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1 Advances in Electronics and Telecommunications

1 2011

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Agent based VoIP Application with Reputation Mechanisms

100%

Oryńczak G. , Kotulski Z.

tom Vol. 2, no. 3

88--92

In this paper we introduce our new VoIP model the aim of which is to meet the challenges of modern telephony. We present project concepts, details of implementation and our testing environment which was designed for testing many aspects of VoIP based systems. Our system combines mechanisms for ensuring best possible connection quality (QoS), load balance of servers in infrastructure, providing security mechanisms and giving control over the packet routing decisions. The system is based on Peer-to-Peer (P2P) model and data between users are routed over an overlay network, consisting of all participating peers as network nodes. In the logging process, each user is assigned to a specific node (based on his/her geographic location and nodes load). Every node also has a built-in mechanism allowing to mediate between the user and the main server (e.g. in logging process). Besides that, because nodes are participating in data transmission, we have control over the data flow route. It is possible to specify the desired route, so, regardless of the external routing protocol, we can avoid paths that are susceptible to eavesdropping. Another feature of presented system is usage of agents. Each agent acts with a single node. Its main task is to constantly control the quality of transmission. It analyzes such parameters like link bandwidth use, number of lost packets, time interval between each packets etc. The information collected by the agents from all nodes allows to built a dynamic routing table. Every node uses Dijkstra’s algorithm to find the best at the moment route to all other nodes. The routes are constantly modified as a consequence of changes found by agents or updates sent by other nodes. To ensure greater security and high reliability of the system, we have provided a reputation mechanism. It is used during updating of the information about possible routes and their quality, given by other nodes. Owing to this solution nodes and routes which are more reliable get higher priority.