2002 - cesnet

scaling is considerably restricted; however, the number of participants takingpart in network meetings is limited by the very nature of such a meeting. Theoriginal simple reflector has been extended with a number of new characteristics.The motivation leading to the modifications can be described simply asfollows:• Sometimes, meetings need to be held behind closed doors, i.e., with datasent only to a defined number of participants who prove their identity.• It is useful to record important moments that will be replayed directly onthe server, not by individual participants.• Scaling, as a limiting characteristic of the mirror, has been solved in theform of interconnecting reflectors with tunnels.• It is possible to adjust to various bandwidth with the use of a special reflectormode, where individual data flows are combined into one flow. Interconnectionof this type reflector with a tunnel enables users’ communicationon lines with different throughput.• In addition, we added the possibility to log important activities on the reflectorand to monitor quality of data passing through.The extended reflector covers the user requirements and it has proved to bereliable and sufficient.Based on another modification of the reflector, we are able to synchronize moreflows with the use of accurate timestamps sent in the RTCP control protocol.The synchronized video flows are the basic element for the transmission of 3Dvideo signal, where separate flows are sent for each eye.6.3.2 H.323 Infrastructure in CESNET2We are continuing in the activities commenced during the previous period. Wehave set up a team comprised of CESNET’s employees and researchers fromthe projects titled Multimedia Transmissions in CESNET2, Voice Services in CES-NET2, and Quality of Services in High-speed Networks. The objective of this teamis to create a concept for further development of our H.323 infrastructure, tocoordinate procedures for the verification of this technology, support the use ofsoftware clients and create a secure and stable H.323 infrastructure.We have achieved some successes in the support of independent IP clients(Polycom ViewStation, PictureTel, GnomeMeeting). Important success of thisgroup lays in identification of problems associated with the security of access inthe existing H.323 infrastructure, and proposals for a solution of these problemsin coordination with projects of distributed AAA services (Shibboleth). Further-High-speed National Research Network and its New Applications 200283