Towards Efficient Simulation of Large Scale P2P Networks
Tobias Hoßfeld, Andreas Binzenhöfer, Daniel Schlosser, Kolja Eger, Jens Oberender, Ivan Dedinski, Gerald Kunzmann
Research Report 371
Abstract
The algorithms and methods of the Peer-to-Peer (P2P) technology are often applied to networks and services with a demand for scalability. In contrast to traditional client/server architectures, an arbitrary large number of users, called peers, may participate in the network and use the service without losing any performance. In order to evaluate quantitatively and qualitatively such P2P services and their corresponding networks, different possibilities like analytical apporaches or simulative techniques can be used to improve the implementation of a simulation in general. This task is even more important for large scale P2P networks due to the number of peers, the state space of the P2P network, and the interactions and relationships between peers and states.
The goal of this work is to show how large scale P2P networks can be efficiently evaluated. Methods
are demonstrated how to avoid problems occuring in simulations of P2P services. Efficient data structures are required to deal with a large number of events, e.g. the application of a calendar queue for the simulation of a Kademlia-based P2P network, or the priority queue management to simulate eDonkey networks. In order to speed up computational time the simulation has to be implemented in an efficient way, asking for sophisticated programming. This can be achieved for example by using parallel simulation techniques which utilize the distribution and autonomy of the peers in the network.
Appropriate levels of abstraction and models for different application scenarios also improve the computational time for simulations of large scale P2P networks. An example is the simulation of throughput and round trip times in networks. We investigate a BitTorrent network on packet level, thereby, all details on the different layers are taken into account enabling us to study cross-layer interactions.
Next, we take a look on P2P network for signalling in voice/video over IP systems. In this context, the round trip time is crucial for the performance of the system. The packet layer and its most important characteristics are modeled in order to decrease memory consumption and computational power. Finally, an eDonkey network in a mobile telecommunication system is investigated. In that case we can neglect simulating packets and instead use a stream oriented approach for modeling the transmission of data.