Hi, Yes, the ttl looks like the culprit. Are you sure that -t is the correct way to set the ttl in VPCScreen?
Andrew :) --------------------------------------------------------- Andrew G D Rowley Senior Development Officer Research Computing Services The University of Manchester Devonshire House, Oxford Road Manchester, M13 9PL t : +44 (0) 161 275 0685 e : andrew.row...@manchester.ac.uk w : www.manchester.ac.uk/researchcomputing --------------------------------------------------------- > -----Original Message----- > From: ag-tech-boun...@lists.mcs.anl.gov [mailto:ag-tech- > boun...@lists.mcs.anl.gov] On Behalf Of Philippe d'Anfray > Sent: 30 March 2010 16:00 > To: ag-t...@mcs.anl.gov > Subject: Re: [AG-TECH] VPCscreen behaviour > > Andrew Rowley a écrit : > > > > > > 1) Can you run a wireshark > > > > 2) The network people are unlikely > > > > 3) Can I also check that vic (I assume it is vic you are using to > transmit video) and VPCScreen are running on the same multicast address > and port? > > > > 4) A summary of your problem is that multicast appears to be working (as > attested to by the working video transmission and reception) but VPCScreen > specifically doesn't seem to be getting out of the machine. Is this > correct? > > > > Bonjour, > > 4) Yes exactly !!! > > 1) Hum! it seems that "in fine" TTL is only set to 16 ? (see capture) > and according to this Tutorial, > http://ntrg.cs.tcd.ie/undergrad/4ba2/multicast/antony/ it is normal > that we are restricted to "our site" > > > > > > As the values of the TTL field increase, routers will expand the > > number of hops they will forward a multicast packet. To provide > > meaningful scope control, multicast routers enforce the following > > "thresholds" on forwarding based on the TTL field: > > > > *0* > > restricted to the same host > > *1* > > restricted to the same subnet > > *32* > > restricted to the same site > > *64* > > restricted to the same region > > *128* > > restricted to the same continent > > *255* > > unrestricted > > > > This might be the solution, we just have to find how 127 becomes 16.... ? > > Cordialement > > Philippe > > > > > 2) Yes of course. We use UBUNTU boxes that we installed ourselves so we > know what's inside I just checked for a "strange rule" in our site > firewall... > > 3) If I start VPCscreen and a Video producer service I have the same > addres/port (and TTL) > > /usr/bin/VPCScreenCapture ...... -t 127 224.2.141.24/61520 > vic ...........-t 127 224.2.141.24/61520 > > > >
