Οικονομικό Πανεπιστήμιο Αθηνών, Τμήμα Πληροφορικής
The aim of this project is the study of the KIXEM application[3] [4] which provides information about the quality of network services. The study deals with the implementation of KIXEM application in wireless community networks and more specifically in Athens Wireless Metropolitan Network (AWMN)[5][6]. In addition, a graphical user interface has been developed in order to show graphically the topology of the routers, which are monitored by KIXEM application, leading to useful conclusions about the traffic flows that are served by them. The documentation consists of three chapters. The first chapter defines the task ahead very clearly and the general conceptual foundation that is required for a good comprehension of the whole documentation. The second chapter refers to Athens Wireless Metropolitan Network and its provided services. Moreover, it describes the way KIXEM can be incorporated in the routers of Athens Wireless Metropolitan Network. The third chapter describes the graphical user interface. Specifically, it describes the functional and non-functional requirements, as well as, the stages of the development. Also, it refers to the difficulties that were appeared while developing and the way of solving these problems. Finally, the graphical user interface manual is given in Appendix A, while the source code in Appendix B.KIXEM is based on passive traffic monitoring of the network. Passive traffic monitoring is important because the measurements do not influence the regular operation of the network. Precise, in other words, they do not increase the network traffic. Besides, the data that are collected reflected to the ordinary functionality of the network. The architecture of KIXEM is quite simple. It is constituted by a number of agents and a server. The agents are incorporated in the routers, which are monitored, and the server is connected with a database. When the agents are activated by a server command, they “capture” the packages that go across the routers and store specific information for each one. When their capturing time expires, the data are compressed and sent to the server. The server performs a series of operations on data in order to calculate the values of the specific metrics. The results of the calculations are stored in the database. Athens Wireless Metropolitan Network is a wireless community that aims at the development and the promotion of wireless broadband network, not only in the region of Athens, but also in the wider region of Greece. There are not specific standards and rules. As a consequence of this, there is heterogeneity and also many technical and operational problems. Athens Wireless Metropolitan Network provides a variety of services, such as peer-to-peer services, internet proxy servers, game servers, voice over ip servers, etc. So, this network constitutes a microcosm of World Wide Web. It is worth mentioned, that the registration of members and the use of the provided services do not involve any expenses. A person who wants to be a member of Athens Wireless Metropolitan network has only to buy the appropriate network equipment. With reference to the technological characteristics, Athens Wireless Metropolitan Network uses the IEEE 802.11a protocol to connect the nodes of the backbone network. The nodes usually use an access point so that the users (specifically the clients) can have access to the network. The operation of access points is based on IEEE 802.11b protocol. Finally, routing uses BGP. This protocol is not appropriate as it examines only the distance between the nodes. There are more appropriate protocols that examine the consequences of the network load (OLSR Confederations). KIXEM incorporation in the routers of Athens Wireless Metropolitan Network would be useful, as it could improve the quality of the services. In addition to this, the results of the calculations could contribute to the appropriate routers configuration and also to the better performance of the network. However, the extensive use of the Mikrotik operation system[7] is a negative factor in the implementation of KIXEM.As a consequence, a network simulator (NCTUns [9][10]) is used in order to create a part of the network topology and examine the operation of KIXEM. As the network simulator does not support graphical applications, the graphical environment of KIXEM server has not been executed. For this reason, a number of flows are added in the simulated network. The packages of these flows are “captured”, using the tcpdump[12] tool and a parser that has been developed for this purpose. The extracted information is the input server accepts. In other words, tcp dump, in combination with the parser, behaves like an agent. It has already mentioned that KIXEM consists of a number of agents and a server. The agents “capture” the packages and retrieval the essential information, while the server, after data processing, stores the information in a database. In the past, there was not any application that would represent the data in a way which could help users in drawing some conclusions. For this reason , a graphical user interface has been developed. This interface represents graphically the topology and also the information that are stored in the database. Initially, the user selects the routers, interfaces or edges/hops. Then the values of the elements of the specific flows are calculated. In case of selecting edges the values can be calculated either in the form of sum or in the form of average. Finally, the user examines the results and decides on the appropriate routers configuration.
Quality of network
KIXEM
Ποιότητα υπηρεσιών δικτύου