Network

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Unterabschnitte

Bandwidth

Network

**Abbildung 2:** computer network without remote-stations
$\begin{figure} \par\epsfig{file=abb/system_net.eps,width=\textwidth}\par\end{figure}$

The needed physical computer-network for the whole system without the remote locations providing the streams are shown in figure 2.

Bandwidth

At a very early station of development we have to concentrate on Bandwidth issues, because this is a part which is a primary part of the system and are essential for the costs of the system.

Assume we need a lot of incoming Streams, an FTP-Server and out-streams which has to be guaranted by the band width.

The quality of the streams depend on their Bit-rate. We strongly encourage the use of MP3-streams, since they have better quality on the same bit-rate as real-audio. So we thought that a stream with 64kBit/sec would be a good solution. On the second hand streams with 64kBit are not able to be used on most analog modems, ISDN is needed. So there may be an alternative using 20kBit/sec. Anyway, the actual bit-rate could be different from stream to stream, dependent on their quality of input and the quality of international connection.

If we assume we have 12 remote streams in and one stream out plus overhead for FTP we get

count	type	bandwidth (kBit/sec)	total (kBit/s)
12	in streams	64	768
1	out stream MP3	64	64
1	out stream ra	32	32
1	FTP	128	128
?	interaction	?	?
1	overhead	128	128
TOTAL			?+ 1120

So there should be at least a 1MBit line to the system if there is a multicast server somewhere outside. So there is at least a load of the streams all the time.

So the amount of data transferred over the net is at least the streams all the time, which is 864 Kbit/s * 3600 (sec) * 24 = 74.649.600.000 Bits = 9 GBytes each day. In ten days this is 90 GByte.

We should make some reduction do make it realistic, but anyway, we have to face the maximum now, so that everything is working perfectly.

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HAss.DI Winfried Ritsch - ritsch@algo.mur.at