Research papers

This paper presents an overview of the current web client – web proxy – web server mechanism and takes a deep look into one of its main disadvantages: the replication, in the proxy’s cache, of web objects having different URL but the same content. This problem is known as the Duplicate Transfer problem and is mainly caused by the current mode of indexing web objects based on their URL, which is used as a primary key in the cache repository. We present in this paper a statistical analysis based on real traffic measurements, which shows that more than 10% of a proxy’s cache consists of replicated objects, grabbed from the Internet in a useless manner and stored redundantly at least twice. These results urge the development of a scalable real-life solution to the duplicate transfer problem: some solutions have been previously proposed, but never deployed on a large scale in Internet. Continue Reading →

This paper presents a new approach for shared bottlenecks detection from a receiver’s perspective. This approach uses flow clustering at the receiver, based on passive observations of inter-packet arrival time intervals. We also suggest a new cost function useful in the flows clusterization process into macroflows. The proposed method can be used in the discovery of path patterns or for extending the macroflow granularity in an improved Congestion Manager. Continue Reading →

published in Proceedings of the Knowledge Engineering Principles and Techniques Conference, KEPT 2007, Cluj-Napoca, pp. 227-235, June 2007. Cite as

Full paper Some Formal Approaches for Dynamic Life Session Management Authors Florian Boian, Darius Bufnea, Alexandru Vancea, Adrian Sterca,… Continue Reading →

Some of the newest approaches in Internet congestion control management suggest collaboration between sets of streams that should share network resources and learn from each other about the state of the network. A set of such collaborating streams is called a macroflow. In classical congestion control approach, a stream learns information about the network state by itself. It makes use of the acquired knowledge to adapt its transmission rates to the current network conditions. Stream collaboration, in exchange, permits dissemination of network state knowledge: the streams in a macroflow maintain common information about the network state. Every stream in that macroflow uses this shared knowledge and contributes to its maintenance. This dissemination of network knowledge conducts to a better, faster and more flexible adaptation of flow behavior in presence of network congestion. The remaining problem is how to identify the streams forming such a logical entity (a macroflow). Currently a macroflow is organized on host pair basis. We propose in this paper a new method for grouping streams into macroflows if they behave similarly. A flow behavior is described by a set of state variables, such as the congestion window size, the round trip time or retransmission time out. This extended macroflow granularity can be used in an improved Congestion Manager. Continue Reading →