Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major Telecomunicações). Faculdade de Engenharia. Universidade do Porto. 2009

Chemnitz, Techn. Univ., Diplomarb., 2000.

Many standards aimed at managing networks currently exist, and yet networks remain notoriously difficult to maintain. Template-based management systems go a long way towards solving this problem. By developing an XML based language to describe network elements, as well as the topology of a network, we can create tools that are free from vendor specific idiosyncrasies, and are capable of managing both today’s networks and those of the future.

Kompiuterinių tinklų valdytojai plačiai naudoja paprastąjį tinklų valdymo protokolą (toliau – SNMP), kuris padeda aptikti tinklų anomalijas ir įvairius gedimus. Norint patobulinti patį protokolą ir/ar stebėti specifinės tinklinės įrangos elgseną, būtina disponuoti šio protokolo monitoringo įrašais. Problema iškyla tada, kai norima gauti SNMP monitoringo įrašus iš realius kompiuterių tinklus valdančių organizacijų ir atlikti su jais įvairius tyrimus. SNMP monitoringo įrašai apima daug organizacijai jautrios informacijos saugumo požiūriu, todėl jų valdytojai neviešina. Bet koks šios informacijos atskleidimas sukelia realias grėsmes organizacijos informacijos saugumui. Siūlomas modelis leidžia atrinkti dominančią informaciją iš SNMP monitoringo įrašų visumos, anonimizuoti juos pagal pasirenkamus anonimiškumo kriterijus (priklausomai kokio formato duomenys anonimizuojami), išanalizuoti jų anonimiškumo laipsnį, gauti rekomendacijas ir jeigu anonimizuota informacija pakankamai saugi, perduoti trečioms šalims be grėsmės pakenkti disponuojamo tinklo saugumui. Pasinaudojus šiuo modeliu galima pasiekti tokį jautrios informacijos apsaugos lygį, kuris leistų apsaugoti informacijos tiekėją nuo jo tinklo silpnų vietų analizės ir galimų atakų. Kita vertus, būtų galima išsaugoti pakankamą kiekį naudingos informacijos, kuri būtų naudinga moksliniams bei analitiniams tyrimams. Naudojant skirtingus anonimizavimo metodus, priklausomai nuo informacijos atributų formato, būtų galima sustiprinti... [toliau žr. visą tekstą] / Computer networks owners widely use the simple network management protocol (SNMP), as it helps to identify varies anomalies and failures of computer networks. In the case of improvement of that method, or/and controlling the status or behaviour of specific network equipment, we must have logs of protocol. The problem arises when you want get them out from organizations, that manage computer networks. The SNMP monitoring records are not published, as any disclosure of real data would cause real threats to the organization and its security of information. The proposed model allows to anonymise, analize the level of anonymization, valuate it and if the anonymised data enough secure, forward it for public use without the threat to damage own computer network. It can be achieved a level of protection for sensitive information, by using this model, it will protect the suppliers and their networks from the real vulnerabilities analysis and possible attacks through them. On the other hand, it still could be saved a sufficient amount of information that would be useful for scientific and analytical research. Using the different anonymization techniques, depending on the attributes of the information format, it is possible to enhance or reduce the levels of security in order to increase or decrease the data lasting values. It gives the opportunity to network administrators or managers to decide, which data should be anonymized and how deep level of security must be reach before being... [to full text]

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / The integration of standard networking technologies into the test range allows for more capable and complex systems. As System Management provides the capability for dynamic allocation of resources, it is critical to support the level of network flexibility envisioned by the integrated Network-Enhanced Telemetry (iNET) project. This paper investigates the practical performance of managing the Telemetry Network System (TmNS) using the Simple Network Management Protocol (SNMP). It discusses the impacts and benefits of System Management as the size of the TmNS scales from small to large and as distributed and centralized management styles are applied. To support dynamic network states, it is necessary to be able to both collect the current status of the network and command (or modify the configuration of) the network. The management data needs to travel both ways over the telemetry link (in limited bandwidth) without interfering with critical data streams. It is important that the TmNS's status is collected in a timely manner so that the engineers are aware of any equipment failures or other problems; it is also imperative that System Management does not adversely affect the real-time delivery of data. This paper discusses measurements of SNMP traffic under various loading conditions. Statistics considered will include the performance of SNMP commands, queries, and events under various test article and telemetry network loads and the bandwidth consumed by SNMP commands, queries, and events under various conditions (e.g., pre-configuration, normal operation, and device error).

ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / The network switch is a critical element in the flight test network. All devices in the network are configured, synchronised and managed via the switch. In addition to this all acquired data is routed through the switch. For these reasons, the flight test network switch has always needed to be rugged and reliable with high throughput and simple intuitive setup. Ethernet technology and the move towards open standards within FTI systems have enabled flight test networks to become increasingly flexible and heterogeneous. Modern FTI networks may have different synchronisation and data transmission protocols running simultaneously. It is also important to quickly switch network configurations for different flight profiles and to enable new features to be easily added to existing installations. This paper examines the increasing network interoperability and flexibility challenges and discusses how the network switch is best placed to provide solutions.

Managing a network is a very big functional area along with performance, devicemaintenance, security, performance, monitoring, troubleshooting, plan of changeand etc. Among all of these monitoring plays a vital role. It can cover a wide area ofnetwork management. Monitoring is the only way to find out whether the networkis functioning according to plan. In order to know what is happening in a network,how its functioning at any given time, a network should have a logging system. Nowa day this logging activity is done by Network monitoring tool. It lets user know thestatus of the network at any given time. This logging can give the user a wide viewwhat can't be seen in general. For example the statistics of a week or month, even ayear. Monitoring is a very important issue in an organization network which aroseover the time.In this project we are going to implement some well known network monitoringtools in a real world scenario and we will investigate how this monitoring tool canhelp network administrators to monitor a network . Moreover, what kind ofinformation we can extract from a network by these tools.The purpose of this project is to get an overall idea about the importance of networkmonitoring and what are the facts need to be considered while monitoring anetwork. There are lots of pros and cons in monitoring a network. So choosing theappropriate tool for monitoring is very important. Monitoring a network with theleast effects on network performance is the best solution in case of monitoring.The outcome from these monitoring tools is a wide range of useful data andintegration of these data produces the status of the network at any give time.Moreover these data will be logged to create a statistical report. Different users suchas a network admin and organization can use this information from differentperspectives to make a network more efficient for users.

The main aim of this work was to study the issue of the SNMP protocol and MIB database in order to focus on management and configuration of MIB database using the SNMP protocol. The Master's thesis in detail describes especially creating a communications model of the Manager - Agent type in an OPNET Modeler. In this modeling tool we created exchange of information from the side of the Manager to the side of the Agent via SNMP packets. The Master's thesis is mainly focused on the creation of the SNMP packet according to defined rules, then on reading of information from the MIB database on the side of the Agent and saves this information to the Manager’s MIB database. Exchange of informations is realized via the messages of type GetRequest, GetNext and GetResponse. These models are programmed in language C/C++ and then implemented into the environment of OPNET Modeler.

