27 results on '"Katsikas, Georgios P."'
Search Results
2. What You Need to Know About (Smart) Network Interface Cards
- Author
-
Katsikas, Georgios P., Barbette, Tom, Chiesa, Marco, Kostić, Dejan, Maguire, Gerald Q., Jr., Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Woeginger, Gerhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Hohlfeld, Oliver, editor, Lutu, Andra, editor, and Levin, Dave, editor
- Published
- 2021
- Full Text
- View/download PDF
3. What You Need to Know About (Smart) Network Interface Cards
- Author
-
Katsikas, Georgios P., primary, Barbette, Tom, additional, Chiesa, Marco, additional, Kostić, Dejan, additional, and Maguire, Gerald Q., additional
- Published
- 2021
- Full Text
- View/download PDF
4. Profiling and accelerating commodity NFV service chains with SCC
- Author
-
Katsikas, Georgios P., Maguire Jr., Gerald Q., and Kostić, Dejan
- Published
- 2017
- Full Text
- View/download PDF
5. P5: Event-driven Policy Framework for P4-based Traffic Engineering
- Author
-
Famelis, Panagiotis, primary, Katsikas, Georgios P., additional, Katopodis, Vasilios, additional, Natalino, Carlos, additional, Renom, Lluis Gifre, additional, Martinez, Ricardo, additional, Vilalta, Ricard, additional, Klonidis, Dimitrios, additional, Monti, Paolo, additional, King, Daniel, additional, and Farrel, Adrian, additional
- Published
- 2023
- Full Text
- View/download PDF
6. Cloud-Native SDN Network Management for Beyond 5G Networks with TeraFlow
- Author
-
Vilalta, Ricard, Muñoz, Raül, Casellas, Ramon, Martínez, Ricardo, Fernández-Palacios, Juan Pedro, Katsikas, Georgios P., Zinner, Thomas, Øverby, Harald, González-Díaz, Sergio, Lønsethagen, Hakon, Pulido, José-Miguel, King, Daniel, and Carapellese, Nicola
- Subjects
NO KEYWORDS - Abstract
TeraFlow proposes a novel secured transport Software Defined Networking (SDN) controller based on a microservice architecture. The objective is to foster innovation around SDN controller and evolve them to be suitable for beyond 5G networks. This paper presents two TeraFlow scenarios that involve automated network management to demonstrate its feasibility. The first scenario focuses on the necessary transformation of a network operator to support beyond 5G technologies. From edge, up to the transport network, SDN controllers need to include more dinamicity to support operator requirements for new types of connectivity services. The second scenario demonstrates interdomain connectivity services in an automotive scenario. In this scenario, novel techniques for domain inter-connection will be studied, as well as the load balancing of the connectivity service requests will be evaluated at cloud-scale., Grant numbers : AURORAS - Autonomic and disaggregated optical networks leveraging edge computing and photonic technologies (RTI2018-099178-B-I00) project.
- Published
- 2021
- Full Text
- View/download PDF
7. What You Need to Know About (Smart) Network Interface Cards
- Author
-
UCL - SST/ICTM/INGI - Pôle en ingénierie informatique, Katsikas, Georgios P., Barbette, Tom, Chiesa, Marco, Kostić, Dejan, Maguire, Gerald Q., UCL - SST/ICTM/INGI - Pôle en ingénierie informatique, Katsikas, Georgios P., Barbette, Tom, Chiesa, Marco, Kostić, Dejan, and Maguire, Gerald Q.
- Abstract
Network interface cards (NICs) are fundamental components of modern high-speed networked systems, supporting multi-100 Gbps speeds and increasing programmability. Offloading computation from a server’s CPU to a NIC frees a substantial amount of the server’s CPU resources, making NICs key to offer competitive cloud services. Therefore, understanding the performance benefits and limitations of offloading a networking application to a NIC is of paramount importance. In this paper, we measure the performance of four different NICs from one of the largest NIC vendors worldwide, supporting 100 Gbps and 200 Gbps. We show that while today’s NICs can easily support multi-hundred-gigabit throughputs, performing frequent update operations of a NIC’s packet classifier—as network address translators (NATs) and load balancers would do for each incoming connection—results in a dramatic throughput reduction of up to 70 Gbps or complete denial of service. Our conclusion is that all tested NICs cannot support high-speed networking applications that require keeping track of a large number of frequently arriving incoming connections. Furthermore, we show a variety of counter-intuitive performance artefacts including the performance impact of using multiple tables to classify flows of packets.
