Alberto García-Martínez

Universidad Carlos III de Madrid

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Marcelo Bagnulo

Universidad Carlos III de Madrid

Arturo Azcorra

Universidad Carlos III de Madrid

ÁV

Á. Viña

Universidade da Coruña

Juan A. Carral

Universidad de Alcalá

Guillermo Ibáñez

Universidad de Alcalá

Stefano Angieri

Universidad Carlos III de Madrid

Kshitiz Verma

Indian Institute of Technology Guwahati

José M. Arco

Universidad de Alcalá

Bingyang Liu

Huawei Technologies (China)

Ignacio Soto

Universidad Politécnica de Madrid

Cooperative Institutions

Universidad Carlos III de Madrid

Universidad Politécnica de Madrid

IMDEA Networks

Universidad de Alcalá

Instituto de Salud Carlos III

Central University Hospital of Asturias

UCLouvain

Instituto de Investigación Sanitaria del Principado de Asturias

Universidad Complutense de Madrid

University of Namur

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Efficient security for IPv6 multihoming

ACM SIGCOMM Computer Communication Review (2005)

Marcelo Bagnulo Alberto García-Martínez Arturo Azcorra

In this note, we propose a security mechanism for protecting IPv6 networks from possible abuses caused by the malicious usage of a multihoming protocol. In the presented approach, each multihomed node is assigned multiple prefixes from its upstream providers, and it creates the interface identifier part of its addresses by incorporating a cryptographic one-way hash of the available prefix set. The result is that the addresses of each multihomed node form an unalterable set of intrinsically bound IPv6 addresses. This allows any node that is communicating with the multihomed node to securely verify that all the alternative addresses proposed through the multihoming protocol are associated to the address used for establishing the communication. The verification process is extremely efficient because it only involves hash operations.

Multihoming

Prefix

IPv6 address

10.1145/1064413.1064420

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Citations (16)

Prevalencia, tipo de epilepsia y uso de fármacos antiepilépticos en atención primaria

Revista de Neurología (2015)

Elena Fernández-Suárez Rubén Villa-Estébanez Alberto García-Martínez José A Fidalgo-González Ahmad Amer Zanabili Al-Sibbai

Epilepsy is a disease with great social and economic impact. The prevalence should be used as the most important basis for planning the secondary and tertiary prevention.To identify patients with a diagnosis of epilepsy in a primary care center and determine the prevalence, demographic characteristics, type of epileptic syndrome and the use of antiepileptic drugs.Retrospective cross-sectional descriptive study. Included 196 patients with a diagnosis of epilepsy belonging to a primary care center and review the medical history, studying socio-demographic variables and clinical-pharmacological.The prevalence of epilepsy: 8.4/1000 inhabitants. Mean age: 50.3 years. Sex: 52.6% men.79.6% urban. Family history of epilepsy: 14.8%. Type of epilepsy: symptomatic focal stroke (14.3%), idiopathic generalized (13.8%), focal cryptogenic (8.7%), not classified (31.1%). Average age at the beginning of seizures: 31.6 years. Neurological and/or psychiatric comorbidity: 62.8%. Last follow-up: 18.9% without antiepileptic treatment, 56.6% monotherapy and 24.5% polytherapy. Seizure-free: 76.5%. Drugs most frequently prescribed: valproic acid, carbamazepine, phenytoin, lamotrigine, levetiracetam. 78.6% without side effects. Exitus: 4.1%.The prevalence of patients with epilepsy was 8.4/1000 inhabitants, most frequent etiology the symptomatic focal stroke. More than half of patients suffered neurological and/or psychiatric comorbidity. At the end of follow-up the great majority were seizure-free without adverse effects of the antiepileptic drug treatment.Prevalencia, tipo de epilepsia y uso de farmacos antiepilepticos en atencion primaria.Introduccion. La epilepsia es una enfermedad con gran repercusion social y economica. La prevalencia deberia ser usada como la base mas importante para planificar la prevencion secundaria y terciaria. Objetivos. Identificar los pacientes con diagnostico de epilepsia en un centro de atencion primaria y determinar la prevalencia, las caracteristicas demograficas, el tipo de sindrome epileptico y el uso de los farmacos antiepilepticos. Pacientes y metodos. Estudio descriptivo transversal retrospectivo. Incluyo 196 pacientes con diagnostico de epilepsia pertenecientes a un centro de salud y revision de la historia clinica hospitalaria, con el estudio de las variables sociodemograficas y clinicofarmacologicas. Resultados. Prevalencia de epilepsia: 8,4/1.000 habitantes. Edad media: 50,3 años. Sexo: 52,6%, hombres. Ambito: 79,6%, urbano. Antecedentes familiares de epilepsia: 14,8%. Tipo de epilepsia: focal sintomatica por ictus (14,3%), generalizada idiopatica (13,8%), focal criptogenica (8,7%), no clasificada (31,1%). Edad media al inicio de la crisis: 31,6 años. Comorbilidad neurologica o psiquiatrica: 62,8%. Ultima revision: el 18,9% sin tratamiento antiepileptico, el 56,6% en monoterapia y el 24,5% en politerapia. Libres de crisis: 76,5%. Farmacos mas prescritos: acido valproico, carbamacepina, fenitoina, lamotrigina y levetiracetam. Un 78,6% sin efectos secundarios. Fallecimiento: 4,1%. Conclusiones. La prevalencia de pacientes con epilepsia fue de 8,4/1.000 habitantes y predomina la focal sintomatica por ictus. Casi un tercio de los pacientes referia algun factor desencadenante de crisis, principalmente consumo de alcohol o fiebre. Predomina la monoterapia, los efectos secundarios son escasos y, en la ultima revision, la mayoria se hallaba libre de crisis.

