Distributed-and-split data-control extension to SCSI for scalable storage area networks

Security mechanisms in a transport layer protocol

Broadband technologies have made multi-hop wireless communications a reality. Loss-prone multi-hop networks pose challenges to link and transport layer protocols. Wireless links need to export low link-latencies, high goodputs and low residual loss rates to effectively enable interactive applications. Current link protocols with high ARQ persistence incur high latencies that impair such applications. We propose LL-HARQ, a link protocol that meets these goals. However, under high and bursty loss rates even LL-HARQ exports a small residual loss rate that could accumulate over multiple hops. Since TCP-SACK cannot handle error rates greater than 5%, a transport protocol (LT-TCP) designed for loss tolerance can be used under such cases. We provide insights into the structuring of the building blocks and balance between error-protection functions at the two layers and examine the case for cross-layer co-operation. Finally, we demonstrate that the combination achieves improved end-end performance (delay, loss and goodput) over traditional approaches.

SCSI protocol is the protocol of choice for block storage management. Different transport mechanisms such as parallel SCSI, Fibre Channel, iSCSI and Infiniband can be used to transfer SCSI protocol data. Distance and connectivity limitations are the key drawbacks of parallel SCSI. Therefore, Fibre Channel, Infiniband and iSCSI (SCSI over TCP) are competing to emerge as the dominant next generation SCSI transport mechanism. By analyzing the different components of a network protocol, this paper evaluates whether Fibre Channel, Infiniband and iSCSI are (a) suitable for gigabit wire speeds (b) scalable across thousands of interconnected devices and (c) satisfy the needs of storage environments and storage protocols.

Recently, dynamic adaptive streaming over HTTP (DASH) has become an increasingly popular way to view video over the Internet. In particular compared to other video streaming services these DASH approaches deliver superior QoE to viewers. This is due to improved video segment selection. Generally, Transmission Control Protocol (TCP) CUBIC is the defacto transport layer protocol use by DASH. To improve the robustness of the transport layer to network congestion many other TCP variants were implemented such as Compound TCP and BBR. Nevertheless some were made to work specifically in LAN environments for example Agile-SD. However, recently another transport layer protocol User Datagram Protocol (UDP) has been used in Google’s QUIC implementation. To date no work has be found giving the performance of these transport layer protocols with DASH. In this paper we test the performance of Agile-SD, CUBIC, Compound TCP, BBR and QUIC using the BBA, MPC, Pensieve and Oboe DASH approaches. Experiments simulate congested bottleneck link conditions common at household routers where families view multiple videos at the same time. We observe Oboe and Agile-SD is the most promising combination with CUBIC and Pensieve next. However, even though QUIC was touted to have superior transport layer performance by Google it was the worst performing.

The transport layer in the network protocol stack serves as a liaison between the application and the underlying network. Any quality of service provided by the network thus has to be effectively translated by the transport layer protocol in order to be enjoyed by the applications. In this article, we argue for a fundamental rethinking of the transport layer design to facilitate such QoS delivery. We identify the key requirement for a QoS enabling transport layer protocol as the ability to effectively handle multiplicity in terms of user differentiation levels, network resources, and service models. However, TCP, the transport layer protocol predominantly used in the Internet, is unable to support such multiplicity due to its single-state design. We extend TCP to a parallel transport layer protocol called parallel TCP (pTCP) that can tackle the different dimensions of multiplicity, and hence enable varying classes of QoS to applications. We discuss the applicability of pTCP in three specific domains with different levels of network support for QoS, and present simulation results substantiating our arguments.

This paper investigates the effect of cognitive operations in the physical (PHY) layer on the throughput of the transport layer in Cognitive Mobile Ad Hoc Networks (CoMANETs). The focus is on the use of soft sensing to enhance secondary users capacity in the PHY layer. A new transport layer protocol is proposed which updates the Congestion Window (CW) efficiently according to the power and rate adaptation strategy of the soft sensing scheme. The expected throughput is derived and compared to the case where the transport layer is oblivious to the use of soft sensing, as well as to a benchmark case from the literature where only hard sensing is used. Results show significant throughput improvements due to soft sensing in general. These improvements increase with proper adaptation of the transport layer protocol.

With the growing demand of Internet services, network operators have put significant efforts to improve network error resilience and efficiency. Since there exist different wired/wireless technologies for Internet access such as digital subscriber line (DSL), Ethernet, and worldwide interoperability for microwave access (WiMax), a mobile host can use multiple access networks simultaneously with multipath transmission. Taking the advantage of heterogeneous environment, multipath transmission through the Internet can improve service reliability and network flexibility. Ensuring a reliable end-to-end connection oriented communication with satisfactory quality of service (QoS) and maintaining congestion control and flow control are the main responsibilities of the Transmission Control Protocol (TCP), the dominant transport layer protocol in the Internet. In this paper, we survey the state-of-the-art of multipath transmission techniques for QoS provisioning in wireless Internet access, focusing on the end-to-end transport layer protocols. The main challenges for the design of multipath TCP are reviewed, and the existing transport layer congestion control schemes are categorized. Multipath TCP and stream control transmission protocol (SCTP)-based transport layer protocols are discussed, and their limitations and/or impractical assumptions are addressed. Open research issues on the development of an effective, efficient, and practical multipath TCP protocol are summarized.

