of the paid out money.

Anycast-Based Optimizations for Inter-Data-Center Interconnections [Invited

The cloud service delivery model is driving the data center (DC) architectural model towards a fully virtualized infrastructure acting as geographically distributed pools of shared resources, dynamically allocated to different services. Such a scenario calls for the anycast routing of virtual machine (VM) migration requests in order to select the destination server where the VMs will be migrated by taking into account the actual load of DC interconnections while addressing VM data transfer requirements. To this purpose, a management platform is presented that enables the dynamic connectivity setup between DCs without a priori indication of the destination server, according to the anycast principle. Specifically, data path allocation policies are proposed to select a proper inter-DC network path, and accordingly a destination server, to allow VM migration data to experience adequate delay performance. Using a simulation approach, the policies are compared in terms of success rate of delay-constrained data path setup as well as in terms of their capability to limit migration delay.

Short Pulse Generation With On-Chip Pulse-Forming Lines

We report our results on pulse-forming-line (PFL)-based CMOS pulse generator studies. Through simulations, we clarify the effects of PFL length, switch speed, and switch resistance on the output pulses. We model and analyze CMOS pulse generators with on-chip transmission lines (TLs) as PFLs and CMOS transistors as switches. In a 0.13- μm CMOS process with a 500- μm long PFL, post-layout simulations show that pulses of 10.4-ps width can be obtained. High-voltage and high-power outputs can be generated with other pulsed power circuits, such as Blumlein PFLs with stacked MOSFET switches. Thus, the PFL circuit significantly extends short and high-power pulse generation capabilities of CMOS technologies. A CMOS circuit with a 4-mm-long PFL is implemented in the commercial 0.13- μm technology. Pulses of ~116-ps duration and 205-300-mV amplitude on a 50-Ω load are obtained when the power supply is tuned from 1.2 to 1.6 V. Measurement connection setup is the main reason for the discrepancies among measurements, modeling, and simulation analyses.

Catastrophic Failures in a Backbone Network

When developing a backbone network protection scheme, one important consideration is the number of concurrent link failures against which protection should be provided. A carrier typically is concerned with links going down due to independent failure events such as fiber cuts or amplifier failures. When considering just these factors, a carrier has little incentive to offer protection against more than two concurrent link failures. However, when catastrophic events are also considered, it is shown that it is worthwhile to protect mission-critical connections against up to three concurrent link failures. It is also shown that a newly developed connection setup protocol can be effective in rapidly recovering from multiple link failures.

Exploiting Excess Capacity to Improve Robustness of WDM Mesh Networks

Excess capacity (EC) is the unused capacity in a network. We propose EC management techniques to improve network performance. Our techniques exploit the EC in two ways. First, a connection preprovisioning algorithm is used to reduce the connection setup time. Second, whenever possible, we use protection schemes that have higher availability and shorter protection switching time. Specifically, depending on the amount of EC available in the network, our proposed EC management techniques dynamically migrate connections between high-availability, high-backup-capacity protection schemes and low-availability, low-backup-capacity protection schemes. Thus, multiple protection schemes can coexist in the network. The four EC management techniques studied in this paper differ in two respects: when the connections are migrated from one protection scheme to another, and which connections are migrated. Specifically, Lazy techniques migrate connections only when necessary, whereas Proactive techniques migrate connections to free up capacity in advance. Partial Backup Reprovisioning (PBR) techniques try to migrate a minimal set of connections, whereas Global Backup Reprovisioning (GBR) techniques migrate all connections. We develop integer linear program (ILP) formulations and heuristic algorithms for the EC management techniques. We then present numerical examples to illustrate how the EC management techniques improve network performance by exploiting the EC in wavelength-division-multiplexing (WDM) mesh networks.