Levetiracetam

Etiology

Stroke

10.33588/rn.6012.2015038

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Citations (11)

Designing Low Cost and Energy Efficient Access Network for the Developing World.

arXiv (Cornell University) (2015)

Kshitiz Verma Shmuel Zaks Alberto García-Martínez

Internet is growing rapidly in the developing world now. Our survey of four networks in India, all having at least one thousand users, suggest that both installation cost and recurring cost due to power consumption pose a challenge in its deployment in developing countries. In this paper, we first model the access design problem by dividing the users in two types 1) those that may access the network anytime and 2) those who need it only during office hours on working days. The problem is formulated as a binary integer linear program which turns out to be NP-hard. We then give a distributed heuristic for network design. We evaluate our model and heuristic using real data collected from IIT Kanpur LAN for more than 50 days. Results show that even in a tree topology -- which is a common characteristic of all networks who participated in our study, our design can reduce the energy consumption of the network by up to 11% in residential-cum-office environments and up to 22% in office-only environments in comparison with current methods without giving up on the performance. The extra cost incurred due to our design can be compensated in less than an year by saving in electricity bill of the network.

Meta heuristic

Consumption

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An experimental evaluation of LEDBAT++

Computer Networks (2022)

Marcelo Bagnulo Alberto García-Martínez

LEDBAT++ is the evolution of LEDBAT, a congestion control algorithm originally designed to provide less-than-best-effort transport on the Internet. LEDBAT++ aims to address a number of shortcomings present in LEDBAT, including late-comer advantage, latency drift, competition on equal grounds with best effort traffic in the presence of small buffers and difficulties experienced while measuring the variations on the delay. In this paper, we perform an experimental evaluation of LEDBAT++ using the Windows Server's LEDBAT++ implementation. We find that while LEDBAT++ overcomes all the limitations identified in LEDBAT, the change introduced in LEDBAT++ to do so results in a performance penalty that prevents LEDBAT++ flows to seize all the available capacity when there is no competing traffic. We propose two simple modifications to the LEDBAT++ algorithm that would address the identified issues and reduce the penalty.

10.1016/j.comnet.2022.109036

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Design, implementation and validation of a receiver-driven less-than-best-effort transport

Computer Networks (2023)

Marcelo Bagnulo Alberto García-Martínez Anna Maria Mandalari Praveen Balasubramanian Daniel Havey

LEDBAT++ is a congestion-control algorithm that implements a less-than-best-effort transport service. In this paper we present rLEDBAT, a purely receiver-based mechanism to implement LEDBAT++ for TCP. rLEDBAT enables a receiver to select some incoming traffic as less-than-best-effort, managing the capacity of the downlink. We describe the different mechanisms composing rLEDBAT that enable the execution of the LEDBAT++ congestion control algorithm at the receiver. We have implemented and experimentally tested rLEDBAT. We validate that the mechanisms incorporated by rLEDBAT at the receiver are indeed effective to implement a less-than-best-effort transport service at the receiver, as it performs similarly to the original sender-based LEDBAT++.

