Blankom IRD-6100, Руководство пользователя

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BLANKOM IRD-6100 HD IRD User Manual
BLANKOM_IRD-6100_User_Manual_RR-V1.1-03-2018.doc - 42 -
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AD-HOC Block III (233.252.0.0-233.255.255.255 (233.252/14))

Unicast-Prefix-based IPv4 Multicast Addresses

Scoped Multicast Ranges

Relative Addresses used with Scoped Multicast Addresses
Multicast (as opposed to unicast) is used to send UDP packets from 1 source to multiple
destination servers. This is useful for example for streaming from a satellite/DVB-T receiver
to multiple receiving PCs for playback. Multicast can also be used on the output of an
encoder to feed multiple streaming servers. Multicast only works with UDP and is not
possible with TCP due to the 2 way nature of TCP, most commonly multicast is used with
RTP and MPEG2-TS.
A multicast IP address must be chosen according to IANA information, we recommend
using an address in the range
239.0.0.0 to 239.255.255.255 as this is reserved for private
use. Using multicast addresses in the 224.0.0.0 range may clash with existing services and
cause your stream to fail. For more details see
http://www.iana.org/assignments/multicast-addresses/multicast-addresses.xml
Choosing a UDP port number for multicast streams is also important. Even if you use a
different multicast IP for each of your streams, we strongly recommend using different
UDP port numbers as well. This is because a server and all software running on the server
receives ALL multicast traffic on an open port and extra processing is required to filter out
the required traffic. If the each stream arrives on a different port, the server can safely
ignore any traffic on ports that are not open. Port numbers MUST be chosen so that don't
clash with any existing services or ephemeral ranges. The ephemeral range for Windows
Vista, 7, 2008 is 49152 to 65535, for older Windows it is 1025 to 5000 and for Linux it is
32768 to 61000. For more information on Windows see
http://support.microsoft.com/kb/929851 Care should also be taken to avoid system ports
0 to 1024. See
http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numb
ers.xml
Generally one of the unassigned User Ports ( 1024-49151 ) should be used, you can
run the netstat -abn (as admin under windows) command to see which ports are currently
in use.
Registered port
A registered port is a network port (a sub-address defined within the Internet Protocol , in
the range 1024–49151) assigned by the Internet Assigned Numbers Authority (IANA) (or by
Internet Corporation for Assigned Names and Numbers (ICANN) before March 21, 2001,
[1]
or by USC/ISI before 1998) for use with a certain protocol or application.
Ports with numbers 0–1023 are called system or well-known ports ; ports with numbers
1024-49151 are called user or registered ports , and ports with numbers 49152-65535 are