- Published
- 2021
8. Metron : High-Performance NFV Service Chaining Even in the Presence of Blackboxes
- Author
-
Katsikas, Georgios P., Barbette, Tom, Kostic, Dejan, Maguire Jr., Gerald Q., Steinert, Rebecca, Katsikas, Georgios P., Barbette, Tom, Kostic, Dejan, Maguire Jr., Gerald Q., and Steinert, Rebecca
- Abstract
Deployment of 100 Gigabit Ethernet (GbE) links challenges the packet processing limits of commodity hardware used for Network Functions Virtualization (NFV). Moreover, realizing chained network functions (i.e., service chains) necessitates the use of multiple CPU cores, or even multiple servers, to process packets from such high speed links. Our system Metron jointly exploits the underlying network and commodity servers' resources: (i) to offload part of the packet processing logic to the network, (ii) by using smart tagging to setup and exploit the affinity of traffic classes, and (iii) by using tag-based hardware dispatching to carry out the remaining packet processing at the speed of the servers' cores, with zero inter-core communication. Moreover, Metron transparently integrates, manages, and load balances proprietary "blackboxes" together with Metron service chains. Metron realizes stateful network functions at the speed of 100 GbE network cards on a single server, while elastically and rapidly adapting to changing workload volumes. Our experiments demonstrate that Metron service chains can coexist with heterogeneous blackboxes, while still leveraging Metron's accurate dispatching and load balancing. In summary, Metron has (i) 2.75-8× better efficiency, up to (ii) 4.7× lower latency, and (iii) 7.8× higher throughput than OpenBox, a state-of-the-art NFV system., QC 20210712, European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 770889), Swedish Foundation for Strategic Research (SSF)
- Published
- 2021
- Full Text
- View/download PDF
9. Int5Gent: An integrated end-to-end system platform for verticals and data plane solutions beyond 5G
- Author
-
Klonidis, Dimitrios, primary, Apostolopoulos, Dimitris, additional, Katsikas, Georgios P., additional, Giannoulis, Giannis, additional, Kanta, Konstantina, additional, Tokas, Kostas, additional, Xirofotos, Thanos, additional, Munoz, Raul, additional, Moscatelli, Francesca, additional, Torfs, Guy, additional, Vagionas, Christos, additional, Lopez, David Larrabeiti, additional, He, Zhongxia Simon, additional, Sterle, Janez, additional, Levi, Dotan, additional, Lyberopoulos, George, additional, Alvarez, Victor Lopez, additional, Trouva, Eleni, additional, Leiba, Yigal, additional, Vilajosana, Xavier, additional, Teres Casals, J. Carles, additional, and Avramopoulos, Hercules, additional
- Published
- 2021
- Full Text
- View/download PDF
10. TeraFlow: Secured Autonomic Traffic Management for a Tera of SDN flows
- Author
-
Vilalta, Ricard, primary, Munoz, Raul, additional, Casellas, Ramon, additional, Martinez, Ricardo, additional, Lopez, Victor, additional, de Dios, Oscar Gonzalez, additional, Pastor, Antonio, additional, Katsikas, Georgios P., additional, Klaedtke, Felix, additional, Monti, Paolo, additional, Mozo, Alberto, additional, Zinner, Thomas, additional, Overby, Harald, additional, Gonzalez-Diaz, Sergio, additional, Lonsethagen, Hakon, additional, Pulido, Jose-Miguel, additional, and King, Daniel, additional
- Published
- 2021
- Full Text
- View/download PDF
11. Metron : High-performance NFV Service Chaining Even in the Presence of Blackboxes
- Author
-
UCL - SST/ICTM/INGI - Pôle en ingénierie informatique, Katsikas, Georgios P., Barbette, Tom, Kostić, Dejan, Maguire, JR. Gerald Q., Steinert, Rebecca, UCL - SST/ICTM/INGI - Pôle en ingénierie informatique, Katsikas, Georgios P., Barbette, Tom, Kostić, Dejan, Maguire, JR. Gerald Q., and Steinert, Rebecca
- Abstract
Deployment of 100Gigabit Ethernet (GbE) links challenges the packet processing limits of commodity hardware used for Network Functions Virtualization (NFV). Moreover, realizing chained network functions (i.e., service chains) necessitates the use of multiple CPU cores, or even multiple servers, to process packets from such high speed links. Our system Metron jointly exploits the underlying network and commodity servers’ resources: (i) to offload part of the packet processing logic to the network, (ii) by using smart tagging to setup and exploit the affinity of traffic classes, and (iii) by using tag-based hardware dispatching to carry out the remaining packet processing at the speed of the servers’ cores, with zero inter-core communication. Moreover, Metron transparently integrates, manages, and load balances proprietary “blackboxes” together with Metron service chains. Metron realizes stateful network functions at the speed of 100GbE network cards on a single server, while elastically and rapidly adapting to changing workload volumes. Our experiments demonstrate that Metron service chains can coexist with heterogeneous blackboxes, while still leveraging Metron’s accurate dispatching and load balancing. In summary, Metron has (i) 2.75–8× better efficiency, up to (ii) 4.7× lower latency, and (iii) 7.8× higher throughput than OpenBox, a state-of-the-art NFV system.
