1,721,050 research outputs found
Servizi di trasferimento a qualità garantita per applicazioni punto-punto e punto-multipunto in reti integrate
No full textTesi di Dottorato in Ingegneria dell'Informazione e della Comunicazion
IP Mobility Support in Private Access Networks: an Interworking Scenario between Mobile IP and NAPT
No full text
QoS Control by means of COPS to Support SIP based Applications
No full textThe COPS protocol has been designed to enable communication on the interface between the policy decision administrator and the policy enforcement devices in a policy-based networking environment, It can be recognized that on the some interface there is the need to transfer information related to the request of resource by QoS clients and for the allocation of resources by resource allocation servers (e.g., bandwidth broker) in a DiffServ network. Hence, it is sensible to add this resource allocation functionality in the COPS framework. In particular, there are at least two cases where it is sensible to use COPS. The first case is on the interface between an edge node and a resource control node for handling resource allocation in a network provider domain. The second case is on the interface between a customer (client of a QoS enabled network) and the network provider: here COPS can be used as a protocol to signal dynamic admission control requests. In this article we present the definition of a new COPS client type to support the above-mentioned functionality, then describe an application scenario where SIP-based IP telephony applications can use Diffserv-based QoS networks. Simple backward-compatible enhancements to SIP are needed to interact with COPS/Diffserv QoS. A testbed implementation of the proposed solutions is finally described
Reputation management algorithms for DHT-based peer-to-peer environment
No full textThis paper addresses the problem of integration of reputation management mechanisms into data lookup and routing processes to cope with some specific security problems in peer-to-peer (P2P) networks based on Distributed Hash Tables (DHT). The goal is to find a mode for ‘‘good” peers to cooperate in order to withstand malicious activity of single malevolent peers and their collusions as well. We start from consideration of individual instruments for reputation evaluation that every single peer should be provided with to autonomously define the level of its own trust towards others. We also propose a possible scenario of integration of some existing reputation management techniques and routing mechanisms in a P2P network based on the popular Kademlia algorithm. Then, we present an interaction algorithm that allows peers to obtain the global trust value for each single node through exchanging opinions in the form of local trust values independently calculated by every peer with other members of the community. Such collaboration between peers is indispensable to cope with malicious activity of inconsistent nature specific to DHT-based environment. To render the algorithm resilient to the presence of malicious participants we propose to apply solutions for Byzantine Agreement to exchange opinions among peers. We also provide mathematical evaluations concerning the complexity and computational costs of the proposed algorithm that evidence apparent improvements over the previous one
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