Using multicast in the global communications infrastructure for group211 communication

摘要

International Monitoring System (IMS) stations and the International Data Centre211u001e(IDC) of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty 211u001eOrganization generate data and products that must be transmitted to one or more 211u001ereceivers. The application protocols used to transmit the IMS data and IDC 211u001eproducts will be CD-x and IMS-x and the World Wide Web (WWW). These protocols use 211u001eexisting Internet applications and Internet protocols to send their data. The 211u001eprimary Internet applications in use are electronic mail (e-mail) and the file 211u001etransfer protocol (ftp). The primary Internet communication protocol in use is 211u001ethe Transmission Control Protocol (TCP), which provides reliable delivery to the 211u001ereceiver. These Internet applications and protocol provide unicast (point-to-211u001epoint) communication. A message sent using unicast has a single recipient; any 211u001emessage intended for more than one recipient must be sent to each recipient 211u001eindividually. In the current design, the IDC and the National Data Centres 211u001e(NDC's) provide data forwarding to the appropriate receivers. The overhead 211u001eassociated with using unicast to transmit messages to multiple receivers either 211u001edirectly or through a forwarder increases linearly with the number of receivers. 211u001eIn addition, using a forwarding site introduces possible delays and possible 211u001epoints of failure in the path to the receivers. Reliable multicast provides 211u001ecommunication services similar to TCP but for a group of receivers. The reliable 211u001emulticast protocol provides group membership services and message delivery 211u001eordering. If an IMS station were to send its data using reliable multicast 211u001einstead of unicast, only sites that are members of the multicast group would 211u001ereceive the data at approximately the same time. This might provide an efficient 211u001emeans of disseminating station data or IDC data products to all receivers and 211u001eeliminate or greatly reduce the need for data forwarding. Several commercial and 211u001eresearch reliable multicast protocols exist for the Internet. Each of these 211u001eprotocols is designed to serve a specific community of users and applications. 211u001eThe author has undertaken a study to determine if reliable multicasting is 211u001eappropriate for use in the Global Communication Infrastructure (GCI).