- Published
- 2020
12. Metron
- Author
-
Katsikas, Georgios P., primary, Barbette, Tom, additional, Kostić, Dejan, additional, Maguire, JR. Gerald Q., additional, and Steinert, Rebecca, additional
- Published
- 2020
- Full Text
- View/download PDF
13. Metron : NFV service chains at the true speed of the underlying hardware
- Author
-
Katsikas, Georgios P., Barbette, Tom, Kostic, Dejan, Steinert, R., Maguire Jr., Gerald Q., Katsikas, Georgios P., Barbette, Tom, Kostic, Dejan, Steinert, R., and Maguire Jr., Gerald Q.
- Abstract
In this paper we present Metron, a Network Functions Virtualization (NFV) platform that achieves high resource utilization by jointly exploiting the underlying network and commodity servers’ resources. This synergy allows Metron to: (i) offload part of the packet processing logic to the network, (ii) use smart tagging to setup and exploit the affinity of traffic classes, and (iii) use tag-based hardware dispatching to carry out the remaining packet processing at the speed of the servers’ fastest cache(s), with zero intercore communication. Metron also introduces a novel resource allocation scheme that minimizes the resource allocation overhead for large-scale NFV deployments. With commodity hardware assistance, Metron deeply inspects traffic at 40 Gbps and realizes stateful network functions at the speed of a 100 GbE network card on a single server. Metron has 2.75-6.5x better efficiency than OpenBox, a state of the art NFV system, while ensuring key requirements such as elasticity, fine-grained load balancing, and flexible traffic steering, QC 20200324
- Published
- 2019
14. RSS++: load and state-aware receive side scaling
- Author
-
Barbette, Tom, Katsikas, Georgios P., Maguire Jr., Gerald Q., Kostic, Dejan, Barbette, Tom, Katsikas, Georgios P., Maguire Jr., Gerald Q., and Kostic, Dejan
- Abstract
While the current literature typically focuses on load-balancing among multiple servers, in this paper, we demonstrate the importance of load-balancing within a single machine (potentially with hundreds of CPU cores). In this context, we propose a new load-balancing technique (RSS++) that dynamically modifies the receive side scaling (RSS) indirection table to spread the load across the CPU cores in a more optimal way. RSS++ incurs up to 14x lower 95th percentile tail latency and orders of magnitude fewer packet drops compared to RSS under high CPU utilization. RSS++ allows higher CPU utilization and dynamic scaling of the number of allocated CPU cores to accommodate the input load, while avoiding the typical 25% over-provisioning. RSS++ has been implemented for both (i) DPDK and (ii) the Linux kernel. Additionally, we implement a new state migration technique, which facilitates sharding and reduces contention between CPU cores accessing per-flow data. RSS++ keeps the flow-state by groups that can be migrated at once, leading to a 20% higher efficiency than a state of the art shared flow table., QC 20191126
- Published
- 2019
- Full Text
- View/download PDF
15. RSS++ : load and state-aware receive side scaling
- Author
-
UCL - SST/ICTM/INGI - Pôle en ingénierie informatique, Barbette, Tom, Katsikas, Georgios P., Maguire, Gerald Q., Kostić, Dejan, UCL - SST/ICTM/INGI - Pôle en ingénierie informatique, Barbette, Tom, Katsikas, Georgios P., Maguire, Gerald Q., and Kostić, Dejan
- Abstract
