Network Performance Analysis Using Cisco VIRL

This thesis provides a detailed analysis of the effects of TCP and UDP traffic over a LAN and WAN medium. In addition, it also analyses some real time applications like audio, video and web browsing that is affected by TCP traffic while sharing a bottleneck node and/or link resources. As network industry is growing continuously, the network administrator should be aware of TCP and UDP traffic that is traversing through their network. The analysis and monitoring of the traffic is crucial as it directly affects the performance of the network. Finding a cause for the poor performance of the network is quite important because it gives an idea to troubleshoot and resolve the issues effectively. In this thesis, we have created topologies using Cisco’s Virtual Internet Routing Lab (VIRL) [7]. They replicate an organizational infrastructure with client-server environment in LAN and WAN. Routing protocols such as OSPF and BGP are used to mimic the real world internet. A built-in LXC-iperf tool is used to generate the TCP and UDP traffic. During the generation of the traffic, various parameters are changed or controlled to see their effect on the network performance. As a learning and informative research, this thesis considers several Quality of Service (QoS) parameters that characterize the performance of an overall network. In particular, this thesis obtains packet loss, throughput, and jitter as QoS parameters when the resource has both TCP and UDP traffics simultaneously. We have examined, the effects on (i) TCP throughput and packet loss and (ii) UPD packet loss and jitter of (a) real time audio, (b) video, and (c) web browsing applications. These parameters examine how the traffic be manipulated to keep minimum packet loss, minimum jitter and maximum throughput. It is needless to say that all are competing with each other (TCP/UDP traffic) for sharing bottleneck resources. We have used a sample time of 15 seconds for each of our experimental results presented in this thesis. Our analysis shows that the best performance of the real time video and audio application is obtained when we select large size packet but its size being less than MTU of the link (without reducing the data rates). Similarly, in case of web browsing, we notice that throughput increases by increasing the window size and decreasing the latency. Efficient outcomes with the traffic analysis are achieved only if the experiments are carried out with adequate amount of attention. Overall, this work has provided us a great learning opportunity in the area of network performance using Cisco’s VIRL tool

Evaluating Serverless Computing

Function as a Service (FaaS) is gaining admiration because of its way of deploying the computations to serverless backends in the different clouds. It transfers the complexity of provisioning and allocating the necessary resources for an application to the cloud providers. The cloud providers also give an illusion of always availability of resources to the users. Among the cloud providers, AWS serverless platform offers a new paradigm for developing cloud applications without worrying about the underlying hardware infrastructure. It manages not only the resource provisioning and scaling of an application but also provides an opportunity to reimagine the cloud infrastructure as more secure, reliable, and cost-effective. Due to the lack of standardized benchmarks, serverless functions must rely on ad-hoc solutions to build cost-efficient and scalable applications. However, with the development of the SeBS framework, we can test, evaluate and do performance analysis of different cloud providers. Various researches have been conducted to differentiate the serverless platforms among the cloud providers. However, there is no research conducted so far within the AWS Lambda service in ARM64 architecture and between its different CPU architectures (x86 and ARM64). Thus in this thesis, we have analyzed the perf-cost, latency, and cold startup overhead for both x86 and ARM64 architecture. We have conducted a meticulous evaluation of the perf-cost analysis in different sections. Our results show that increasing the code size and complexity directly affects the perf-cost metrics in both x86 and ARM64 architecture. However, at each invocation, either cold or warm startup, ARM64 is performing better than x86. Furthermore, our work showed the behavior of cold and warm startups at each architecture for any specific workload. Taking the viewpoint of a serverless user, we also conduct experiments to show the effect of complexity on memory usage at both x86 and ARM64 architecture. We found that each architecture consumes nearly the same amount of memory for any particular workload regardless of invocation methods -cold and warm. In addition, we observed that cold invocation and ARM architecture would be efficient configurations for any specific workload regarding memory usage. Our analysis also shows that the input size directly impacts perf-cost metrics. Regarding the latency, ARM64 needs less time than ARM64 irrespective of invocation methods. However, if we look closer, a warm startup’s latency is less than a cold one. Therefore, the most efficient configuration for any specific workload would be a warm invocation and ARM architecture. Similarly, in the case of cold startup overhead, our results illustrate that for any specific workload, ARM64 has lower execution and provider time overhead than x86. However, these overheads decrease with the increment of complexity due to high memory consumption at higher complex workloads. Therefore, we can say that our work and results provide a fair and transparent baseline for the comparative evaluation of each AWS architecture. Overall, this thesis has provided us with a great learning opportunity in serverless computing assessment

Thermodynamics, structure, and transport properties of the MgO–Al\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e liquid system

Seven liquids along the MgO–Al O join were simulated at zero pressure in temperature (T) range 2000–6000 K using the first-principles molecular dynamics method. The simulation results show continuous changes in various physical properties with composition (molar fraction of alumina, X). They suggest that the binary mixing tends to be nearly ideal with no immiscibility along the entire join. The calculated mean coordination numbers of MgO and AlO polyhedra gradually increase with increasing X, for example, their respective values are 4.6 and 4.3 at/near the MgO end, 5.2 and 4.6 for MgAl O spinel composition, and 5.5 and 4.8 at/near the alumina end. The mean O–O coordination number remains almost unchanged along the join at ≥ 12 implying a closely packed arrangement. In contrast, all other coordination types including O–Mg and O–Al change dramatically along the join. The calculated self-diffusion and viscosity coefficients vary much less with composition (by a factor of 4 or less along the entire join) than with temperature (by two orders of magnitudes over the T range considered). Their T–X variations can be well described by the respective Arrhenius equations with composition-dependent activation energies and pre-exponential parameters. While the alumina and silica components are considered to play a similar role with regard to the structural polymerization of amorphous aluminosilicates, our results show that they influence the melt transport properties very differently. Therefore, the general notion that these two oxide components play an equivalent role in multicomponent magmatic melts is not unambiguous. 2 3 2

Density‐Pressure Profiles of Fe‐Bearing MgSiO 3

Density is a key property controlling the chemical state of Earth\u27s interior. Our knowledge about the density of relevant melt compositions is currently poor at deep-mantle conditions. Here we report results from first-principles molecular-dynamics simulations of Fe-bearing MgSiO liquids considering different valence and spin states of iron over the whole mantle pressure conditions. Our simulations predict the high-spin to low-spin transition in both ferrous and ferric iron in the silicate liquid to occur gradually at pressures around 100 GPa. The calculated iron-induced changes in the melt density (about 8% increase for 25% iron content) are primarily due to the difference in atomic mass between Mg and Fe, with smaller contributions (\u3c2%) from the valence and spin states. A comparison of the predicted density of mixtures of (Mg,Fe)(Si,Fe)O and (Mg,Fe)O liquids with the mantle density indicates that the density contrast between the melt and residual-solid depends strongly on pressure (depth): in the shallow lower mantle (depths \u3c 1,000 km), the melt is lighter than the solids, whereas in the deep lower mantle (e.g., the D″ layer), the melt density exceeds the mantle density when iron content is relatively high and/or melt is enriched with Fe-rich ferropericlase. 3