52 research outputs found
P2P overlay over Simctl
This project intends to find and implement a p2p overlay over the simctl platform. Simctl is used both for teaching and research in the network engineering department.P2P systems became an interesting area since early 2000. Researchers conducted a large amount of research in some challenging areas and, to check their experiments, several implementations and simulators were created. Over time, Internet has evolved and P2P has been widely used for file sharing, but the main structured P2P overlays were progressively abandoned. However, these overlays are still taught in network engineering courses. The aim of this master thesis is to find and implement a p2p overlay over the \texttt{simctl} platform, used both for teaching and research in the network engineering department. First, it is tried to locate and test the original structured P2P overlays source codes developed by the authors of the original publications. Then, several available P2P implementations developed by researchers and users have been tested. Once the software was selected, different scenarios for \texttt{simctl} were developed. Finally, a lab session was created by using the previous scenarios
Peer-to-peer-telefoni over Internett
Signaleringsprotokollen Session Initiation Protocol (SIP) er en veletablert standard for Voice over IP (VoIP), men det finnes også aktører i VoIP-industrien som ikke følger denne standarden. I folks dagligtale er telefoni over internett ofte synonymt med tjenesten «Skype». «Skype» har har klart å oppnå stor popularitet, og tilbyr en velfungerende VoIP-tjeneste som lar folk kommunisere med hverandre med både lyd, video og lynmeldinger. Mye av styrken i «Skype» ligger i at den er veldig lett å bruke, og at den er robust og skalerbar.
«Skype» har sitt opphav fra fildelingstjenesten «KaZaa», og er i
stor grad basert på Peer-to-Peer (P2P). Jeg vil derfor i denne oppgaven presentere hvordan vi kan kombinere signaleringsprotokollen SIP og P2P for å oppnå en robusthet og skalerbarhet slik som «Skype». Dette vil jeg vise ved å først gi en innføring i hvordan telefoni over internett fungerer, og deretter en innføring i P2P. Jeg vil også vise til den pågående standardiseringen av en ny signaleringsprotokoll som kombinerer P2P og SIP. I oppgaven vil jeg også presentere en prototype som kombinerer SIP og P2P
Efficient service discovery in wide area networks
Living in an increasingly networked world, with an abundant number
of services available to consumers, the consumer electronics market
is enjoying a boom. The average consumer in the developed world may
own several networked devices such as games consoles, mobile phones,
PDAs, laptops and desktops, wireless picture frames and printers to
name but a few. With this growing number of networked devices comes
a growing demand for services, defined here as functions requested
by a client and provided by a networked node. For example, a client
may wish to download and share music or pictures, find and use
printer services, or lookup information (e.g. train times, cinema
bookings).
It is notable that a significant proportion of networked devices are
now mobile. Mobile devices introduce a new dynamic to the service
discovery problem, such as lower battery and processing power and
more expensive bandwidth. Device owners expect to access services
not only in their immediate proximity, but further afield (e.g. in
their homes and offices). Solving these problems is the focus of
this research.
This Thesis offers two alternative approaches to service discovery
in Wide Area Networks (WANs). Firstly, a unique combination of the
Session Initiation Protocol (SIP) and the OSGi middleware technology
is presented to provide both mobility and service discovery
capability in WANs. Through experimentation, this technique is shown
to be successful where the number of operating domains is small, but
it does not scale well.
To address the issue of scalability, this Thesis proposes the use of
Peer-to-Peer (P2P) service overlays as a medium for service
discovery in WANs. To confirm that P2P overlays can in fact support
service discovery, a technique to utilise the Distributed Hash Table
(DHT) functionality of distributed systems is used to store and
retrieve service advertisements. Through simulation, this is shown
to be both a scalable and a flexible service discovery technique.
However, the problems associated with P2P networks with respect to
efficiency are well documented.
