You probably recognize that for IPv4 SSM your multicast must use a destination
address like 232.x.y.z
Per RFC4607
The benefits of source-specific multicast include:
Elimination of cross-delivery of traffic when two sources
simultaneously use the same source-specific destination address.
The simultaneous use of an SSM destination address by multiple
sources and different applications is explicitly supported.
Avoidance of the need for inter-host coordination when choosing
source-specific addresses, as a consequence of the above.
Avoidance of many of the router protocols and algorithms that are
needed to provide the ASM service model.
Also:
SSM is particularly well-suited to dissemination-style applications
with one or more senders whose identities are known before the
application begins. For instance, a data dissemination application
that desires to provide a secondary data source in case the primary
source fails over might implement this by using one channel for each
source and advertising both of them to receivers.
Regards,
Andrew
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of David Henry
Sent: Wednesday, October 24, 2012 1:31 PM
To: [email protected]
Subject: [Libav-user] IGMPv3 source-specific multicast: what is the purpose of
multiple sources?
While using the relatively new feature of source-specific multicast (patched
with
http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=75d339e044f9b87dd9aa4bdaee73b1a8323d4a15)
I tried giving 2 sources, instead of a single source. e.g.
udp://[email protected]:3100?sources=172.31.1.21,172.31.2.21
I assumed (incorrectly) that the linux kernel would fail-over to the 2nd source
if there was an interruption or some other error with the first source.
Instead, I'm just getting packets from both sources simultaneously, which is
not useful for me.
So the question is:
1) for streaming video, why would one want this sort of behavior? (packets
delivered simultaneously from >1 source)
2) is there any way to dynamically implement fail-over at the receiver with
ffmpeg & source-specific multicast?
Thanks, David
_______________________________________________
Libav-user mailing list
[email protected]
http://ffmpeg.org/mailman/listinfo/libav-user
_______________________________________________
Libav-user mailing list
[email protected]
http://ffmpeg.org/mailman/listinfo/libav-user
