All things related to multicast

[Jean-François Florence <>]

Zenon Mousmoulas a écrit :
> OK so let me see if I understand correctly:
>
> The cause of the problem was not that a video stream (corresponding to 
> the SAP announcement) was somehow "relayed" to the SAP group itself, 
> as we first thought (at least I did). On the contrary, the problem was 
> caused by miniSAPserver sending otherwise "normal" SAP announcements 
> at the amazing frequency of 33KHz, instead of the intended 0.03 Hz. 
> Right?
>
> If that is so, and that is what happened in each and every recent case 
> of a "SAP storm", then how do we explain the different bit/packet 
> rate, assuming everyone tried to set the suggested sap_delay=30?
>
> However Frank also notes this behavior was not consistent. So, do you 
> have any ideas what else could have triggered it, apart from this 
> setting? A specific video stream type perhaps?
>
> Would someone from Univ. Paris 13 want to share their experience? 
> Jean-Francois Florence perhaps?
Jean-Francois Florence is OK but only about ipv6 unicast and multicast , 
you can see the University on your dbeacon since ....and I can see some 
streams( audio and video ) from GRnet in v4 , all fine even in HD.
Can you tell me if you see annoucements ( in v4 and in v6 ) from UP13 ?
Notice that  s it s nt I who founded the bug, but one guy of my team : 
Michael Fortier.I said him to post on wg-multicast s list.
Best Regards
Florence

> Thanks for the info.
>
> Z.
>
> On 20 Ιουν 2008, at 3:13 ΜΜ, Frank Fulchiero wrote:
>
> > On Jun 20, 2008, at 7:04 AM, Niels den Otter wrote:
> >
> > > > I'm not sure if this is 'the bug', but I got an answer from the person
> > > that initiated the SAP stream yesterdam.
> > >
> > > He was setting up a miniSAP server (VLC) to announce a session via SDR.
> > > This appeared to work too good. Problem was in the announcement
> > > interval. The documentation said that the announcement interval should
> > > be provided in seconds, while the sourcecode would have a
> > > usleep(interval) so in microseconds.
> >
> > If that's true, that's probably how we caused the SAP storm in February.
> > But it's not always a consistent bug, as we ran it with a delay of 30 
> > for a whole day without problems:
> >
> > # sap.cfg - Configuration file of the mini SAP server
> >
> > # Global miniSAPserver options
> > [global]
> >
> > # Number of seconds between announces. 5 is default. Internet 
> > announces better use 30.
> > sap_delay=30
> >
> > # The network interface on which to stream.
> > interface=en0
> >
> > # Then you should have one "[program]" section per program announced
> >
> > # Note that only announces for MPEG2 TS streams are supported.
> > # Though announces of other types of streams may work for some clients,
> > # they will not be compliant to the announce spec. and are not at all
> > # guaranteed to work.
> >
> > # IPv4 example
> > [program]
> > # Name of the program (as it will show up in the VLC playlist)
> > name=ConnProgram1
> >
> > # Name of the streaming entity (organisation)
> > user=conncoll
> >
> > # DNS or IP of the machine on which you run the stream
> > machine=136.244.96.102
> >
> > # Website of the streaming entity (organisation)
> > site=http://www.conncoll.edu
> >
> > # Multicast IP address of the program
> > address=233.88.214.137
> >
> > # UDP Port
> > port=1234
> >
> > # The name of the playlistgroup your announce will be part of in the 
> > VLC playlist
> > playlist_group=ConncollPlaylist