TCP flow aware adaptive path switching in diffserv enabled MPLS networks

Cataloged from PDF version of article.We propose an adaptive flow-level multi-path routing-based traffic engineering solution for an IP backbone network carrying TCP/IP traffic. Incoming TCP flows are switched between two explicitly routed paths, namely the primary and secondary paths (PP and SP), for resilience and potential goodput improvement at the TCP layer. In the proposed architecture, PPs receive a preferential treatment over SPs using differentiated services mechanisms. The reason for this choice is not for service differentiation but for coping with the detrimental knock-on effect stemming from the use of longer SP that is well known for conventional network load balancing algorithms. Moreover, both paths are congestion-controlled using Explicit Congestion Notification marking at the core and Additive Increase Multiplicative Decrease rate adjustment at the ingress nodes. The delay difference between PP and SP is estimated using two per-egress rate-controlling buffers maintained at the ingress nodes for each path, and this delay difference is used to determine the path over which a new TCP flow will be routed. We perform extensive simulations using ns-2 in order to demonstrate the viability of the proposed distributed adaptive multi-path routing method in terms of per-flow TCP goodput. The proposed solution consistently outperforms the single-path routing policy and provides substantial per-flow goodput gains under poor PP conditions. Moreover, highest goodput improvements under the proposed scheme are achieved by flows that receive the lowest goodputs with single-path routing, while the performance of the flows with high goodputs with single-path routing does not deteriorate with the proposed path switching technique. Copyright # 2011 John Wiley & Sons, Ltd

Determining the effective constitutive parameters of finite periodic structures: photonic crystals and metamaterials

Cataloged from PDF version of article.A novel approach to find the effective electric and A novel approach to find the effective electric and magnetic parameters of finite periodic structures is proposed. The method uses the reflection coefficients at the interface between a homogenous half-space and the periodic structure of different thicknesses. The reflection data are then approximated by complex exponentials, from which one can deduce the wavenumber, and the effective electric and magnetic properties of the equivalent structure by a simple comparison to the geometrical series representation of the generalized reflection from a homogenous slab. Since the effective parameters are for the homogenous equivalent of the periodic structure, the results obtained are expected to be independent of the number of unit cells used in the longitudinal direction. Although the proposed method is quite versatile and applicable to any finite periodic structure, photonic crystals and metamaterials with metallic inclusions have been used to demonstrate the application of the method in this paper. © 2008 IEEE

NOBS: An ns2 based simulation tool for performance evaluation of TCP traffic in OBS networks

Performance evaluation of TCP traffic in OBS networks has been under intensive study, since TCP constitutes the majority of Internet traffic. As a reliable and publicly available simulator, ns2 has been widely used for studying TCP/IP networks; however ns2 lacks many of the components for simulating optical burst switching networks. In this paper, an ns2 based OBS simulation tool (nOBS), which is built for studying burst assembly, scheduling and contention resolution algorithms in OBS networks is presented. The node and link objects in OBS are extended in nOBS for developing optical nodes and optical links. The ingress, core and egress node functionalities are combined into a common optical node architecture, which comprises agents responsible for burstification, routing and scheduling. The effects of burstification parameters, e.g., burstification timeout, burst size and number of burstification buffers per egress node, on TCP performance are investigated using nOBS for different TCP versions and different network topologies

TCP flow aware adaptive path switching in diffserv enabled MPLS networks

We propose an adaptive flow-level multi-path routing-based traffic engineering solution for an IP backbone network carrying TCP/IP traffic. Incoming TCP flows are switched between two explicitly routed paths, namely the primary and secondary paths (PP and SP), for resilience and potential goodput improvement at the TCP layer. In the proposed architecture, PPs receive a preferential treatment over SPs using differentiated services mechanisms. The reason for this choice is not for service differentiation but for coping with the detrimental knock-on effect stemming from the use of longer SP that is well known for conventional network load balancing algorithms. Moreover, both paths are congestion-controlled using Explicit Congestion Notification marking at the core and Additive Increase Multiplicative Decrease rate adjustment at the ingress nodes. The delay difference between PP and SP is estimated using two per-egress rate-controlling buffers maintained at the ingress nodes for each path, and this delay difference is used to determine the path over which a new TCP flow will be routed. We perform extensive simulations using ns-2 in order to demonstrate the viability of the proposed distributed adaptive multi-path routing method in terms of per-flow TCP goodput. The proposed solution consistently outperforms the single-path routing policy and provides substantial per-flow goodput gains under poor PP conditions. Moreover, highest goodput improvements under the proposed scheme are achieved by flows that receive the lowest goodputs with single-path routing, while the performance of the flows with high goodputs with single-path routing does not deteriorate with the proposed path switching technique. Copyright © 2011 John Wiley & Sons, Ltd

