A fine-grained protection mechanism in object-based operating systems

Author(s):  
S. Shigeta ◽  
T. Tanimori ◽  
K. Shimizu ◽  
H. Ashihara
2021 ◽  
Author(s):  
Mirja Shahriar Enan

The present computer network has been evolved into a complex structure with a growing challenge to manage and scale modern day’s requirements. A new approach to tackle these difficulties is SDN, which empowers network with programmability and is designed to perform fine grained traffic forwarding decisions. However, similar to the need of traditional networks, fault tolerance is necessary to achieve high availability. In this thesis, we propose a link protection method based on the Segment Routing (SR) for rapid failure recovery in OpenFlow based SDN. Our proposed scheme performs local recovery at the switch level without the controller intervention, thus significantly reducing the total recovery time. Additionally, it reduces initial load on the controller while proactively computing the backup paths by minimizing the algorithm complexity. Moreover, memory efficiency is achieved by using a per-link protection with aggregated flow rules instead of traditional per-flow based protection mechanism. In Segment Routing, we may encounter the limitation on the size of the label stack, known as Segment List Depth (SLD). Therefore, we also propose an efficient label encoding algorithm to mitigate the SLD impact.


2020 ◽  
Vol 34 (07) ◽  
pp. 11555-11562 ◽  
Author(s):  
Chuanbin Liu ◽  
Hongtao Xie ◽  
Zheng-Jun Zha ◽  
Lingfeng Ma ◽  
Lingyun Yu ◽  
...  

Delicate attention of the discriminative regions plays a critical role in Fine-Grained Visual Categorization (FGVC). Unfortunately, most of the existing attention models perform poorly in FGVC, due to the pivotal limitations in discriminative regions proposing and region-based feature learning. 1) The discriminative regions are predominantly located based on the filter responses over the images, which can not be directly optimized with a performance metric. 2) Existing methods train the region-based feature extractor as a one-hot classification task individually, while neglecting the knowledge from the entire object. To address the above issues, in this paper, we propose a novel “Filtration and Distillation Learning” (FDL) model to enhance the region attention of discriminate parts for FGVC. Firstly, a Filtration Learning (FL) method is put forward for discriminative part regions proposing based on the matchability between proposing and predicting. Specifically, we utilize the proposing-predicting matchability as the performance metric of Region Proposal Network (RPN), thus enable a direct optimization of RPN to filtrate most discriminative regions. Go in detail, the object-based feature learning and region-based feature learning are formulated as “teacher” and “student”, which can furnish better supervision for region-based feature learning. Accordingly, our FDL can enhance the region attention effectively, and the overall framework can be trained end-to-end without neither object nor parts annotations. Extensive experiments verify that FDL yields state-of-the-art performance under the same backbone with the most competitive approaches on several FGVC tasks.


2019 ◽  
Vol 26 (4) ◽  
pp. 545-567
Author(s):  
T. Manzocchi ◽  
L. Zhang ◽  
P. W. D. Haughton ◽  
A. Pontén

Deep-water lobe deposits are arranged hierarchically and can be characterized by high net:gross ratios but poor sand connectivity due to thin, but laterally extensive, shale layers. This heterogeneity makes them difficult to represent in standard full-field object-based models, since the sands in an object-based model are not stacked compensationally and become connected at a low net:gross ratio. The compression algorithm allows the generation of low-connectivity object-based models at high net:gross ratios, by including the net:gross and amalgamation ratios as independent input parameters. Object-based modelling constrained by the compression algorithm has been included in a recursive workflow, permitting the generation of realistic models of hierarchical lobe deposits. Representative dimensional and stacking parameters collected at four different hierarchical levels have been used to constrain a 250 m-thick, 14 km2 model that includes hierarchical elements ranging from 20 cm-thick sand beds to more than 30 m-thick lobe complexes. Sand beds and the fine-grained units are represented explicitly in the model, and the characteristic facies associations often used to parameterize lobe deposits are emergent from the modelling process. The model is subsequently resampled without loss of accuracy for flow simulation, and results show clearly the influence of the hierarchical heterogeneity on drainage and sweep efficiency during a water-flood simulation.


2018 ◽  
Vol 13 (1) ◽  
pp. 186-196 ◽  
Author(s):  
Cong Zuo ◽  
Jun Shao ◽  
Joseph K. Liu ◽  
Guiyi Wei ◽  
Yun Ling

Author(s):  
Kenichi Kourai ◽  
Takeshi Azumi ◽  
Shigeru Chiba

In Infrastructure-as-a-Service (IaaS) clouds, stepping-stone attacks via hosted virtual machines (VMs) are critical for the credibility. This type of attack uses compromised VMs as stepping stones for attacking the outside hosts. For self-protection, IaaS clouds should perform active responses against stepping-stone attacks. However, it is difficult to stop only outgoing attacks at edge firewalls, which can only use packet headers. In this paper, we propose a new self-protection mechanism against stepping-stone attacks, which is called xFilter. xFilter is a packet filter running in the virtual machine monitor (VMM) underlying VMs and achieves pinpoint active responses by using VM introspection. VM introspection enables xFilter to directly obtain information on packet senders inside VMs. On attack detection, xFilter automatically generates filtering rules based on packet senders. To make packet filtering with VM introspection efficient, we introduced several optimization techniques. Our experiments showed that the performance degradation due to xFilter was usually less than 16%.


2021 ◽  
Author(s):  
Mirja Shahriar Enan

The present computer network has been evolved into a complex structure with a growing challenge to manage and scale modern day’s requirements. A new approach to tackle these difficulties is SDN, which empowers network with programmability and is designed to perform fine grained traffic forwarding decisions. However, similar to the need of traditional networks, fault tolerance is necessary to achieve high availability. In this thesis, we propose a link protection method based on the Segment Routing (SR) for rapid failure recovery in OpenFlow based SDN. Our proposed scheme performs local recovery at the switch level without the controller intervention, thus significantly reducing the total recovery time. Additionally, it reduces initial load on the controller while proactively computing the backup paths by minimizing the algorithm complexity. Moreover, memory efficiency is achieved by using a per-link protection with aggregated flow rules instead of traditional per-flow based protection mechanism. In Segment Routing, we may encounter the limitation on the size of the label stack, known as Segment List Depth (SLD). Therefore, we also propose an efficient label encoding algorithm to mitigate the SLD impact.


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