While the current literature typically focuses on load-balancing among multiple servers, in this paper, we demonstrate the importance of load-balancing within a single machine (potentially with hundreds of CPU cores). In this context, we propose a new load-balancing technique (RSS++) that dynamically modifies the receive side scaling (RSS) indirection table to spread the load across the CPU cores in a more optimal way. RSS++ incurs up to 14x lower 95th percentile tail latency and orders of magnitude fewer packet drops compared to RSS under high CPU utilization. RSS++ allows higher CPU utilization and dynamic scaling of the number of allocated CPU cores to accommodate the input load while avoiding the typical 25% over-provisioning. RSS++ has been implemented for both (i) DPDK and (ii) the Linux kernel. Additionally, we implement a new state migration technique which facilitates sharding and reduces contention between CPU cores accessing per-flow data. RSS++ keeps the flow-state by groups that can be migrated at once, leading to a 20% higher efficiency than a state of the art shared flow table.
- Published
- 2019
16. NFV Service Chains at the Speed of the Underlying Commodity Hardware
- Author
-
Katsikas, Georgios P.
- Subjects
synthesis ,processavlastning ,tjänstekedjor ,paketmärkning ,Communication Systems ,zero inter-core communication ,tagging ,ingen inter-CPU-kommunikation ,service chains ,Telekommunikation ,NFV ,syntetisering ,Datorsystem ,100GbE ,line-rate ,Computer Systems ,offloading ,Telecommunications ,länkkapacitet ,Kommunikationssystem - Abstract
Link speeds in networks will in the near-future reach and exceed 100 Gbps. While available specialized hardware can accommodate these speeds, modern networks have adopted a new networking paradigm, also known as Network Functions Virtualization (NFV), that replaces expensive specialized hardware with open-source software running on commodity hardware. However, achieving high performance using commodity hardware is a hard problem mainly because of the processor-memory gap. This gap suggests that only the fastest memories of today’s commodity servers can achieve the desirable access latencies for high speed networks. Existing NFV systems realize chained network functions (also known as service chains) mostly using slower memories; this implies a need for multiple additional CPU cores or even multiple servers to achieve high speed packet processing. In contrast, this thesis combines four contributions to realize NFV service chains with dramatically higher performance and better efficiency than the state of the art. The first contribution is a framework that profiles NFV service chains to uncover reasons for performance degradation, while the second contribution leverages the profiler’s data to accelerate these service chains by combining multiplexing of system calls with scheduling strategies. The third contribution synthesizes input/output and processing service chain operations to increase the spatial locality of network traffic with respect to a system’s caches. The fourth contribution combines the profiler’s insights from the first contribution and the synthesis approach of the third contribution to realize NFV service chains at the speed of the underlying commodity hardware. To do so, stateless traffic classification operations are offloaded into available hardware (i.e., programmable switches and/or network cards) and a tag is associated with each traffic class. At the server side, input traffic classes are classified by the hardware based upon the values of these tags, which indicate the CPU core that should undertake their stateful processing, while ensuring zero inter-core communication. With commodity hardware, this thesis realizes Internet Service Provider-level service chains and deep packet inspection at a line-rate 40 Gbps and stateful service chains at the speed of a 100 GbE network card on a 16 core single server. This results in up to (i) 4.7x lower latency, (ii) 8.5x higher throughput, and (iii) 6.5x better efficiency than the