Combined use of prioritized AIMD and flow-based traffic splitting for robust TCP load balancing

In this paper, we propose an AIMD-based TCP load balancing architecture in a backbone network where TCP flows are split between two explicitly routed paths, namely the primary and the secondary paths. We propose that primary paths have strict priority over the secondary paths with respect to packet forwarding and both paths are rate-controlled using ECN marking in the core and AIMD rate adjustment at the ingress nodes. We call this technique "prioritized AIMD". The buffers maintained at the ingress nodes for the two alternative paths help us predict the delay difference between the two paths which forms the basis for deciding on which path to forward a new-coming flow. We provide a simulation study for a large mesh network to demonstrate the efficiency of the proposed approach in terms of the average per-flow goodput and byte blocking rates. © Springer-Verlag Berlin Heidelberg 2004

AIMD-based online MPLS traffic engineering for TCP flows via distributed multi-path routing

With this paper, we propose a distributed online traffic engineering architecture for MPLS networks. In this architecture, a primary and secondary MPLS LSP are established from an ingress LSR to every other egress LSR. We propose to split the TCP traffic between the primary and secondary paths using a distributed mechanism based on ECN marking and AIMD-based rate control. Inspired by the random early detection mechanism for active queue management, we propose a random early reroute scheme to adaptively control the delay difference between the primary and secondary LSPS. Considering the adverse effect of packet reordering on TCP performance for packet-based load balancing schemes, we propose that the TCP splitting mechanism operates on a per-flow basis. Using flow-based models developed for Internet traffic and simulations, we show that flow-based distributed multi-path traffic engineering outperforms on a consistent basis the case of a single path in terms of per-flow goodputs. Due to the elimination of out-of-order packet arrivals, flow-based splitting also enhances TCP performance with respect to packet-based splitting especially for long TCP flows that are hit hard by packet reordering. We also compare and contrast two queuing architectures for differential treatment of data packets routed over primary and secondary LSPS in the MPLS data plane, namely first-in-first-out and strict priority queuing. We show through simulations that strict priority queuing is more effective and relatively more robust with respect to the changes in the traffic demand matrix than first-in-first-out queuing in the context of distributed multi-path routing

Učinci liječenja fenetil esterom kavene kiseline na reumatološke pokazatelje i metabolizam željeza u štakorica s izazvanom šećernom bolešću.

