Prodys PortaNet User Manual page 106

important thing to note is that when the transmitter is connected to the group, it
will start the streaming of audio data immediately.
connected, the audio will simply not be received.
connected to the multicast group they will receive the audio data that is being
streamed. Equally, if the receiver is connected to a multicast group where the
transmitter is not operating yet, the audio output is muted.
Multicast considerations:
Internet Protocol
technology that reduces traffic by simultaneously delivering a single
stream of information to thousands of corporate recipients and
homes.
Multicast is based on the concept of a group. An arbitrary group of
receivers expresses an interest in receiving a particular data
stream. This group does not have any physical or geographical
boundaries—the hosts can be located anywhere on the Internet.
Hosts that are interested in receiving data flowing to a particular
group must join the group using IGMP. All this is done
automatically by PortaNet when establishing a connection.
Multicast traffic is rejected when going through the Internet, since
most IP servers on the Internet do not currently support the
multicasting part of the protocol, except when using VPNs, because
VPNs encapsulates IP packets as unicast frames, so routers simply
see an ordinary packet.
All IP multicast group addresses will fall in the range of 224.0.0.0
to 239.255.255.255, but some of them are reserved, that's why the
range of addresses from 224.0.1.0 through 238.255.255.255 are
called globally scoped addresses.
There should only ever be one transmitter connected to a
MULTICAST group or else audio reception errors will occur.
For transmitting MULTICAST audio the Prodys proprietary protocol
"Prodys eXtended Real Time Protocol (PX-RTP) or SAP (according
to the new standard for IP compatibility) will be used.
The PortaNet transmitter cannot be in automatic encoding mode.
To guarantee a constant delay all the units must synchronise their
clocks.
adjusts its PLL (Phase-Lock Loop).
PortaNet User Manual
(IP) multicast
Each receiver will activate a clock-sync algorithm that
If there is no receiver
As soon as receivers are
is a bandwidth-conserving
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