state of the art. The techniques described in this thesis are crucial for realizing future high speed NFV deployments. Länkhastigheter i nätverk kommer inom en snar framtid att nå och överstiga 100 Gbps. Medan existerande specialiserad hårdvara numera kan tillgodose dessa hastigheter, tillämpas i moderna nätverk även ett nytt nätverksparadigm känt som funktionsvirtualisering av nätverk (NFV), som ersätter dyr specialiserad hårdvara med öppen källkodsprogramvara som körs på kostnadseffektiv, icke-specialiserad, vanlig dator (s.k. råvaru-enheter). Att uppnå hög prestanda med hjälp av standardmaskinvara är ett svårt problem, huvudsakligen på grund av prestandaskillnader mellan processor och minne. Denna skillnad medför att endast de snabbaste cache-minnena av idag måste användas för att uppnå högsta prestanda med minsta möjliga fördröjningar i höghastighetsnätverk. Sammankopplade nätverksfunktioner (s.k. tjänstekedjor) i existerande NFV-system använder mestadels långsammare minne, vilket innebär att ytterligare CPU-kärnor eller servrar behövs för att uppnå motsvarande höghastighetsprestanda vid hanteringen av datapaket. I denna avhandling kombineras fyra bidrag som möjliggör NFV-tjänstekedjor med betydligt högre prestanda och effektivitet jämfört med den senaste tekniken. Det första bidraget är ett ramverk som profilerar NFV-tjänstekedjor för att identifiera av orsaken till prestandaförsämringar, medan det andra bidraget utnyttjar profildata för att snabba upp tjänstekedjorna genom att kombinera multiplexering av systemanrop med olika schemaläggnings-strategier. Det tredje bidraget syntetiserar indata/utdata och tjänstekedje-operationer för att öka den spatiala lokaliteten av nätverkstrafiken i förhållande till systemets cacher. Det fjärde bidraget kombinerar profilerings-resultat från det första bidraget och syntetiseringsmetoden från det tredje bidraget för att möjliggöra NFV-tjänstekedjor kapabla att hantera datatrafik med samma höga överföringshastighet som den underliggande maskinvaran. För att göra detta överförs tillståndslösa trafikklassificerings-operationer till tillgänglig maskinvara (d.v.s. programmerbara switchar och/eller nätverkskort) med en indikativ märkning kopplad till varje trafikklass. På serverns sida klassificeras inkomna trafikklasser baserad på märkningen, följt av tillståndsstyrd bearbetning av paketen i tillgängliga CPU-kärnor utan inbördes kommunikation mellan kärnorna. Med användning av endast vanlig maskinvara uppnås i den här avhandlingen tjänstekedjor på Internet-leverantörsnivå och djupa paketinspektioner vid en hastighet av 40 Gbps, motsvarande den underliggande linjehastighet bearbetning, samt tillståndsstyrda tjänstekedjor med hastigheten motsvarande ett 100 GbE-nätverkskort på en server. Detta resulterar i upp till (i) 4,7x lägre latens, (ii) 8,5x högre dataöverföring och (iii) 6,5x ökad effektivitet jämfört med den senaste tekniken. Denna avhandling är avgörande för att förverkliga framtida höghastighetsnätverk. QC 20180829 European Union Horizon 2020 BEhavioural BAsed forwarding (BEBA) European Research Council (ERC) PROPHET Swedish Foundation for Strategic Research Wallenberg AI, Autonomous Systems, and Software Program (WASP)
- Published
- 2018
17. RSS++
- Author
-
Barbette, Tom, primary, Katsikas, Georgios P., additional, Maguire, Gerald Q., additional, and Kostić, Dejan, additional
- Published
- 2019
- Full Text
- View/download PDF
18. Metron: NFV Service Chains at the True Speed of the Underlying Hardware
- Author
-
Katsikas, Georgios P., Barbette, Tom, Kostic, Dejan, Steinert, Rebecca, Maguire Jr., Gerald Q., Katsikas, Georgios P., Barbette, Tom, Kostic, Dejan, Steinert, Rebecca, and Maguire Jr., Gerald Q.