Cognitive radio technology has been used to efficiently utilize the spectrum in wireless networks. Although many research studies have been done recently in the area of cognitive radio networks (CRNs), little effort has been made to propose a simulation framework for CRNs. In this paper, a simulation framework based on NS2 (CogNS) for cognitive radio networks is proposed. This framework can be used to investigate and evaluate the impact of lower layers, i.e., MAC and physical layer, on the transport and network layers protocols. Due to the importance of packet drop probability, end-to-end delay and throughput as QoS requirements in real-time reliable applications, these metrics are evaluated over CRNs through CogNS framework. Our simulations demonstrate that the design of new network and transport layer protocols over CRNs should be considered based on CR-related parameters such as activity model of primary users, sensing time and frequency.

Today’s Cross Domain Communication (CDC) infrastructure largely consists of guards built to vendor specifications. Such an infrastructure often fails to provide adequate protections for CDC workflows involving Service Oriented Architectures. Focusing on the transport layer and oblivious to the context of the information exchanges, the guards often rely on rudimentary filtering techniques that require frequent human intervention to adjudicate messages. In this paper, we present a set of key requirements and design principles for a Service Oriented Cross Domain Security Infrastructure in form of a CDC Reference Architecture, featuring domain-associated guards as active workflow participants. This reference architecture will provide the foundation for the development of protocols and ontologies enabling runtime coordination among CDC elements, leading to more secure, effective, and interoperable CDC solutions.

A Brief Study on Data Communication and Computer Networks

Utilizing multiple paths between network hosts (such as robots or sensors) will improve network performance, path availability and connection reliability. This paper presents a cross layer multiple path approach named proxy server based multipath connection. Multiple paths are set up via a set of intermediate proxy servers using IP tunneling. Packet distribution and reassembly are achieved by inserting a thin layer between the network layer and the transport layer. On the sender side, packets are distributed across multiple paths based on predefined striping schemes. On the receiver side, a double buffer approach is proposed to solve the TCP sequence number persistent reordering problem. A prototype was implemented on the Linux and Windows systems. Experimental results show that the proposed approach can improve network throughput and is robust to network congestion and link breakage.

In transport layer protocols over ATM networks, a packet is discarded when one or more cells are lost in that packet, and the destination node then requires its source to retransmit the corrupted packet. Therefore, once one of cells constituting a packet is lost, its subsequent cells of the corrupted packet waste network resources. In this paper, we propose the throughput analysis in transport layer with selective cell discard schemes and selective repeat ARQ. In the analysis, we suppose that sources steadily generate cells due to the packet retransmission; the resulting state will be referred to as source saturation, which makes the analysis very tractable from a computational point of view. Through some numerical results, we can clarify the impacts of the average number of packet length, the buffer size and the number of sources on the throughput performance of selective cell discard schemes.

Physical Layer, Data Link Layer, Network Layer, Transport Layer, and Application Layer in Cognitive Radio Networks

Borrowing the open system interconnection (OSI) model of internet protocol and the 5W theory in communication studies, the links in the international communication of acupuncture-moxibustion can be classified into seven layers: physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer, therefore it is built an OSI model of international communication system of acupuncture-moxibustion. It is pointed out that present international communication system of acupuncture-moxibustion is similar to the user datagram protocol (UDP) in internet technology. Evidence-based medicine (EBM) plays a key role to modernize acupuncture- moxibustion theory based upon its clinical effects. According to phenomenon-taking by classified analogy, it is found that the PICO model of EBM agrees pretty well with the "three-way handshakes" mechanism of the internet transmission control protocol (TCP), which is promising to construct an international discourse of acupuncture-moxibustion compatible with western medicine. Thus it will benefit to explore the scientific connotation of acupuncture-moxibustion theory and significantly improve the international prestige of acupuncture-moxibustion.

The large demand of bandwidth due to new and future applications from services being implemented such as smart grid (SG), smart cities (SC), and the Internet of Things has triggered a focus of interest from the scientific community on issues related to the planning and scalability of the communications infrastructure. In this paper, we present three new and important contributions regarding the deployment of FiWi networks that support users who benefit from the services provided by SG and SC. We first propose a planning model, and then formulate a mixed linear programming optimization model using multistage stochastic programming, and finally propose an algorithm, called MOA–FiWi, which has the capacity to handle medium and large instances of the problem and give feasible solutions for the optimization process, where scalability indices between 85%–95% are reached with respect to the projected stochastic values. The proposed model considers the scalability and capital and operating expense, as well as the uncertainty management in the different stages of time–space through multistage stochastic programming. The proposed model presents flexibility in decision making as the time stages progress. This allows for the planning of green fields, as well as the updating of networks that already have communication infrastructure.