[AG-TECH] VPCscreen behaviour

[Philippe d'Anfray]

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



 
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