- Abstract
In this paper we present Metron, a Network Functions Virtualization (NFV) platform that achieves high resource utilization by jointly exploiting the underlying network and commodity servers’ resources. This synergy allows Metron to: (i) offload part of the packet processing logic to the network, (ii) use smart tagging to setup and exploit the affinity of traffic classes, and (iii) use tag-based hardware dispatching to carry out the remaining packet processing at the speed of the servers’ fastest cache(s), with zero inter-core communication. Metron also introduces a novel resource allocation scheme that minimizes the resource allocation overhead for large-scale NFV deployments. With commodity hardware assistance, Metron deeply inspects traffic at 40 Gbps and realizes stateful network functions at the speed of a 100 GbE network card on a single server. Metron has 2.75-6.5x better efficiency than OpenBox, a state of the art NFV system, while ensuring key requirements such as elasticity, fine-grained load balancing, and flexible traffic steering., Time-Critical Clouds, WASP
- Published
- 2018
19. Metron: NFV service chains at the true speed of the underlying hardware
- Author
-
UCL - SST/ICTM/INGI - Pôle en ingénierie informatique, Katsikas, Georgios P., Barbette, Tom, Kostic, Dejan, Rebecca, Steinert, Maguire Jr., Gerald Q., UCL - SST/ICTM/INGI - Pôle en ingénierie informatique, Katsikas, Georgios P., Barbette, Tom, Kostic, Dejan, Rebecca, Steinert, and Maguire Jr., Gerald Q.
- Abstract
In this paper we present Metron, a Network Functions Virtualization (NFV) platform that achieves high resource utilization by jointly exploiting the underlying network and commodity servers’ resources. This synergy allows Metron to: (i) offload part of the packet processing logic to the network, (ii) use smart tagging to setup and exploit the affinity of traffic classes, and (iii) use tag-based hardware dispatching to carry out the remaining packet processing at the speed of the servers’ fastest cache(s), with zero inter-core communication. Metron also introduces a novel resource allocation scheme that minimizes the resource allocation overhead for large-scale NFV deployments. With commodity hardware assistance, Metron deeply inspects traffic at 40 Gbps and realizes stateful network functions at the speed of a 100 GbE network card on a single server. Metron has 2.75-6.5x better efficiency than OpenBox, a state of the art NFV system, while ensuring key requirements such as elasticity, fine-grained load balancing, and flexible traffic steering.
- Published
- 2018
20. Realizing High Performance NFV Service Chains
- Author
-
Katsikas, Georgios P.
- Subjects
profiler ,multiplexing ,synthesis ,service kedjor ,Communication Systems ,planläggningsstrategier ,profilering ,service chains ,NFV ,Datorsystem ,syntetiserade ,line-rate ,Computer Systems ,scheduling ,40 Gbps ,Kommunikationssystem - Abstract
Network functions (NFs) hold a key role in networks, offering in-network services, such as enhanced performance, policy enforcement, and security. Traditionally, NFs have been implemented in specialized, thus expensive hardware. To lower the costs of deploying NFs, network operators have adopted network functions virtualization (NFV), by migrating NFs from hardware to software running in commodity servers. Several approaches to NFV have shown that commodity network stacks and drivers (e.g., Linux-based) struggle to keep up with increasing hardware speed. Despite this, popular networking services still rely on these commodity components. Moreover, chaining NFs (also known as service chaining) is challenging due to redundancy in the elements of the chain. This licentiate thesis addresses the performance problems of NFV service chains.The first contribution is a framework that (i) profiles NFV service chains to uncover performance degradation reasons and (ii) leverages the profiler’s data to accelerate these chains, by combining multiplexing of system calls with scheduling strategies. These accelerations improve the cache utilization and thereby the end-to-end latency of chained NFs is reduced by a factor of three. Moreover, the same chains experience a multi-fold latency variance reduction; this result improves the quality of highly-interactive services.The second contribution of this thesis substantially revises the way NFV service chains are realized. NFV service chains are synthesized while eliminating redundant input/output and repeated elements, providing consolidated stateful cross layer packet operations across the chain. This software-based synthesis achieves line-rate 40 Gbps throughput for stateful and long service chains. This performance is 8.5x higher than