Communication source

10.1016/j.comnet.2023.109841

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BGP-like TE Capabilities for SHIM6

Marcelo Bagnulo Alberto García-Martínez Arturo Azcorra

In this paper we present a comprehensive set of mechanisms that restore to the site administrator the capacity of enforcing traffic engineering (TE) policies in a multiaddressed IPv6 scenario. The mechanisms rely on the ability of SHIM6 to securely perform locator changes in a transparent fashion to transport and application layers. Once an outgoing path has been selected for a communication by proper routing configuration in the site, the source prefix of SHIM6 data packets is rewritten by the site routers to avoid packet discarding due to ingress filtering. The SHIM6 locator preferences exchanged in the context establishment phase are modified by the site routers to influence in the path used for receiving traffic. Scalable deployment is ensured by the stateless nature of these mechanisms

Source routing

Prefix

10.1109/euromicro.2006.25

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Citations (2)

An Integrated Approach to Prevent Address Spoofing in IPv6 Links

IEEE Communications Letters (2012)

Alberto García-Martínez Marcelo Bagnulo

We propose an integrated approach to protect from address spoofing for both IPv6 and Layer-2 addresses, and from address resolution attacks. The proposed approach is an extension to the FCFS SAVI specification, and relies on the inspection and generation of standard Neighbor Solicitation messages. It does not require host modification and manual configuration is only needed to indicate the ports to which routers connect.

Spoofing attack

ARP spoofing

IP address spoofing

IPv6 address

10.1109/lcomm.2012.100812.121517

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Citations (6)

rLEDBAT: receiver-driven Low Extra Delay Background Transport for TCP

Marcelo Bagnulo Gabriel Montenegro Alberto García-Martínez Praveen Balasubramanian

This document specifies the rLEDBAT, a set of mechanisms that enable the execution of a less-than-best-effort congestion control algorithm for TCP at the receiver end.

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SLEEPWELL: Energy Efficient Network Design for the Developing World Using Green Switches

Kshitiz Verma Shmuel Zaks Alberto García-Martínez

Internet is growing rapidly in the developing world now. Stringent budget constraints give rise to networks with tree topology, leaving lesser room to apply energy savings methods proposed in the last decade as there are no redundant links or nodes in the network. In this paper, we propose SLEEPWELL, design of energy efficient network topology using energy aware networking devices. We divide users according to their profile of network usage and users with similar profile are all connected to one switch to allow the switch to sleep. We evaluate our framework using real data collected from the Local Area Network of IIT Kanpur (an Indian university) having more than ten thousand network users. Results show that even in a tree topology, SLEEPWELL achieves substantial energy gains, up to 22% using energy-efficient hardware, without compromising performance. We also show that dividing users in just two profiles accounts for more than 90% of the total energy saved using SLEEPWELL. We also evaluate the overheads occurred and show that the extra cost incurred can be recovered within two years for most of the practical scenarios.

Tree (set theory)

10.1109/aina.2016.98

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Hierarchical Up/Down routing architecture for ethernet backbones and campus networks

Guillermo Ibáñez Alberto García-Martínez Juan A. Carral Pedro A. González Arturo Azcorra

We describe a new layer two distributed and scalable routing architecture. It uses an automatic hierarchical node identifier assignment mechanism associated to the rapid spanning tree protocol. Enhanced up/down mechanisms are used to prohibit some turns at nodes to break cycles, instead of blocking links like the spannning tree protocol does. The protocol performance is similar or better than other turn prohibition algorithms recently proposed with lower complexity O(Nd) and better scalability. Simulations show that the fraction of prohibited turns over random networks is less than 0.2. The effect of root bridge election on the performance of the protocol is limited both in the random and regular networks studied. The use of hierarchical, tree-descriptive addresses simplifies the routing, and avoids the need of all nodes having a global knowleddge of the network topology. Routing frames through the hierarchical tree at very high speed is possible by progressive decoding of frame destination address, without routing tables or port address learning. Coexistence with standard bridges is achieved using combined devices: bridges that forward the frames having global destination MAC addresses as standard bridges and frames with local MAC frames with the proposed protocol.

Hierarchical routing

Zone Routing Protocol

Subnetwork

10.1109/infocom.2008.4544622

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Citations (4)