Santiago Garcia-Jimenez

Overlap Indices: Construction of and Application to Interpolative Fuzzy Systems

In this paper, we analyze the minimal set of axioms that overlap indices between fuzzy sets must fulfill. We also present a method to build overlap indices using overlap functions, and we carry on a theoretical study about the continuity, the invariance, and some general properties of such indices. We present a generalization of the inference algorithm for interpolative fuzzy systems using overlap indices. We also propose an algorithm for choosing, among a set of overlap indices, the best one for a considered problem.

Techniques for better alias resolution in Internet topology discovery

One of the challenging problems related with network topology discovery in Internet is the process of IP address alias identification. Topology information is usually obtained from a set of traceroutes that provide IP addresses of routers in the path from a source to a destination. If these traceroutes are repeated between several source/destination pairs we can get a sampling of all IP addresses for crossed routers. In order to generate the topology graph in which each router is a node, it is needed to identify all IP addresses that belong to the same router. In this work we propose improvements over existing methods to obtain alias identification related mainly with the types and options in probing packets.

ETOMIC Advanced Network Monitoring System for Future Internet Experimentation

ETOMIC is a network traffic measurement platform with high precision GPS-synchronized monitoring nodes. The infrastructure is publicly available to the network research community, supporting advanced experimental techniques by providing high precision hardware equipments and a Central Management System. Researchers can deploy their own active measurement codes to perform experiments on the public Internet. Recently, the functionalities of the original system were significantly extended and new generation measurement nodes were deployed. The system now also includes well structured data repositories to archive and share raw and evaluated data. These features make ETOMIC as one of the experimental facilities that support the design, development and validation of novel experimental techniques for the future Internet. In this paper we focus on the improved capabilities of the management system, the recent extensions of the node architecture and the accompanying database solutions.

Pamplona-traceroute: Topology discovery and alias resolution to build router level Internet maps

An Internet topology map at the router level not only needs to discover IP addresses in Internet paths (traceroute) but also needs to identify IP addresses belonging to the same router (IP aliases). Both processes, discovery and IP alias resolution, have traditionally been independent tasks. In this paper, a new tool called Pamplona-traceroute is proposed to improve upon current results in a state of the art for Internet topology construction at the router level. Indirect probing using TTL-scoped UDP packets, usually present in the discovery phases, is reused in IP alias resolution phases, providing high identification rates, especially in access routers.

Validity of router responses for IP aliases resolution

In order to obtain close-to-reality Internet maps, IP aliases resolution allows identifying IP addresses belonging to the same router. Mainly, active probing is used for IP aliases resolution following direct and indirect schemes. Also, different types of probe packets are used (ICMP, UDP, etc.) focusing on different header fields and characteristics of IP and higher layers. Responsiveness of routers is different not only in the number of response packets received, but also in the validity of those packets to be used in IP aliases identification. Therefore, specific behavior of routers generating those response packets can decide the success or failure of specific IP aliases resolution methods. In this paper, an in-depth analysis of router behaviors is provided considering not only router responsiveness, but also the validity of those responses to be used in IP aliases resolution. Our results show that although responsiveness is better for indirect probing, direct probing with ICMP Echo probe packets and IPID-based behavior provide the best identification ratio for IP aliases resolution.

On the performance and improvement of alias resolution methods for Internet core networks

The Internet is a huge interconnection of thousands of networks with different technologies, equipment, configurations, and administrative owners. This, added to the lack of public information about those individual infrastructures, makes it a difficult task to provide a so-called Internet map: a topological map with information of routers, interconnections between routers, and IP addressing configuration. Traditional topology discovery methods based on traceroutes only provide IP addresses in the path between end-nodes. Some of those IP addresses can belong to the same router, and this identification is made by alias resolution methods. Therefore, alias resolution allows to provide router-level map of the Internet with important applications in network simulation, protocol design, network management, network security, network service design, and geolocation. In this paper, alias resolution methods are analyzed in Internet core networks (GlobalNOC, Canet4, and Geant). This allows to identify peculiar behaviors in these core networks, improving alias resolution methods. Simultaneously, reduction methods are used to decrease the number of probing packets in alias resolution methods.