Statistical Approach for Fast Impairment-Aware Provisioning in Dynamic All-Optical Networks

Physical layer impairments (PLIs) need to be considered in the routing and wavelength assignment (RWA) process of all-optical networks to ensure the provisioning of good quality optical connections (i.e., lightpaths). A convenient way to model the impact of PLIs on the signal quality is to use the so-called Q-factor. In a dynamic provisioning environment, impairment-aware RWA (IA-RWA) algorithms include Q-factor evaluation in their on-line decisions on whether to accept a connection request or not. The Q-factor can be computed in either an approximated or an exact way. IA-RWA algorithms using an approximated Q-factor estimation (i.e., worst case) can be very fast and allow for a short setup delay. However, connection request blocking can be unnecessarily high because of the worst-case assumption for the Q-factor parameters. In contrast, an exact Q-factor computation results in a better blocking performance at the expense of a longer setup delay, mainly due to the time spent for the Q-factor computation itself. Moreover, an exact Q-factor approach requires extensions of the generalized multi-protocol label switching suite. To overcome these problems, we propose a statistical approach for fast impairment-aware RWA (SAFIR) computation. The evaluation results reveal that SAFIR improves the blocking probability performance compared to the worst-case scenario without adding extra computational complexity and, consequently, without increasing the connection setup delay.

Connection Setup Signaling Scheme with Flooding-Based Path Searching for Diverse-Metric Network

SUMMARY Connection setup on various computer networks is now achieved by GMPLS. This technology is based on the source-routing approach, which requires the source node to store metric information of the entire network prior to computing a route. Thus all metric information must be distributed to all network nodes and kept up-to-date. However, as metric information become more diverse and generalized, it is hard to update all information due to the huge update overhead. Emerging network services and applications require the network to support diverse metrics for achieving various communication qualities. Increasing the number of metrics supported by the network causes excessive processing of metric update messages. To reduce the number of metric update messages, another scheme is required. This paper proposes a connection setup scheme that uses flooding-based signaling rather than the distribution of metric information. The proposed scheme requires only flooding of signaling messages with requested metric information, no routing protocol is required. Evaluations confirm that the proposed scheme achieves connection establishment without excessive overhead. Our analysis shows that the proposed scheme greatly reduces the number of control messages compared to the conven

Live Endoscopy Demonstration Using Superfast Broadband Internet Connections: The Future of Medical Education and Conferences

See International Live Endoscopic Multichannel Demonstration Using Superfast Broadband Internet Connections by Sang Pyo Lee, Hang Lak Lee, Joon Soo Hahm, et al., on page 73-77 With rapid technologic advances in telecommunications and informatics, various technologies and tools for providing teleconferencing via Internet became available for real-time interaction. In the article by Lee et al.,1 a bidirectional transmission system with digital video transport system (DVTS) and Korea Advanced Research Network (KOREN) was used for two multicenter live endoscopy demonstrations in South Korea. DVTS enables transmission of digital video by applying additional compression and thus results in higher image quality.2,3 KOREN is a research and education network funded by Korean government and is more stable and faster than the generally used, commercial network.3 Therefore, it is no wonder that Lee et al.1 reported high satisfaction rate of 91% regarding both sound and image qualities. This finding is also in accordance with findings of a previous study.4 This study by Lee et al.1 is significant as one of few original articles on teleconferencing, especially using DVTS.1,4,5 This study enlightens gastrointestinal endoscopists on technologic advances in teleconferences and stimulates the interests in and need for the establishment of such system. However, it would have been better if the authors specified the parameters in which the participants showed satisfaction and which they were not satisfied. While teleconferencing using superfast broadband Internet connections is promising for everyone in healthcare, one should bear in mind that hardware, software, and dedicated personnel are essential for set-up and maintenance of superfast broadband Internet connections. Once established, this shall be an increasingly useful education and conference modality for both the novice and experienced endoscopists. In addition to live endoscopy demonstrations, there will be many more applications for superfast broadband Internet connections. We hope to see and experience these in a very near future.

Time Efficient Connection Formation Scheme in Bluetooth

 Abstract—Communications devices in a highly mobile environment need to minimize connection setup times in order to maximize useful data transfer. In this paper we analyze the device discovery process of Bluetooth, a technology that has potential in short-range, high mobility applications. In order to improve Bluetooth's performance in a mobile environment, it is desirable to reduce the amount of time it takes to set up connections between two devices. We suggest a simple change to the Bluetooth specification: using train A and train B (carrying of inquiry or paging messages) alternatively during inquiry and paging instead of using train A 256 times before using train B 256 times. This simple change can decrease connection setup time by a factor of approximately 3 without having deleterious effects on the overall system performance.

