MBONE: Multicasting Tomorrow's Internet
The next field describes the session. It should ideally contain useful information, such as the targeted audience, whether the session is private or public, the main speaker, and so on.
Next, select what kind of data the session will be made of. You can select any combination of video, audio, and whiteboard. There are various protocols available for different types of data -- examples of available video formats are NV, VIC, and Cu-SeeMe.
Next, select the scope, perhaps the most delicate aspect of the creation of an MBONE event. The ìscopeî is also known as the TTL, or time to live, as explained in Chapter 4.
A scope too high sends your session to parts of the world that may not be interested in participating. Too low, and you unknowingly limit your audience. The scope should reflect your intended audience. If, for example, a session is created to allow the deans of California universities to share some ideas, selecting World as a scope would not be appropriate.
In the SD window, a World scope means that the TTL is set to 255, a Region scope is 128, and a Site scope is 64. These numbers will not always produce the desired effect for your situation. The scope depends heavily on the configuration of the various mrouters between you and the remote parties. You should inquire about the correct values from your network provider.
Finally, set the creation time and date and the duration of the event. Note that time zones affect the session. If you specify a time of 16:00, the creation time of the session is effectively 16:00 locally in all the time zones. If a remote party is in a time zone that is delayed by two hours relative to you, and you really want the session to start at 16:00, you should make the start time 14:00 so that the remote party in the other time zone can see it, too. See Figure 5-2.
Figure 5-2: SD session creation window.
When everything is set up, click the Create button. The session immediately appears in the main SD window, as shown in Figure 5-3. The session can be opened by clicking on the Open button. The MBONE applications corresponding to the data types you have selected at the creation step are now launched.
Figure 5-3: SD main window with a newly created event.
It takes a few minutes for the session advertisement to propagate to the rest of the MBONE. When users see the advertisement appear in their own SD window, they will be able to join the session by opening the advertisement. In your vat window, you will begin to see the advertisements appear as joined to the event.
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