the performance achieved by the software-based state of the art FastClick framework. Experiments with three example Internet Service Provider-level service chains show that this synthesis approach operates at 40 Gbps, when the classification of these chains is offloaded to an OpenFlow switch. Nätverksfunktioner (NF) har en nyckelroll i nätverk. De erbjuder tjänster i nätverken som förbättrad prestanda, policy övervakning och säkerhetsfunktioner. Vanligtvis så har NF implementerats med hjälp av specialiserad, och därmed kostsam, hårdvara. Detta har lett till att nätverksoperatörer har börjat använda nätverksfunktionsvirtualisering (NFV) för att minska kostnaden. NFV implementeras genom att NF flyttas från specialiserad hårdvara till mjukvara som kör på vanliga servrar. Flera försök med NFV har visat att vanliga nätverksstackar och drivrutiner (exempelvis Linux baserade) har svårt att erbjuda samma prestanda som hårdvaran gör. Trots detta bygger flera populära nätverkstjänster på NFV. Dessutom är det en utmaning att koppla samman NFV i kedjor, då redundanta operationer utförs. I den här avhandlingen försöker vi lösa prestanda problem kopplade till kedjor av NFV. Det första bidraget i den här avhandlingen är ett ramverk som (i) profilerar NFV kedjor för att hitta orsaker till prestanda problem samt (ii) använder profileringsdata för att förbättra prestandan i kedjorna. Detta görs genom att kombinera multiplexing av systemanrop med planläggningsstrategier. Tillsammans förbättrar dessa lösningar cache användningen och minskar därmed end-to-end latensen i kedjade NFV med en faktor tre. Dessutom minskar vår metod variansen i latens, något som är viktigt för tjänstekvalitén i interaktiva tjänster.Det andra bidraget i den här avhandlingen är en omarbetning av hur kedjade NFV konstrueras. Vi syntetiserar NFV service kedjor genom att ta bort redundanta element och konsoliderar paketoperationer som sträcker sig över flera lager i nätverksstacken. Vår mjukvarubaserade lösning klarar av 40 Gbps genomströmning i en lång kedja. Detta är 8.5 ggr mer än vad som uppnåtts med den tidigare standard lösningen för mjukvara, ramverket FastClick. Vi presenterar experiment med tre servicekedjor för nätverksleverantörer där vår syntetiserade lösning klarar 40 Gbps, när klassificeringen av kedjan görs med hjälp av en OpenFlow switch. QC 20161103 European Union Horizon 2020 BEhavioural BAsed forwarding (BEBA) European Research Council (ERC) PROPHET
- Published
- 2016
21. SNF: synthesizing high performance NFV service chains
- Author
-
Katsikas, Georgios P., Enguehard, Marcel, Kuźniar, Maciej, Maguire Jr, Gerald Q., Kostic, Dejan, Katsikas, Georgios P., Enguehard, Marcel, Kuźniar, Maciej, Maguire Jr, Gerald Q., and Kostic, Dejan
- Abstract
In this paper we introduce SNF, a framework that synthesizes (S) network function (NF) service chains by eliminating redundant I/O and repeated elements, while consolidating stateful cross layer packet operations across the chain. SNF uses graph composition and set theory to determine traffic classes handled by a service chain composed of multiple elements. It then synthesizes each traffic class using a minimal set of new elements that apply single-read-single-write and early-discard operations. Our SNF prototype takes a baseline state of the art network functions virtualization (NFV) framework to the level of performance required for practical NFV service deployments. Software-based SNF realizes long (up to 10 NFs) and stateful service chains that achieve line-rate 40 Gbps throughput (up to 8.5x greater than the baseline NFV framework). Hardware-assisted SNF, using a commodity OpenFlow switch, shows that our approach scales at 40 Gbps for Internet Service Provider-level NFV deployments., QC 20170626, European Union Horizon 2020 BEhavioural BAsed forwarding (BEBA), European Research Council (ERC) PROPHET
- Published
- 2016
- Full Text
- View/download PDF
22. SNF: synthesizing high performance NFV service chains
- Author
-
Katsikas, Georgios P., primary, Enguehard, Marcel, additional, Kuźniar, Maciej, additional, Maguire Jr, Gerald Q., additional, and Kostić, Dejan, additional
- Published
- 2016
- Full Text
- View/download PDF
23. SNF: Synthesizing high performance NFV service chains
- Author
-
Katsikas, Georgios P, primary, Enguehard, Marcel, additional, Kuźniar, Maciej, additional, Maguire Jr., Gerald Q, additional, and Kostić, Dejan, additional
- Published
- 2016
- Full Text
- View/download PDF
24. Low disease activity—irrespective of serologic status at baseline—associated with reduction of corticosteroid dose and number of flares in patients with systemic lupus erythematosus treated with belimumab: A real-life observational study.
