Re: [Ccrtp-devel] Multicast and TTL - Again

[Tom Anwyll]

Not sure if anyone is following this thread. Not much
discussion on this. 

FWIW, here's where I'm at so far:

I guess no one has ever used ccRTP multicast across
subnets, becuase as it stands, it does not work. Using
an RTPSession object (as in the example code), the RTP
packets TTL field WILL ALWAYS be 1, despite doing a 
getDSO()->setTimeToLive(ttl)call. So, in essence,
ccRTP multicast is broken outside of the local
network.

If you want to do multicast across networks, *I think*
one must use a SymmetricRTPSession object. The code
snippet below does set the TTL correctly:

SymmetricRTPSession* s = new
SymmetricRTPSession(InetHostAddress("0.0.0.0"));
s->addDestination(InetHostAddress("235.1.1.1"),18800);
s->getDSO()->setMulticast(true);
s->getDSO()->setTimeToLive(32);

However, the RTCP packets TTL's are still set to 1, so
I suppose that RTCP information will never travel
beyond the local network. I assume RTP will work
without RTCP.

If anybody has some advice or good ideas, please feel
free to chime in.

Thanks,
Tom


--- Tom Anwyll <address@hidden> wrote:

> Hello RTP Gurus,
> 
> I am having trouble setting the TTL on a multicast
> socket. Despite my best efforts, ethereal still
> shows the TTL field of my packets set to 1.
> 
> FYI, I'm using ccRTP 1.3.6 and commoncpp 1.3.22
> 
> code snippet 
> 
> RTPSession* s = new RTPSession(
> INetHostAddress("0.0.0.0"));
> s->addDestination(
> InetHostAddress("235.1.1.1"),18800);
> s->getDSO()->setMulticast(true); // <-- This was
> needed to avoid crash on next line -- not sure if
> this is right
> s->getDSO()->setTimeToLive(32);
> 
> Any ideas about what I am doing wrong or how to set
> multicast TTL's > 1?
> 
> TIA,
> Tom
>  
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