3 What We Learned 2.2 Ip Multicast Routing First Ietf Internet Audiocast

and the rest of the SDSC crew for help getting the hardware and software set up at IETF; Steve Coya and Megan Davies for logistics; and Van Jacobson for work on vat and help in searching for the packet losses. Walt Prue set up a special route for the tunnel from San Diego to DART-net at ISI, and Milo Medin and Jeff Burgan set up a connection from DARTnet to FIX-West for a clear shot to Hawaii and Australia. We also thank the remote vat participants for their help as guinea pigs during testing. Simon Hackett in Ade-laide had to get up very early in the morning; Ian Wake-man and Jon Crowcroft in London, along with Anders Klemets and Steve Pink in Stockholm, had to stay up late at night. This points out one impediment to " distributing the IETF " that will be hard to fix: too many time zones! Appendix Software used in this experiment is available for testing by others who have Sun Sparcstations. A pre-release of the LBL audio tool vat is available by anonymous FTP from ftp.ee.lbl.gov in the file vat.tar.Z. Included are a binary suitable for use on any version of Sparcstation and a manual entry. The authors of vat say the source will be released " soon. " In addition, a beta release of both binary and source for the UMass audio tool NEVOT is available by anonymous FTP from gaia.cs.umass.edu in pub/nevot-0.91.tar.Z (the version number may change). You can test vat or NEVOT point-to-point between two hosts with a standard SunOS kernel, but to conference with multiple sites you will need a kernel with IP multi-cast support added. IP multicast invokes Ethernet multi-cast to reach hosts on the same subnet; to link multiple subnets you can set up tunnels, assuming sufficient bandwidth exists. You don't need kernel sources to add multicast support. Pick up the file vmtp-ip/ipmulti-sunos411.tar.Z by anonymous FTP from gregorio.stanford.edu. It contains the IP multicast code to be added to a SunOS 4.1.1 kernel. Once you build the kernel, you should use adb to permanently patch the kernel variable audio_79C30_bsize from the standard value of 1024 to be 180 decimal to match the audio packet size for minimum delay. Otherwise there will be bad breakup when sound from two sites gets mixed for playback. If you don't have a microphone for your Sparcstation, you can get one from Sun (part …