IP addresses distribution in Internet and its application on reduction methods for IP alias resolution

Discovery of Internet topology is an important and open task. It is difficulted by the high number of networks and internetworking equipments, and even by the dynamic of those interconnections. Mapping Internet at router-level needs to identify IP addresses that belong to the same router. This is called IP address alias resolution and classical methods in the state of the art like Ally need to test IP addresses in pairs. This means a very high cost in traffic generated and time consumption, specially with an increasing topology size. Some methods have been proposed to reduce the number of pairs of IP addresses to compare based on the TTL or IP identifier fields from the IP header. However both need extra traffic and they have problems with the probing distribution between several probing nodes. This paper proposes to use the peculiar distribution of IP addresses in Internet autonomous systems in order to reduce the number of IP addresses to compare. The difference between pairs of IP addresses is used to know a priori if they are candidates to be alias with certain probability. Performance evaluation has been made using Planetlab and Etomic measurement platforms. The paper justifies the reduction method, obtaining high reduction ratios without injecting extra traffic in the network and with the possibility to distribute the process for alias resolution.

Forest fire detection

Graphical abstractDisplay Omitted HighlightsWe propose a new inference algorithm using overlap functions and indices.The convex combination of overlap expressions maintains the overlap properties.We avoid the difficult selection of appropriate expressions for each problem.We use our new inference algorithm in a Fuzzy Logic System to detect forest fire. It is well known that a powerful method to tackle diverse problems with lack of knowledge and/or uncertainty are Fuzzy Logic Systems (FLSs). In the literature, there exist different fuzzy inference mechanisms based on fuzzy variables and fuzzy rules to obtain a solution. In this work we introduce a generalization of the inference algorithm proposed by Mamdani, by using overlap functions and overlap indices. A challenging issue is the selection of most suitable overlap expressions for each problem. For this aim, we propose to use the convex combination of several ones. In this way, the conclusions obtained by our FLSs avoid the bad results obtained by an inadequate overlap expression. We test our proposal on a real problem of forest fire detection using a wireless sensor network.

TBDClust: Time-based density clustering to enable free browsing of sites in pay-per-use mobile Internet providers

Abstract The World Wide Web has evolved rapidly, incorporating new content types and becoming more dynamic. The contents from a website can be distributed between several servers, and as a consequence, web traffic has become increasingly complex. From a network traffic perspective, it can be difficult to ascertain which websites are being visited by a user, let alone which part of the users traffic each website is responsible for. In this paper we present a method for identifying the TCP connections involved in the same full webpage download without the need of deep packet inspection. This identification is needed for example to enable free browsing of specific websites in a pay per use mobile Internet access. It could be not only for third party promoted websites but also portals to gubernamental or medical emergency websites. The proposal is based on a modification of the DBSCAN clustering algorithm to work online and over one-dimensional sorted data. In order to validate our results we use both real traffic and packet captures from a controlled environment. The proposal achieves excellent results in consistency (99%) and completeness (92%), meaning that its error margin identifying the webpage downloads is minimal.

Probing Distribution in Time and Space for IP Alias Resolution

The Internet is composed of thousands of networks, interconnected to provide end-to-end IP (Internet Protocol) connectivity. However, Very little public information is provided about these networks and their interconnections. The information needed to create an Internet map of the routers and the links between those routers must be derived from techniques for discovering IP addresses (traceroute) and for associating IP addresses that belong to the same router (IP aliases). Both processes IP address discovery and IP alias resolution require a large measurement infrastructure, and they introduce variable amounts of traffic into the network. Although systematic proposals have been made for creating a scalable IP address discovery system, the equivalent system for resolving IP aliases is far from being determined. In this paper, new proposals for obtaining a scalable IP aliasing system are evaluated and compared with existing solutions. Distributing measurements along multiple vantage points (spatial distribution) and extending probing tasks over time (temporal distribution) have been identified as the key methods for reducing the overhead of IP alias resolution.