In a novel approach to reduce messaging costs in P2P networks,
multi-destination multicast is used. Two well known P2P overlays are
extended using the Explicit Multi-Unicast (XCAST) protocol. The
resulting analysis of this extension provides a strong argument for
multiple P2P maintenance algorithms co-existing in a single P2P
overlay to provide adaptable performance. A novel multi-tier P2P
overlay system is presented, which is tailored for service rich
mobile devices and which provides an efficient platform for service
discovery
Parallelisation for data-intensive applications over peer-to-peer networks
In Data Intensive Computing, properties of the data that are the input for
an application decide running performance in most cases. Those properties include
the size of the data, the relationships inside data, and so forth. There is a
class of data intensive applications (BLAST, SETI@home, Folding@Home and
so on so forth) whose performances solely depend on the amount of input data.
Another important characteristic of those applications is that the input data can be
split into units and these units are not related to each other during the runs of the
applications. This characteristic helps this class of data intensive applications to
be parallelised in the way where the input data is split into units and application
runs on different computer nodes for certain portion of the units. SETI@home and
Folding@Home have been successfully parallelised over peer-to-peer networks.
However, they suffer from the problems of single point of failure and poor scalability.
In order to solve these problems, we choose BLAST as our example data
intensive applications and parallelise BLAST over a fully distributed peer-to-peer
network.
BLAST is a popular bioinformatics toolset which can be used to compare
two DNA sequences. The major usage of BLAST is searching a query of sequences
inside a database for their similarities so as to identify whether they are
new. When comparing single pair of sequences, BLAST is efficient. However,
due to growing size of the databases, executing BLAST jobs locally produces
prohibitively poor performance. Thus, methods for parallelising BLAST are
sought.
Traditional BLAST parallelisation approaches are all based on clusters.
Clusters employ a number of computing nodes and high bandwidth interlinks between
nodes. Cluster-based BLAST exhibits higher performance; nevertheless,
clusters suffer from limited resources and scalability problems. Clusters are expensive, prohibitively so when the growth of the sequence database are taken into
account. It involves high cost and complication when increasing the number of
nodes to adapt to the growth of BLAST databases. Hence a Peer-to-Peer-based
BLAST service is required.
This thesis demonstrates our parallelisation of BLAST over Peer-to-Peer
networks (termed ppBLAST), which utilises the free storage and computing resources
in the Peer-to-Peer networks to complete BLAST jobs in parallel. In order
to achieve the goal, we build three layers in ppBLAST each of which is responsible
for particular functions. The bottom layer is a DHT infrastructure with the
support of range queries. It provides efficient range-based lookup service and
storage for BLAST tasks. The middle layer is the BitTorrent-based database distribution.
The upper layer is the core of ppBLAST which schedules and dispatches
task to peers. For each layer, we conduct comprehensive research and the
achievements are presented in this thesis.
For the DHT layer, we design and implement our DAST-DHT. We analyse
balancing, maximum number of children and the accuracy of the range query.
We also compare the DAST with other range query methodology and state that if
the number of children is adjusted to more two, the performance of DAST overcomes
others. For the BitTorrent-like database distribution layer, we investigate
the relationship between the seeding strategies and the selfish leechers (freeriders
and exploiters). We conclude that OSS works better than TSS in a normal situation
Storing and managing data in a distributed hash table
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 83-90).Distributed hash tables (DHTs) have been proposed as a generic, robust storage infrastructure for simplifying the construction of large-scale, wide-area applications. For example, UsenetDHT is a new design for Usenet News developed in this thesis that uses a DHT to cooperatively deliver Usenet articles: the DHT allows a set of N hosts to share storage of Usenet articles, reducing their combined storage requirements by a factor of O(N). Usenet generates a continuous stream of writes that exceeds 1 Tbyte/day in volume, comprising over ten million writes. Supporting this and the associated read workload requires a DHT engineered for durability and efficiency. Recovering from network and machine failures efficiently poses a challenge for DHT replication maintenance algorithms that provide durability. To avoid losing the last replica, replica maintenance must create additional replicas when failures are detected. However, creating replicas after every failure stresses network and storage resources unnecessarily. Tracking the location of every replica of every object would allow a replica maintenance algorithm to create replicas only when necessary, but when storing terabytes of data, such tracking is difficult to perform accurately and efficiently. This thesis describes a new algorithm, Passing Tone, that maintains durability efficiently, in a completely decentralized manner, despite transient and permanent failures. Passing Tone nodes make replication decisions with just basic DHT routing state, without maintaining state about the number or location of extant replicas and without responding to every transient failure with a new replica. Passing Tone is implemented in a revised version of DHash, optimized for both disk and network performance.