A P2P-to-UPnP Proxy Gateway Architecture for Home Multimedia Content Distribution

Deploying advanced home networking technologies and modern home-networked devices in residential environments provides a playground for new home applications and services. Because home multimedia entertainment is among the most essential home applications, this paper presents an appealing home media content sharing scenario: home-networked devices can discover neighboring devices and share local media content, as well as enormous amounts of Internet media content in a convenient and networked manner. This ideal scenario differs from traditional usages that merely offer local media content and require tedious manual operations of connection setup and file transfer among various devices. To achieve this goal, this study proposes a proxy gateway architecture for home multimedia content distribution. The proposed architecture integrates several functional mechanisms, including UPnP-based device discovery, home gateway, Internet media provision, and in-home media content delivery. This design addresses several inherent limitations of device heterogeneity and network interoperability on home and public networks, and allows diverse home-networked devices to play media content in an identical and networked manner. Prototypical implementation of the proposed proxy gateway architecture develops a proof-of-concept software, integrating a BitTorrent peer-to-peer client, a UPnP protocol stack, and a UPnP AV media server, as well as media distribution and management components on the OSGi home gateway platform. Practical demonstration shows the proposed design and scenario realization, offering users an unlimited volume of media content for home multimedia entertainment.

Parallel signaling-based fast restoration scheme in distributed optical networks

The fast parallel restoration (FPR) scheme is proposed to achieve the fast setup of restoration label switched path (LSP) in the distributed optical networks. The scheme is derived by dividing the whole restoration LSP into several segments of sub-LSP and triggering each sub-LSP along the new route to finish the signaling procedure concurrently, and subsequently merging all sub-LSPs into a whole LSP. The theoretical analysis and simulation results show that the FPR scheme outperforms the other two typical restoration schemes in terms of connection setup time.

Proposing a Standardized Protocol for Raw Biosignal Transmission

In this paper, we propose a standardized interface called TiA (TOBI interface A) to transmit raw biosignals, supporting multirate and block-oriented transmission of different kinds of signals from various acquisition devices (e.g., EEG, electrooculogram, near-infrared spectroscopy signals, etc.) at the same time. To facilitate a distinction between those kinds of signals, so-called signal types are introduced. TiA is a single-server, multiple-client system, whereby clients can connect to the server at runtime. Information transfer between client and server is divided into control and data connections. The control connections use transmission control protocol (TCP) and transmit extensible-markup-language (XML)-encoded meta information. The data transmission utilizes a user datagram protocol (UDP) or TCP with a binary data stream. A standardized handshaking procedure for the connection setup and a standardized binary data packet has been defined. Thus, a standardized layer, abstracting used hardware devices and facilitating distributed raw data transmission in a standardized way, has been evolved. A cross-platform library, implemented in C ++, is available for download.

Hierarchical routing and traffic grooming in IP/MPLS-based ASON/GMPLS multi-domain networks

Routing, connection setup, and path computation are well-known problems in multi-domain networks, which have been largely analyzed in pure IP (packet) networks. In circuit-switched optical multi-domain networks, there remain, however, a number of routing and path computation challenges. Traffic grooming means combining a number of low-speed traffic streams so that the high capacity of each lightpath may be used as efficiently as possible, as path computation implements the core of the grooming function, it is obvious that solutions for the traffic grooming problem in optical multi-domain networks are still not sufficiently investigated. In this study we propose a methodology to address the problems of routing, connection setup, and traffic grooming in optical multi-domain networks, which adapts a two-level hierarchical routing scheme and full-mesh topology abstraction algorithm to improve routing scalability and lower inter-domain blocking probabilities; additionally our proposed methodology adapts a scheme for traffic grooming in DWDM multi-domain networks to improve the resources usage. To test our proposed methodology we propose a detailed IP/MPLS-based ASON/GMPLS multi-domain multilayer test framework.