scholarly journals Applying Formal Modelling to the Specification and Testing of SDN Network Functionality

2021 ◽  
Author(s):  
◽  
Matthew Stevens

<p>Software Defined Networks offers a new paradigm to manage networks, one that favors centralised control over the distributed control used in legacy networks. This brings network operators potential efficiencies in capital investment, operating costs and wider choice in network appliance providers. We explore in this research whether these efficiencies apply to all network functionality by applying formal modelling to create a mathematically rigourous model of a service, a firewall, and using that model to derive tests that are ultimately applied to two SDN firewalls and a legacy stateful firewall. In the process we discover the only publicly available examples of SDN firewalls are not equivalent to legacy stateful firewalls and in fact create a security flaw that may be exploited by an attacker.</p>

2021 ◽  
Author(s):  
◽  
Matthew Stevens

<p>Software Defined Networks offers a new paradigm to manage networks, one that favors centralised control over the distributed control used in legacy networks. This brings network operators potential efficiencies in capital investment, operating costs and wider choice in network appliance providers. We explore in this research whether these efficiencies apply to all network functionality by applying formal modelling to create a mathematically rigourous model of a service, a firewall, and using that model to derive tests that are ultimately applied to two SDN firewalls and a legacy stateful firewall. In the process we discover the only publicly available examples of SDN firewalls are not equivalent to legacy stateful firewalls and in fact create a security flaw that may be exploited by an attacker.</p>


CORROSION ◽  
1954 ◽  
Vol 10 (9) ◽  
pp. 273-278
Author(s):  
AARON WACHTER

Abstract Every business can benefit from reduction of its losses due to corrosion. Awareness of all possible sources of such losses is essential. Unnecessary acceptance of losses is common from chronic corrosion which is tolerated as established custom, and from hidden or indirect effects of corrosion. The importance of corrosion damage is not always proportional to the volume of metal affected. The functional aspects of corrosion are listed. Analysis is made of the ways in which corrosion enters into the cost of doing business. Explanations are given of the direct and indirect ways corrosion may effect capital investment, operating costs, product sales, maintenance costs, overhead costs and market competitive condition of and company.


Agro Ekonomi ◽  
2017 ◽  
Vol 28 (1) ◽  
pp. 142
Author(s):  
Aditya Nugraha ◽  
Suhatmini Hardyastuti ◽  
Jangkung Handoyo Mulyo

Sijuk shrimp paste business is a business in processing rebon shrimp which is most commonly implemented in Belitung Regency. In this study, profi t analysis, investment feasibility, and sensitivity were used to draw the conclusions. The samples involve 25 shrimp paste businesses taken by using census method in Sungai Padang Village, District Sijuk, Belitung Regency. This area is also a central area for producing Sijuk shrimp paste. Census refers to periodic collection of information about the specifi c population from the entire population. Sampling is a method of collecting information from a sample that represents population. The result showed that the Sijuk shrimp paste businesses gives benefi ts because they had a gain of Rp.17.558.914,29 / year, the value of gross profi t ratio of 50.61%, the rate of return per capital investment of 1.02, and the return on the investments amounted to 74.58%. The Sijuk shrimp paste businesses are feasible to continue be had the value of discounted payback period of 1.57 years, the net present value of Rp.18.264.662,44, the internal rate of the return value of 35%, and the profi tability index of 1.78. From the results of the sensitivity analysis concluded that the Sijuk shrimp paste businesses are feasible to continue because the percentage of increase in the maximum operating costs still can be tolerated which is equal to 44,763% and the percentage of maximum reduction in the selling price of Sijuk shrimp paste still can be tolerated which is equal to 22.108%.


2017 ◽  
pp. 72-74
Author(s):  
Alexey Vladimirovich Vladykin ◽  
◽  
Nikolay Olegovich Frolov ◽  

2018 ◽  
Vol 44 (2) ◽  
pp. 241-256 ◽  
Author(s):  
David DeBoeuf ◽  
Hongbok Lee ◽  
Don Johnson ◽  
Maksim Masharuev

Purpose The purpose of this paper is to contribute to financial managers’ capital budgeting decision-making processes by proposing a new paradigm of capital investment appraisal. The expected return, required return structure of the proposed purchasing power return (PPR) methodology eliminates the many flaws associated with the competing internal rate of return (IRR) and modified IRR (MIRR) techniques. Design/methodology/approach The authors provide a new framework for examining long-term investment projects through a percentage return prism. Unlike that of IRR and MIRR, mathematical consistency with net present value (NPV) is a design requirement. Findings PPR eliminates the many flaws found in the IRR and MIRR methodologies, is mathematically consistent with NPV, and identifies positive-NPV investments forecasted to reduce the company’s purchasing power. These projects are acceptable under NPV, but flagged for additional review and potential rejection. Created to examine projects on a percentage return basis, PPR employs market-based inflation rates to convert all cash flows into constant purchasing power units of measure. From these units, an expected real return is estimated and compared to the project’s inflation-adjusted required return, resulting in an accept/reject decision consistent with that of NPV. Originality/value The proposed PPR is a new paradigm of capital investment appraisal that eliminates the many problems found in the IRR and MIRR techniques, is mathematically consistent with the NPV method, and helps financial decision makers examine investment projects on an expected percentage return basis. PPR also flags for further review projects expected to actually reduce the company’s purchasing power.


2019 ◽  
Vol 13 (1) ◽  
pp. 178-194 ◽  
Author(s):  
Miguel Ángel Barrera Pérez ◽  
Neider Yampol Serrato Losada ◽  
Elisa Rojas Sánchez ◽  
Giovani Mancilla Gaona

The growth of networks at a global level is inevitable due to the increase of users, devices and applications, such as: Internet of Things (IoT), processing and analysis of large amounts of information (Big Data), or streaming audio and video, which has demanded from the systems, greater storage resources and bandwidth. To this purpose, diverse paradigms have emerged for the centralized management of all the components of a network through fully administrable, centralized and dynamic technological platforms; among these is SDN (Software-Defined Networks). This document, consequently, establishes the state-of-art from a documentary research of a categorical type to be used as a frame of reference for research in the area of SDN by the Research Group of New Technologies of Social Application GIDENUTAS ascribed to the University Francisco Jose de Caldas. This is chronologically limited to a review, from 2007 until today, focused on the countries that have promoted the development and implementation of this new paradigm, using databases such as IEEE Xplore, Google Scholar, as well as documents from standardization organizations such as ONF and ITU.


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