Nach dem heutigen Wissenstand wird die Hämoxygenase-1 unter pathologischen Bedingunge der Niere, z.B. Ischämie, expremiert. Man nimmt an, dass die Hämoxygenase-1 eine Schutzfunktion für die Niere besitzt. Um dies zu bestätigen, führten wir eine tierexperimentelle Arbeit mit Ratten (n=101) durch in der wir durch Clamping der Nierenarterie ein reproduzierbares akutes ischämisches Nierenversagen induzierten. Bei einem Teil der Tiere wurde anschließend die Hämoxygenase durch injektion von SnMP gehemmt. Die Ratten wurden in 5 Gruppen randomisiert (Tag-0, Clamping+SnMP, Clamping+NaCl, Sham+SnMP, Sham+NaCl). In der Inulin/PAH-Clearance zeigte sich am ersten postoperativen Tag eine signifikante Verschlechterung bei den Clamping+SnMP-Tieren im Vergleich zu den Clamping+NaCl-Tieren. Die Ergebnisse wurden durch die erhöhten Retentionswerte und die erniedrigte PAH-Nettosekretion der Clamping+SnMP-Tiere unterstüzt. Die Gabe von SnMP hatte auf die nicht geclampte Niere bei den Sham-Tieren keinen Einfluss auf die Nierenfunktion. Dies zeigt, dass die Hämoxygenase-1 eine Schutzfunktion der Niere darstellt. / In pathologic situation like ischemia, it is standard of knowledge, that there is an exprimation of heme oxygenase-1 in the kidney. In studies, it is assumed, that heme oxygenase-1 has a protective function on the kidney. To validate this hypothesis we did an animal testet research in rats (n=101). We induced a reproducible acute ischemic renal failure with clampin of the renal arteries. In some of the rats we gave SnMP after the clamping to inhibit the function of heme oxygenase. The rats were randomized in 5 groups (day-0, Clamping+SnMP, Clamping+NaCl, Sham+SnMP, Sham+NaCl). On the first postoperative day we could messure a significant decline of the Inulin/PAH-Clearance in Clamping+SnMP-rats in comparison with Clamping+NaCl-rats. Parallel there was an elevation of urea/cratinine and a declined PAH-net-secretion in Clamping+SnMP-rats. The injection of SnMP in non-clamping-rats in the sham group had no effect on renal function. This study proofs that hame oxygenase-1 has a protective function in ischemic renal failure

