Accuracy and Dynamics of Hash-Based Load Balancing Algorithms for Multipath Internet Routing

This paper studies load balancing for multipath Internet routing. We focus on hash-based load balancing algorithms that work on the flow level to avoid packet reordering which is detrimental for the throughput of transport layer protocols like TCP. We propose a classification of hash-based load balancing algorithms, review existing ones and suggest new ones. Dynamic algorithms can actively react to load imbalances which causes route changes for some flows and thereby again packet reordering. Therefore, we investigate the load balancing accuracy and flow reassignment rate of load balancing algorithms. Our exhaustive simulation experiments show that these performance measures depend significantly on the traffic properties and on the algorithms themselves. As a consequence, our results should be taken into account for the application of load balancing in practice

Implementation and Evaluation of Activity-Based Congestion Management Using P4 (P4-ABC)

Activity-Based Congestion management (ABC) is a novel domain-based QoS mechanism providing more fairness among customers on bottleneck links. It avoids per-flow or per-customer states in the core network and is suitable for application in future 5G networks. However, ABC cannot be configured on standard devices. P4 is a novel programmable data plane specification which allows defining new headers and forwarding behavior. In this work, we implement an ABC prototype using P4 and point out challenges experienced during implementation. Experimental validation of ABC using the P4-based prototype reveals the desired fairness results

Pre-Congestion Notification (PCN) Architecture

This document describes a general architecture for flow admission and termination based on pre-congestion information in order to protect the quality of service of established, inelastic flows within a single Diffserv domain.\u

Requirements for Signaling of Pre-Congestion Information in a Diffserv Domain

Pre-Congestion Notification (PCN) is a means for protecting quality of service for inelastic traffic admitted to a Diffserv domain. The overall PCN architecture is described in RFC 5559. This memo describes the requirements for the signaling applied within the PCN- domain: (1) PCN-feedback-information is carried from the PCN-egress-node to the Decision Point; (2) the Decision Point may ask the PCN-ingress-node to measure, and report back, the rate of sent PCN-traffic between that PCN-ingress-node and PCN-egress-node. The Decision Point may be either collocated with the PCN-ingress-node or a centralized node (in the first case, (2) is not required). The signaling requirements pertain in particular to two edge behaviors, Controlled Load (CL) and Single Marking (SM)

Pre-Congestion Notification (PCN) Boundary-Node Behavior for the Single Marking (SM) Mode of Operation

Pre-Congestion Notification (PCN) is a means for protecting the quality of service for inelastic traffic admitted to a Diffserv domain. The overall PCN architecture is described in RFC 5559. This memo is one of a series describing possible boundary-node behaviors for a PCN-domain. The behavior described here is that for a form of measurement-based load control using two PCN marking states: not-marked and excess-traffic-marked. This behavior is known informally as the Single Marking (SM) PCN-boundary-node behavior

Overview of Pre-Congestion Notification Encoding

The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic flows within a Diffserv domain. On every link in the PCN-domain, the overall rate of PCN-traffic is metered, and PCN-packets are appropriately marked when certain configured rates are exceeded. Egress nodes provide decision points with information about the PCN-marks of PCN-packets that allows them to take decisions about whether to admit or block a new flow request, and to terminate some already admitted flows during serious pre-congestion. The PCN working group explored a number of approaches for encoding this pre-congestion information into the IP header. This document provides details of those approaches along with an explanation of the constraints that apply to any solution

Continuous granulation and drying : Building a comprehensive process understanding based on Quality by Design principles

