TRANSMISSION OF A PRESENTATION IN A TREE NETWORK TOPOLOGY

Knowledge transfer to students or in general to a group of people is realized in many ways. The standard form is teacher's delivering lectures to the audience in the same room. This is a commonly used and effective style of presentation. If the students are interested in the topic, they can be directly involved in the presentation. If a student cannot take part in the presentation, it is necessary to provide consultations or let the student study the topic themselves. Another modern method of lecturing is a remote presentation so that students can follow the lecturer in another room or even at home. With the help of current technologies listeners can use a computer, cell-phone or tablet-pc and simply follow the teacher on the screen of their device in real time. In the best way the record of lecturer's presentation is stored in a web repository so that the students can follow the talk offline as well. In this paper we deal with the first option that is following the lecturer online. It is evident that online presentation is associated with quite a lot of problems concerning the form and mode of transmission of video and audio. The biggest weakness of such systems is the limited number of concurrent participants. This limitation is usually due to the server side, because the server fails to serve a larger number of clients. If the data transfer is realized by just one server, we are limited not only by the performance of the server, but also its transmission bandwidth. In order to make it possible that a larger number of students would share a video and audio, we must be able to spread the load among several nodes (servers) that are involved in the transfer. These servers are then connected in a tree network topology. To this end an algorithm and protocol have been designed such that data transmission is realized in the above described way. In this paper we describe such a protocol and introduce the strategy of data transmission in a tree network topology. We will also deal with practical results that were obtained during full operation of the system.