Das akute Nierenversagen aufgrund ischämischer oder toxischer Nierenschädigung ist eine häufig auftretende Erkrankung mit einer hohen Mortalität. Immer noch sind die genauen Abläufe auf Zellebene nicht vollständig geklärt. Diese Arbeit befasst sich mit der Rolle der induzierbaren Hämoxygenase (HO-1) und ihrer Wechselwirkung mit der endothelialen Stickoxidsynthase (eNOS) im akuten ischämischen Nierenversagen. Dazu wurde im Rattenmodell mittels 45-minütigen Clamping beider Aa. renales ein ischämisches ANV induziert. Während eine Gruppe dem Clamping ohne weitere Intervention unterzogen wurde, ist einer weiteren Gruppe Zinn(VI)-Mesoporphyrin (SnMP), ein Inhibitor der HO-1, intraperitoneal appliziert worden. Eine dritte Gruppe mit Schein-Operation wurde als unbehandelte Kontrollgruppe parallel operiert und untersucht. Zur Bestimmung von renaler Filtrations- und Sekretionsfunktion wurden die Inulin-Clearance und die PAH-Clearance gemessen. Die Expression der untersuchten Enzyme aus HO/CO- und NOS/NO-System wurde mittels Westernblot quantitativ bestimmt. Der postinterventionelle Versuchszeitraum erstreckte sich über 14 Tage. In der unbehandelten Clamping-Gruppe zeigte sich ein Abfall von Inulin- und PAH-Clearance in der frühen postischämischen Phase, gefolgt von einer raschen Erholung und stetiger Verbesserung der Exkretionsfunktion im Verlauf des 14-tägigen Versuchs-intervalls. Die HO-1 zeigte einen Tag nach der Ischämie eine starke Überexpression, ebenso die im Hämkatabolismus wichtige Biliverdinreduktase (BVR). Die eNOS reagierte mit einer Hochregulierung, die sich in der Medulla langsamer entwickelte als in Kortex. Der gemeinsame Rezeptor der Signalstoffe CO und NO, die lösliche Guanylatzyklase (sGC), zeigte eine bedarfsgesteuerte leichte Hochregulation, möglicherweise ein Zeichen der endothelialen Dysfunktion mit zunächst nicht ausreichender NO-Bildung durch die eNOS. Die Clamping + SnMP-Gruppe erlitt eine stärkere Funktionseinschränkung nach der Intervention, was sich mit der Hemmung der HO-1 erklärt, regenerierte sich anschließend rasch wieder und hatte im Versuchsverlauf vergleichbare Funktionswerte wie die Clamping-Gruppe. Die HO-1 wurde ebenso akut hochreguliert, hielt aber die starken Überexpressionswerte während des Versuchszeitraums länger aufrecht als die Clamping-Gruppe. Diese Beobachtung lässt sich mit der Eigenschaft des SnMP erklären, dass es die Aktivität der HO-1 hemmt, ihre Expression aber steigert. Die Hochregulation der BVR war in dieser Gruppe geringer ausgeprägt. Die eNOS wurde in den mit SnMP behandelten Tieren weit schwächer exprimiert. Die sGC zeigte ähnliche Werte wie in der Clamping-Gruppe, wenn auch weniger stark reguliert. Die Beobachtung, dass sich eine Hemmung der HO-1 nicht nur auf die Enzyme ihres eigenen Signalweges und des Hämabbaus, der sGC und der BVR, auswirkt, sondern auch auf die der eNOS, bestätigt, dass das HO/CO- und das NOS/NO-System eng mit einander verknüpft sind. Dass dies nicht nur unter physiologischen Bedingungen, sondern insbesondere in der pathologischen Situation einer renalen Ischämie zum Tragen kommt, eröffnet Perspektiven, dass die dargestellten Ergebnisse dazu dienen könnten, neue Ansätze zu finden, um die endotheliale Dysfunktion im ANV kurativ zu beeinflussen. / The acute renal failure due to ischaemic or toxic kidney damage is a common disease with a high mortality. The exact processes at cell level are still not fully clarified. This work deals with the role of inducible heme oxygenase (HO-1) and its interaction with the endothelial nitric oxide synthase (eNOS) in the ischemic acute kidney failure (iARF). iARF was initiated in rats by 45-min artery clamping. While one group has undergone the clamping without further intervention, a further group was treated with tin(VI)-mesoporphyrin (SnMP), an inhibitor of HO 1, by intraperitoneal application. A third group was parallel operated as unhandled control group and investigated. The inulin clearance and the PAH clearance were measured to determine the renale filtration and secretion function. The expression of examined enzymes HO/CO and NOS/NO system was quantitatively determined using Westernblot. The test period extended over 14 days after operation. In the unhandled clamping group was a decrement of Inulin-and PAH clearance in the early post ischaemic phase, followed by a rapid recovery and constant improvement of the excretion function during the experimental period. The HO-1 showed on day 1 after the ischaemia a high expression, and so did the biliverdin reductase (BVR). The eNOS also responded with a high expression, slower developed in the medulla as in cortex. The receptor of both CO and NO, the soluble guanylyl cyclase (sGC), showed only a slightly higher expression, maybe a sign of the endothelialen dysfunction with first insufficient NO production by eNOS. The clamping/SnMP group underwent a stronger functional constraint after the intervention, what could be explained by the inhibition of HO 1. This group showed then a strong regeneration and had comparable values as the clamping group. The HO-1 shows a high expression, which was held up during the whole test period. This observation can be explained with the property of SnMP that inhibits the activity of HO 1, but increases its expression. The BVR high regulation is less pronounced in this group. The eNOS is far weaker expressed in the SnMP treated animals. The sGC shows similar values such as in the clamping group, but only indicated. The observation that an inhibition of HO 1 not only affects the enzymes of its own signal path and the heme degradation, sGC and BVR, but also eNOS and its signal path, confirms that the HO/CO and the NOS/NO system are linked closely with each other. That this comes about not only among physiological conditions, but especially in the pathological situation of a renale ischaemia, opens up prospects that the displayed results could serve to find curative influences on the endothelial dysfunction in the iARF.