Diabetology and rheumatology have much in common, including many biochemical features. Diabetic cases suffer excessively from common musculoskeletal conditions. The present study aimed to explore the association between the caffeic acid phenethyl ester (CAPE) treatment and the standard parameters of diabetic and rheumatologic controls. Serum anti-streptolysin-O (ASO), C-reactive protein (CRP), rheumatoid factor (RF) titers and glucose (GLU), cholesterol (CHOL), triglyceride (TG), high density lipoprotein (HDL), very low density lipoprotein (VLDL), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), sodium (Na), potassium (K), chloride (Cl), calcium (Ca), phosphorus (P), uric acid (UA), iron (Fe), iron-binding capacity (IBC), total iron-binding capacity (TIBC) and superoxide dismutase (SOD) levels were measured in 22 female Wistar-Albino rats. The animals were divided into three groups: group 1: non-diabetic rats as control; group 2: streptozotocin (STZ)-induced, untreated diabetic rats; and group 3: STZ-induced, CAPE-treated diabetic rats. Levels of GLU were increased in group 2. ASO values were decreased in group 3. TG and VLDL levels were increased in group 3 compared with the group 1. Higher UA levels were detected in group 3 compared with group 2. The levels of Fe and TIBC were decreased in group 3. The results of the present study indicate the reducing effect of CAPE on the serum levels of diabetic and rheumatologic parameters in diabetic rats.Dijabetologija i reumatologija imaju mnoge sličnosti, uključujući biokemijske procese. Oboljeli od dijabetesa pate od teških stanja mišićno-koštanog sustava. U ovom radu istražena je povezanost između liječenja fenetil esterom kavene kiseline i standardnih pokazatelja koji se kontroliraju pri dijabetičnim i reumatoidnim bolestima. Kod 22 Wistar-Albino štakorice mjereni su: serumski anti-streptolizin-O (ASO), C-reaktivni protein (CRP), titar reumatoidnog faktora (RF), zatim razina glukoze (GLU), kolesterola (CHOL), triglicerida (TG), lipoproteina visoke gustoće (HDL), lipoproteina vrlo niske gustoće (VLDL), alkalne fosfataze (ALP), gamaglutamil transferaze (GGT), natrija (Na), kalija (K), klorida (Cl), kalcija (Ca), fosfora (P), mokraćne kiseline (UA), željeza (Fe), kapaciteta vezanja željeza (IBC), ukupnog kapaciteta vezanja željeza (TIBC) i superoksid dismutaze (SOD). Životinje su bile podijeljene u tri skupine: 1. štakorice bez dijabetesa (kontrolna skupina), 2. neliječene štakorice s dijabetesom izazvanim streptozotocinom (STZ) i 3. štakorice sa streptozotocin (STZ) - izazvanim dijabetesom liječenim fenetil esterom kavene kiseline. Razine GLU bile su povećane u skupini 2. ASO vrijednosti bile su snižene u skupini 3. Razine TG i VLDL bile su povišene u skupini 3 u usporedbi s razinama u skupini 1. Više razine UA utvrđene su u skupini 3 u usporedbi sa skupinom 2. Razine Fe i TIBC bile su snižene u skupini 3. Rezultati pokazuju reducirajuće učinke fenetil estera kavene kiseline na razinu dijabetičnih i reumatoloških pokazatelja u serumu štakorica sa šećernom bolešću izazvanom streptozotocinom

Computational study of droplets rising using Lattice Boltzmann Model

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Multi relaxation time lattice Boltzmann method is implemented to study unsteady multiphase flows of two immiscible fluids. D2Q9 lattice arrangement for two dimensional flows is employed to investigate lighter fluid droplets rising in heavier fluid. Density distribution functions for each fluid and distribution functions for the coloring step identifying the location of interface separating each immiscible fluid will be used to simulate the dynamics of the droplets and the velocity field of each phase. Buoyancy and other interactive forces between phases are modeled to predict the evolution of droplets as they are rising. No-slip no penetration boundary conditions and periodic boundary conditions are considered in transient flow simulations of multi-phase immiscible fluid for a range of various arrangements of droplets. The effect of the boundaries on the droplets dynamics will be presented.dc201

How to teach usage of equipments in a remote laboratory

European Remote Radio Laboratory (ERRL) is an e-learning project for students, teachers and technicians of the universities who will use the very important devices of this laboratory remotely. These devices are very expensive to buy and can be broken easily while they have been using by the people who does not really know how to use them professionally. As a solution we have developed an e-learning system which aims to support the ERRL learners while studying on how to use equipments in the system. The system is developed according to the electronic performance support systems (EPSS) approach. An EPSS is a computer-based, well-structured system which improves the performance of individuals. It is an electronic infrastructure that contains, stores and distributes personal (individual) or corporate knowledge to enable people to reach necessary levels of performance in the fastest possible time and with minimum teaching support of other people. This paper discusses how the content for such a system is developed and how this content is interactively used in the EPSS platform. The technical details of the developed EPSS are also discussed in this study. We believe that this paper will help instructional system designers for designing different alternatives to improve learners' performance. © 2007 IEEE

Teaching usage of equipments in a remote laboratory

Remote laboratories are technologies that aim to increase the effectiveness of educational programs. European Remote Radio Laboratory (ERRL) is an e-learning project for students, teachers and technicians who will use very important devices of a radio frequency laboratory remotely. As a solution we have developed an e-learning system which aims to support the ERRL learners while studying on how to use equipments in the system. The system is developed according to the electronic performance support system (EPSS) approach. An EPSS is a computer-based, well-structured system which improves the performance of individuals. It is an electronic infrastructure that contains, stores and distributes personal (individual) or corporate knowledge to enable people to reach necessary levels of performance in the fastest possible time and with minimum teaching support of other people. This paper discusses how the content for such a system is developed and how this content is interactively used in the EPSS platform. The technical details of the developed EPSS are also discussed in this study. We believe that this paper will help instructional system designers for designing different alternatives to improve learners' performance