This thesis investigated a complete integrated continuous granulation and drying line including the process units continuous dosing, continuous twin screw wet granulation and continuous fluid bed drying, considering also the quality of resulting tablets. In the first part of the thesis (chapters 4, 5 and 6), a process understanding for the integrated continuous line was built investigating all three process units. Powder characterisation of starting materials of a broad range of different excipients and binary mixtures using volumetric dosing mode proved the importance of the hopper fill level for an accurate dosing rate. Furthermore, it could be shown, that both material attributes bulk density and flowability of the excipient or binary mixture are of high importance and therefore critical for the resulting dosing rate and accuracy of dosing rate over time. Regarding the continuous twin screw wet granulation, two different formulations were investigated and compared in terms of their granulation behaviour. Both formulations were therefore granulated and dried using the integrated continuous granulation and drying line. One formulation included cellulose, the other formulation explicitly did not. For both investigated formulations granulation moisture level was identified to be a critical process parameter and to have a high impact on the particle size distribution of the produced granules. Interestingly the other two investigated granulation-related process parameters powder feed rate and barrel fill level appeared to be of minor importance for resulting granules material attributes and tablet quality attributes. Characteristics of the two formulations and their granulation behaviour were thoroughly investigated and significant differences could be identified and described. Non beneficial granulation behaviour could be overcome and resulting tablets showed improved tabletability as expected. As the third unit in the process-chain, the continuous fluid bed dryer was evaluated using the same formulations as being used for the investigation of twin screw wet granulation process. The drying performance was investigated by evaluation of the effect of three main process parameters on granule material attributes and tablet quality attributes. Particle fine fraction and residual water content of the dried granules could be identified to be critical material attributes with regard to tabletability and compressibility. It could also be shown that independent of the used formulation both mentioned material attributes could directly and systematically be controlled by the investigated process parameters. Within development of a new pharmaceutical product scale-up is an important aspect to be considered in addition to the process understanding presented in the first part of the thesis. Therefore, in the second part of the thesis (chapter 7), a scale up approach for three continuous granulation and drying lines was investigated. For twin screw wet granulation process, enhanced scaling aspects were analysed showing e.g. the influence of Froude number on formation of coarse particle fraction. Within systematic evaluation of the applied scaling approach the drying capacity parameter DCP could be established which can further be utilized to adjust the drying capacity across different scales of continuous fluid bed driers. Statistical evaluation of the DoEs per scale enabled to calculate process design spaces for each scale; targeting on identified critical material attributes of the granules that result in good tabletability and compressibility performance. Overall, it could be shown that scaling of the three different continuous granulation and drying lines was successful using the presented scaling approach. A special feature of continuous manufacturing compared to traditional batch processing is the consideration of time-dependent effects. Out of that reason, the third part of the thesis (chapter 8) deals with long-term effects evaluated during long-term runs using the integrated continuous granulation and drying line. For the continuous dosing unit a fast, more frequent refilling of the hopper was identified to be key for an accurate dosing rate. With regard to the twin screw wet granulation process, it was found that an efficient temperature control is essential to avoid high shear and friction energies inside the granulator. Parameters were identified indicating the stability and healthiness of the granulation system. Abrasion and friction effects are special, mechanical risks of the twin screw wet granulation process. In the last part of the thesis (chapter 9) that process risk was considered by applying wall friction measurements with a Schulze ring shear tester. Deducted from the evaluation of wall friction angle of different formulations a case study made it possible to link the measured wall friction angles to the calculated specific mechanical energy during twin screw granulation and to the observed visual defect rate of tablets occurring due to abrasion effects during granulation. Thus, wall friction measurements could serve as useful tool to assess abrasion effects inside the twin screw granulator

Insulator-to-metal transition in Kondo insulators under strong magnetic field

Magnetization curve and changes of the single-particle excitation spectra by magnetic field are calculated for the periodic Anderson model at half-filling in infinite spatial dimension by using the exact diagonalization method. It is found that the field-induced insulator-to-metal transition occurs at a critical field $H_c$, which is of the order of the single ion Kondo temperature. The transition is of first order, but could be of second order in the infinite system size limit. These results are compared with the experiments on the Kondo insulator YbB$_{12}$.Comment: 11 pages, REVTEX, no figures; 7 figures available on request; To appear in Phys. Rev. B, Mar.15, 199

Calculation of Optical Conductivity of YbB12_{12} using Realistic Tight-Binding Model

Based on the previously reported tight-binding model fitted to the LDA+U band calculation, optical conductivity of the prototypical Kondo insulator YbB$_{12}$ is calculated theoretically. Many-body effects are taken into account by the self-consistent second order perturbation theory. The gross shape of the optical conductivity observed in experiments are well described by the present calculation, including their temperature-dependences.Comment: 6 pages, 7 figures, use jpsj2.cls, to appear in J. Phys. Soc. Jpn. Vol.73, No.10 (2004

OIDC2OIDC^2: Open Identity Certification with OpenID Connect

OpenID Connect (OIDC) is a widely used authentication standard for the Web. In this work, we define a new Identity Certification Token (ICT) for OIDC. An ICT can be thought of as a JSON-based, short-lived user certificate for end-to-end user authentication without the need for cumbersome key management. A user can request an ICT from his OpenID Provider (OP) and use it to prove his identity to other users or services that trust the OP. We call this approach $OIDC^2$ and compare it to other well-known end-to-end authentication methods. Unlike certificates, $OIDC^2$ does not require installation and can be easily used on multiple devices, making it more user-friendly. We outline protocols for implementing $OIDC^2$ based on existing standards. We discuss the trust relationship between entities involved in $OIDC^2$, propose a classification of OPs' trust level, and propose authentication with multiple ICTs from different OPs. We explain how different applications such as videoconferencing, instant messaging, and email can benefit from ICTs for end-to-end authentication and recommend validity periods for ICTs. To test $OIDC^2$, we provide a simple extension to existing OIDC server software and evaluate its performance