- Author
-
Fanouriakis, Antonis, Adamichou, Christina, Koutsoviti, Sofia, Panopoulos, Stylianos, Staveri, Chrysanthi, Klagou, Anastasia, Tsalapaki, Christina, Pantazi, Lamprini, Konsta, Styliani, Mavragani, Clio P., Dimopoulou, Despoina, Ntali, Styliani, Katsikas, Georgios, Boki, Kyriaki A., Vassilopoulos, Dimitrios, Konstantopoulou, Pinelopi, Liossis, Stamatis-Nick, Elezoglou, Antonia, Tektonidou, Maria, and Sidiropoulos, Prodromos
- Abstract
Abstract Background Low disease activity is a validated target of current systemic lupus erythematosus (SLE) therapy. The aim of this study was to assess the ability of belimumab to achieve low disease activity states in real-life settings. Methods Multicentre prospective observational study of consecutive SLE patients receiving belimumab for at least 3 months, due to active disease refractory to at least one conventional immunosuppressant. Disease activity, including the recently defined lupus low disease activity state (LLDAS) and remission (clinical SLEDAI-2K = 0), accrual of organ damage, flares and side effects were documented. Results Ninety-one patients were included [94.5% women, mean (SD) age 45.9 (12.5) years]. Most frequent manifestations were arthritis (76.7%), rash (72.5%), serologic activity (low C3/C4 and/or high anti-dsDNA; 54.9%), hair loss (47.2%) and mucosal ulcers (27.5%). Median (range) duration of treatment was 10.5 (3.0–42.1) months. Belimumab significantly decreased average SLEDAI-2K, physician global assessment (PGA) and daily prednisone dose over time, as early as 3 months after initiation, with over 20% of patients discontinuing corticosteroids. Although reduction in clinical (i.e., excluding serology) SLEDAI-2K was more pronounced in patients who were serologically active (from 8 to 1.5 at 12 months) as compared to serologically inactive (from 6 to 4) at baseline, attainment of LLDAS did not differ between the two groups and was reached by more than 40% of completer patients after 9–12 months. In addition, the number of flares and severe flares was reduced by 62% and 50%, respectively, during the first 12 months of treatment. Twenty patients (22.0%) discontinued treatment due to inadequate response and two due to side effects potentially related to the drug. Conclusions In real-life, belimumab is efficacious in achieving low disease activity in over 40% of unselected patients, in combination with reduction of corticosteroid dosage and number of flares. Both serologically active and inactive patients respond to the drug. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
25. Secondary Cutaneous Nodular AA Amyloidosis in a Patient With Primary Sjögren Syndrome and Celiac Disease
- Author
-
Katsikas, Georgios A., Maragou, Maria, Rontogianni, Demetra, Gouma, Paraskevi, Koutsouvelis, Ioannis, and Kappou-Rigatou, Iris
- Abstract
We describe a 62-year-old female with primary Sjögren syndrome and myopathy, severe osteoporosis, and vertebral fractures that were attributed to celiac disease. A year after the diagnosis, she developed a skin nodule on the extensor surface of her right elbow, which was due to an amyloid deposit of AA type. Amyloidosis, although relatively common in some chronic inflammatory diseases, has been uncommon in Sjögren syndrome or celiac disease. Visceral amyloid was not found in this patient.
- Published
- 2008
- Full Text
- View/download PDF
26. RSS++
- Author
-
Barbette, Tom, Katsikas, Georgios P., Maguire, Gerald Q., and Kostić, Dejan
- Full Text
- View/download PDF
27. Rituximab therapy reduces activated B cells in both the peripheral blood and bone marrow of patients with rheumatoid arthritis: depletion of memory B cells correlates with clinical response
- Author
-
Nakou, Magda, Katsikas, Georgios, Sidiropoulos, Prodromos, Bertsias, George, Papadimitraki, Eva, Raptopoulou, Amalia, Koutala, Helen, Papadaki, Helen, Kritikos, Herakles, and Boumpas, Dimitrios
- Abstract
Bone marrow (BM) is an immunologically privileged site where activated autoantibody-producing B cells may survive for prolonged periods. We investigated the effect of rituximab (anti-CD20 mAb) in peripheral blood (PB) and BM B-cell and T-cell populations in active rheumatoid arthritis (RA) patients.
- Published
- 2009
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.