(cont.) A sample 12 node deployment of Passing Tone and UsenetDHT supports a partial Usenet feed of 2.5 Mbyte/s (processing over 80 Tbyte of data per year), while providing 30 Mbyte/s of read throughput, limited currently by disk seeks. This deployment is the first public DHT to store terabytes of data. These results indicate that DHT-based designs can successfully simplify the construction of large-scale, wide-area systems.by Emil Sit.Ph.D
Parallelisation for data-intensive applications over peer-to-peer networks
In Data Intensive Computing, properties of the data that are the input for an application decide running performance in most cases. Those properties include the size of the data, the relationships inside data, and so forth. There is a class of data intensive applications (BLAST, SETI@home, Folding@Home and so on so forth) whose performances solely depend on the amount of input data. Another important characteristic of those applications is that the input data can be split into units and these units are not related to each other during the runs of the applications. This characteristic helps this class of data intensive applications to be parallelised in the way where the input data is split into units and application runs on different computer nodes for certain portion of the units. SETI@home and Folding@Home have been successfully parallelised over peer-to-peer networks. However, they suffer from the problems of single point of failure and poor scalability. In order to solve these problems, we choose BLAST as our example data intensive applications and parallelise BLAST over a fully distributed peer-to-peer network. BLAST is a popular bioinformatics toolset which can be used to compare two DNA sequences. The major usage of BLAST is searching a query of sequences inside a database for their similarities so as to identify whether they are new. When comparing single pair of sequences, BLAST is efficient. However, due to growing size of the databases, executing BLAST jobs locally produces prohibitively poor performance. Thus, methods for parallelising BLAST are sought. Traditional BLAST parallelisation approaches are all based on clusters. Clusters employ a number of computing nodes and high bandwidth interlinks between nodes. Cluster-based BLAST exhibits higher performance; nevertheless, clusters suffer from limited resources and scalability problems. Clusters are expensive, prohibitively so when the growth of the sequence database are taken into account. It involves high cost and complication when increasing the number of nodes to adapt to the growth of BLAST databases. Hence a Peer-to-Peer-based BLAST service is required. This thesis demonstrates our parallelisation of BLAST over Peer-to-Peer networks (termed ppBLAST), which utilises the free storage and computing resources in the Peer-to-Peer networks to complete BLAST jobs in parallel. In order to achieve the goal, we build three layers in ppBLAST each of which is responsible for particular functions. The bottom layer is a DHT infrastructure with the support of range queries. It provides efficient range-based lookup service and storage for BLAST tasks. The middle layer is the BitTorrent-based database distribution. The upper layer is the core of ppBLAST which schedules and dispatches task to peers. For each layer, we conduct comprehensive research and the achievements are presented in this thesis. For the DHT layer, we design and implement our DAST-DHT. We analyse balancing, maximum number of children and the accuracy of the range query. We also compare the DAST with other range query methodology and state that if the number of children is adjusted to more two, the performance of DAST overcomes others. For the BitTorrent-like database distribution layer, we investigate the relationship between the seeding strategies and the selfish leechers (freeriders and exploiters). We conclude that OSS works better than TSS in a normal situation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Secure Connectivity With Persistent Identities
In the current Internet the Internet Protocol address is burdened with two roles. It serves as the identifier and the locator for the host. As the host moves its identity changes with its locator. The research community thinks that the Future Internet will include identifier-locator split in some form. Identifier-locator split is seen as the solution to multiple problems. However, identifier-locator split introduces multiple new problems to the Internet.
In this dissertation we concentrate on: the feasibility of using identifier-locator split with legacy applications, securing the resolution steps, using the persistent identity for access control, improving mobility in environments using multiple address families and so improving the disruption tolerance for connectivity.
The proposed methods achieve theoretical and practical improvements over the earlier state of the art. To raise the overall awareness, our results have been published in interdisciplinary forums.Nykypäivän Internetissä IP-osoite on kuormitettu kahdella eri roolilla. IP toimii päätelaitteen osoitteena, mutta myös usein sen identiteetinä. Tällöin laitteen identiteetti muuttuu laitteen liikkuessa, koska laitteen osoite vaihtuu. Tutkimusyhteisön mielestä paikan ja identiteetin erottaminen on välttämätöntä tulevaisuuden Internetissä. Paikan ja identiteetin erottaminen tuo kuitenkin esiin joukon uusia ongelmia.
Tässä väitöskirjassa keskitytään selvittämään paikan ja identiteetin erottamisen vaikutusta olemassa oleviin verkkoa käyttäviin sovelluksiin, turvaamaan nimien muuntaminen osoitteiksi, helpottamaan pitkäikäisten identiteettien käyttöä pääsyvalvonnassa ja parantamaan yhteyksien mahdollisuuksia selviytyä liikkumisesta usean osoiteperheen ympäristöissä.
Väitöskirjassa ehdotetut menetelmät saavuttavat sekä teoreettisia että käytännön etuja verrattuna aiempiin kirjallisuudessa esitettyihin menetelmiin. Saavutetut tulokset on julkaistu eri osa-alojen foorumeilla
Opportunistic P2P Communications in Delay-Tolerant Rural Scenarios
Opportunistic networking represents a promising paradigm for support of communications, specifically in infrastructureless scenarios such as remote areas communications. In principle in opportunistic environments, we would like to make available all the applications thought for traditional wired and wireless networks like file-sharing and content distribution. In this paper, we present a delay-tolerant scenario for file sharing applications in rural areas, where an opportunistic approach is exploited. In order to support communications, we compare two peer-to-peer (P2P) schemes initially conceived for wireless networks and prove their applicability and usefulness to a DTN scenario, where replication of resources can be used to improve the lookup performance and the network can be occasionally connected by means of a data mule. Simulation results show the suitability of the schemes and allow to derive interesting design guidelines on the convenience and applicability of such approaches
On the Security and Feasibility of Safebook: A Distributed Privacy-Preserving Online Social Network
International audienceSafebook tackles the security and privacy problems of online social networks. It puts a special emphasis on the privacy of users with respect to the application provider and provides defenses against intruders or malicious users. In order to assure privacy in the face of potential violations by the provider, Safebook is designed in a decentralized architecture. It relies on the cooperation among the independent parties that represent the users of the online social network at the same time. Safebook addresses the problem of building secure and privacypreserving data storage and communication mechanisms in a peer-topeer system by leveraging trust relationships akin to social networks in real life. This paper resumes the contributions of [7, 9, 8], and extends the first performance and security evaluation of Safebook
Validation of H-P2PSIP, a scalable solution for interoperability among different overlay networks
This paper reports the results of experiments from an implementation of H-P2PSIP, a hierarchical overlay architecture based on the ongoing work in the IETF P2PSIP Working Group. This architecture allows the exchange of information among different independent overlay networks through the use of a two-layer architecture based on super-peers and hierarchical identifiers. The validation of this proposal is based on a Linux based real implementation where we have used four different scenarios with 1,000 peers in order to perform different experiments. We have obtained results for different parameters such as routing performance (number of hops), delay, routing state (number of overlay routing entries) and bandwidth consumption.This research
was supported in part by the European Commission Seventh
Framework Programme under grant agreement n 25774
(TREND Network of Excellence), Comunidad de Madrid grant
S-2009/TIC-1468 (MEDIANET project) and Spanish MICINN
grant TEC2011-29688-C02-02 (eeCONTENT project).Publicad
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